Page 1
MODEL G0791
COMBINATION GUNSMITHING
LATHE/MILL
OWNER'S MANUAL
(For models manufactured since 9/15)
COPYRIGHT © MAY, 2015 BY GRIZZLY INDUSTRIAL, INC., REVISED MAY, 2017 (BL)
WARNING: NO PORTION OF THIS MANUAL MAY BE REPRODUCED IN ANY SHAPE
OR FORM WITHOUT THE WRITTEN APPROVAL OF GRIZZLY INDUSTRIAL, INC.
#WKBB17270 PRINTED IN CHINA
V2 .10 .17
Page 2
Page 3
Table of Contents
INTRODUCTION ............................................... 3
Contact Info.................................................... 3
Manual Accuracy ........................................... 3
Identification ................................................... 4
Controls & Components ................................. 5
Machine Data Sheet ...................................... 8
SECTION 1: SAFETY ..................................... 11
Safety Instructions for Machinery ................ 11
Additional Safety for Metal Lathes ............... 13
Additional Safety for Mills ............................ 14
Additional Lathe Chuck Safety..................... 15
SECTION 2: POWER SUPPLY ...................... 16
SECTION 3: SETUP ....................................... 18
Preparation .................................................. 18
Unpacking .................................................... 18
Needed for Setup ......................................... 18
Inventory ...................................................... 19
Cleanup ........................................................ 20
Site Considerations ...................................... 21
Assembly ..................................................... 22
Anchoring to Floor ....................................... 25
Leveling ........................................................ 25
Lubricating Lathe ......................................... 26
Power Connection........................................ 26
Test Run ...................................................... 28
Spindle Break-In .......................................... 30
Recommended Adjustments ........................ 31
SECTION 4: LATHE OPERATIONS .............. 32
Operation Overview ..................................... 32
Chuck & Faceplate Mounting....................... 33
Chuck Safety & Support Devices ................ 33
Chuck Installation......................................... 34
Chuck Removal............................................ 35
Scroll Chuck Clamping ................................ 36
Chuck Jaw Reversal .................................... 36
4-Jaw Chuck ................................................ 37
Faceplate ..................................................... 38
Tailstock ....................................................... 39
Centers ........................................................ 43
Joining Drill Chuck & Arbor .......................... 45
Steady Rest ................................................. 46
Follow Rest .................................................. 47
Carriage & Slide Locks ................................ 47
Compound Rest ........................................... 47
Tool Post ...................................................... 48
Spider ........................................................... 50
Manual Feed ................................................ 50
Spindle Speed.............................................. 51
Understanding Gear Charts ......................... 52
Power Feed.................................................. 55
End Gears .................................................... 58
Threading ..................................................... 61
SECTION 5: MILL OPERATIONS .................. 64
Operation Overview ..................................... 64
Removing Compound Rest .......................... 65
Downfeed Controls ...................................... 66
Headstock Movement .................................. 67
Table Travel ................................................. 68
Installing/Removing Tooling ......................... 69
Spindle Speed.............................................. 71
Page 4
SECTION 6: ACCESSORIES ......................... 72
SECTION 7: MAINTENANCE ......................... 76
Schedule ...................................................... 76
Cleaning/Protecting ...................................... 76
Lubrication ................................................... 77
Machine Storage .......................................... 82
SECTION 8: SERVICE ................................... 83
Troubleshooting ........................................... 83
Adjusting Backlash....................................... 86
Adjusting Gib................................................ 87
Adjusting Half Nut ........................................ 89
Tensioning/Replacing V-Belt........................ 89
Installing/Removing Gap Insert .................... 90
Adjusting Spindle Bearing Preload .............. 91
SECTION 9: WIRING ...................................... 94
Wiring Safety Instructions ............................ 94
Wiring Overview ........................................... 95
Electrical Cabinet Wiring Diagram ............... 96
Lathe Motor Wiring Diagram ........................ 98
Mill Motor & Work Lamp Wiring Diagram .... 99
Control Panel Wiring Diagrams ................. 100
SECTION 10: PARTS ................................... 101
Accessories ................................................ 101
Headstock Gearing .................................... 103
Headstock Controls.................................... 105
Quick-Change Gearbox ............................. 107
Apron ......................................................... 109
Saddle & Cross Slide ................................. 111
Compound Rest & Tool Holder .................. 113
Tailstock ..................................................... 114
Lathe Motor, Bed, & Stand ........................ 115
Feed Rod ................................................... 117
Machine Labels & Cosmetics .................... 118
Electrical Components ............................... 119
Steady Rest ............................................... 120
Follow Rest ................................................ 120
Mill Headstock............................................ 121
Column & Fine Downfeed .......................... 124
SECTION 11: APPENDIX ............................. 125
Feed Chart ................................................. 125
Thread Dial Chart ...................................... 125
Metric Threading Chart .............................. 125
Inch Threading Chart ................................. 125
WARRANTY & RETURNS ........................... 129
Page 5
INTRODUCTION
Contact Info Manual Accuracy
Model G0791 (Mfd. Since 9/15)
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Page 6
Identification
D
C
B
A
U
E GF H
I
J
K
L
M
N
O
P
T
A. Quick-Change Gearbox Controls (see Page 5
for details)
B. Headstock Controls (see Page 5 for details)
C. End Gear and Belt Cover
D. 3-Jaw Chuck
E. Halogen Work Light
F. Mill Spindle Speed Shift Levers
G. Mill Vertical Travel Handwheel
H. Fine Downfeed Handwheel
I. Coarse Downfeed Handwheel
J. Compound Rest Handwheel
S
K. Tailstock (see Page 6 for details)
L. Back Splash
M. Longitudinal Leadscrew
N. Feed Rod
O. Control Rod
P. Chip Tray
Q. Storage Cabinet
R. Stand Mounting Points (2 of 4)
S. Carriage (see Page 6 for details)
T. Storage Cabinet
U. Quick-Change Tool Post
Q
R
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Model G0791 (Mfd. Since 9/15)
Page 7
Controls &
A. Spindle Speed Levers: Used to select one
of the nine spindle speeds.
Components
Refer to Figures 1–5 and the following descrip-
tions to become familiar with the basic controls of
this machine.
Many of the controls will be explained in greater
detail later in this manual.
Lathe Headstock & Quick-Change
Gearbox
A
B
G
C
D
E
F
H
B. Feed Direction Lever: Controls rotation
direction of leadscrew and feed rod.
C. Metric Threading Chart: Displays the nec-
essary configuration of gearbox levers and
end gears for metric threading options.
D. Emergency Stop/RESET Button: Stops all
machine functions. Twist clockwise to reset.
E. Spindle Speed Chart: Shows how to arrange
spindle speed levers for each of the nine
spindle speeds.
F. POWER Start Button: Enables power to
lathe/mill spindle motors after the emergency
stop button is reset.
G. INCHING (Jog) Button: Rotates spindle as
long as it is pressed.
H. POWER Lamp: Illuminates when lathe con-
trols are receiving power (Emergency Stop/
RESET button must be reset).
I. Mill FWD/REV Switch: Selects between
forward and reverse mill spindle rotation.
Setting the switch to the "Mill" position turns
the mill OFF.
I
J
L
Figure 1. Headstock and quick-change gearbox
controls.
Model G0791 (Mfd. Since 9/15)
K
J. Headstock Feed Selection Lever: Selects
leadscrew for threading operations or feed
rod for power feed operations.
K. Quick-Change Gearbox Levers: Control the
leadscrew and feed rod rotation speeds for
threading and power feed operations.
L. Inch Threading Chart: Displays the neces-
sary configuration of gearbox levers and end
gears for inch threading options.
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Page 8
Carriage
Tailstock
M
U
T
S
R
Figure 2. Carriage controls.
M. Quick-Change Tool Post: Allows the opera-
tor to quickly load and unload tools.
N. Compound Rest Handwheel: Moves tool
toward or away from workpiece at the preset
angle of compound rest.
N
O
P
Q
V
Y. Quill Handwheel: Moves quill toward or
Z.
W
Figure 3. Tailstock controls.
away from spindle.
1
⁄2" Square-Drive Lock-Down: Used with a
torque wrench for precise alignment of centers.
X
AA
Y
Z
O. Carriage Lock Cap Screw: Secures car-
riage in place for greater rigidity.
P . Thread Dial: Indicates when to engage half
nut during inch threading operations.
Q. Spindle Lever: Starts, stops, and reverses
direction of spindle rotation.
R . Half Nut Lever: Engages/disengages half
nut for threading operations.
S. Apron Feed Selection Lever: Selects car-
riage or cross slide for power feed.
T. Carriage Handwheel: Moves carriage along
bed.
U. Cross Slide Handwheel: Moves tooling
toward or away from the workpiece.
V. Quill: Holds centers and tooling.
W. Quill Lock Lever: Secures quill in position.
AA. Tailstock Offset Screw (1 of 2): Adjusts
tailstock offset left or right from spindle
centerline.
End Gears
End
Gears
Figure 4. End gears.
Configuring the end gears (shown in Figure 139)
controls the speed of the leadscrew for threading
or the feed rod for power feed operations.
X. Tailstock Lock Lever: Secures tailstock in
position along bedway.
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Model G0791 (Mfd. Since 9/15)
Page 9
Milling Headstock
AK
AJ
Figure 5. Milling headstock controls.
AB
AE. Depth Scale Lock Knob: Locks the depth
scale in position.
AC
AF. Coarse Downfeed Handwheel: Moves spin-
AD
AE
AF
AG
AHAI
dle down quickly when rotated and automatic
spring return brings spindle back up to top
when you release downward pressure on
handles. Typically used for drilling holes or
checking spindle positioning during setups.
AG. Downfeed Selector Knob: Push in to
engage fine downfeed; pull out to engage
coarse downfeed.
AH. Depth Pointer and Scale: Indicates vertical
position of the quill.
AB. Mill Spindle Speed Shift Levers: Select
between 250, 530, 1100, and 2300 RPM.
AC. Vertical Travel Handwheel: Raises and low-
ers headstock for Z-axis control over spindle
positioning during setups.
AD. Z-Axis Lock Bolt: Locks vertical position of
mill headstock when tightened.
AI. Fine Downfeed Handwheel: Provides fine
control over vertical spindle travel to provide
Z-axis control when milling.
AJ. Mill Spindle Speed Chart: Indicates shift
lever positions for various spindle speeds.
AK. Quill Lock Bolt: Locks vertical position of
quill (or Z-axis) when tightened. Typically
used in conjunction with spindle downfeed
controls when milling.
Model G0791 (Mfd. Since 9/15)
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Page 10
Centrifugal Switch/Contacts Type.......................................................................................................... Internal
Machine Data Sheet
MACHINE DATA
SHEET
Customer Service #: (570) 546-9663 · To Order Call: (800) 523-4777 · Fax #: (800) 438-5901
MODEL G0791 12" X 36" COMBINATION GUNSMITHING
LATHE/MILL
Product Dimensions:
Weight............................................................................................................................................................ 1345 lbs.
Width (side-to-side) x Depth (front-to-back) x Height..................................................................... 66 x 27-1/2 x 75 in.
Footprint (Length x Width)............................................................................................................... 57-1/2 x 14-1/2 in.
Shipping Dimensions:
Carton #1
Type................................................................................................................................................ Wood Crate
Content................................................................................................................................................. Machine
Weight.................................................................................................................................................. 1367 lbs.
Length x Width x Height............................................................................................................. 67 x 29 x 52 in.
Must Ship Upright......................................................................................................................................... Yes
Carton #2
Type........................................................................................................................................... Cardboard Box
Content............................................................................................................................................... Left Stand
Weight.................................................................................................................................................... 106 lbs.
Length x Width x Height............................................................................................................. 30 x 14 x 15 in.
Must Ship Upright.......................................................................................................................................... No
Carton #3
Type........................................................................................................................................... Cardboard Box
Content............................................................................................................................................ Right Stand
Weight...................................................................................................................................................... 93 lbs.
Length x Width x Height............................................................................................................. 31 x 12 x 15 in.
Must Ship Upright.......................................................................................................................................... No
Electrical:
Power Requirement........................................................................................................... 220V, Single-Phase, 60 Hz
Full-Load Current Rating....................................................................................................................................... 8.5A
Minimum Circuit Size.............................................................................................................................................. 15A
Connection Type....................................................................................................................................... Cord & Plug
Recommended Power Cord............................................................................... "S"-Type, 3-Wire, 14 AWG, 300 VAC
Plug Included........................................................................................................................................................... No
Recommended Plug Type..................................................................................................................................... 6-15
Switch Type............................................................................................ Control Panel w/Magnetic Switch Protection
Motors:
Mill Spindle
Horsepower............................................................................................................................................. 3/4 HP
Phase............................................................................................................................................ Single-Phase
Amps........................................................................................................................................................... 4.5A
Speed................................................................................................................................................ 1720 RPM
Type................................................................................................................. TEFC Capacitor-Start Induction
Power Transfer ................................................................................................................................. Gear Drive
Bearings..................................................................................................... Shielded & Permanently Lubricated
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Model G0791 (Mfd. Since 9/15)
Page 11
Lathe Spindle
Horsepower................................................................................................................................................ 2 HP
Phase............................................................................................................................................ Single-Phase
Amps........................................................................................................................................................... 8.5A
Speed................................................................................................................................................ 1725 RPM
Type................................................................................................................. TEFC Capacitor-Start Induction
Power Transfer ...................................................................................................................... Twin V-Belt Drive
Bearings..................................................................................................... Shielded & Permanently Lubricated
Centrifugal Switch/Contacts Type.......................................................................................................... Internal
Main Specifications:
Lathe Info
Swing Over Bed......................................................................................................................................... 12 in.
Distance Between Centers........................................................................................................................ 36 in.
Swing Over Cross Slide............................................................................................................................... 7 in.
Swing Over Saddle............................................................................................................................ 11-5/16 in.
Maximum Tool Bit Size............................................................................................................................. 5/8 in.
Compound Travel.................................................................................................................................. 3-1/4 in.
Carriage Travel.................................................................................................................................... 30-1/2 in.
Cross Slide Travel................................................................................................................................. 6-1/4 in.
Spindle Bore........................................................................................................................ 1.57 in. (39.87mm)
Spindle Taper............................................................................................................................................ MT#5
Number Of Spindle Speeds.............................................................................................................................. 9
Spindle Speeds......................................................................................................................... 70 – 1400 RPM
Spindle Type................................................................................................................................ D1-5 Camlock
Spindle Bearings................................................................................................ High-Precision Tapered Roller
Spindle Length........................................................................................................................................... 17 in.
Spindle Length with 3-Jaw Chuck....................................................................................................... 21-3/4 in.
Spindle Length with 4-Jaw Chuck....................................................................................................... 21-1/4 in.
Spindle Length with Faceplate............................................................................................................ 18-1/2 in.
Tailstock Quill Travel................................................................................................................................... 4 in.
Tailstock Taper.......................................................................................................................................... MT#3
Tailstock Barrel Diameter..................................................................................................................... 1.563 in.
Number of Longitudinal Feeds....................................................................................................................... 40
Range of Longitudinal Feeds........................................................................................ 0.0011 – 0.0310 in./rev.
Number of Cross Feeds................................................................................................................................. 40
Range of Cross Feeds.................................................................................................. 0.0004 – 0.0105 in./rev.
Number of Inch Threads................................................................................................................................. 40
Range of Inch Threads.................................................................................................................... 4 – 112 TPI
Number of Metric Threads.............................................................................................................................. 29
Range of Metric Threads............................................................................................................... 0.2 – 4.5 mm
Model G0791 (Mfd. Since 9/15)
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Page 12
Mill Info
Mill Taper...................................................................................................................................................... R-8
Mill Spindle Travel................................................................................................................................. 2-1/4 in.
Mill Swing................................................................................................................................................... 15 in.
Distance Spindle To Work Table............................................................................................................... 12 in.
Distance Spindle To Bed..................................................................................................................... 14-1/4 in.
Distance Spindle To Center Line........................................................................................................... 8-3/8 in.
Mill Head Vertical Travel...................................................................................................................... 11-1/2 in.
Mill Head Tilt (Left/Right)........................................................................................................................ 90 deg.
Maximum Tool Bit Size............................................................................................................................. 5/8 in.
Drilling Capacity For Steel........................................................................................................................ 5/8 in.
Drilling Capacity For Cast Iron.................................................................................................................. 3/4 in.
Table Size Length.................................................................................................................................. 9-3/4 in.
Table Size Width................................................................................................................................... 5-7/8 in.
Table Size Thickness.......................................................................................................................... 1-5/16 in.
Number of T-Slots............................................................................................................................................ 2
T-Slot Size................................................................................................................................................ 3/8 in.
T-Slot Centers..................................................................................................................................... 2-7/16 in.
Drawbar Diameter................................................................................................................................... 7/16 in.
Drawbar TPI............................................................................................................................................. 20 TPI
Drawbar Length..................................................................................................................................... 9-1/4 in.
Number of Mill Drill Speeds.............................................................................................................................. 4
Mill Speed Range.................................................................................................................... 250 – 2300 RPM
Construction
Bed........................................................................................ Induction-Hardened, Precision-Ground Cast Iron
Headstock............................................................................................................................................ Cast Iron
Body..................................................................................................................................................... Cast Iron
End Gears...................................................................................................................... Flame-Hardened Steel
Stand.................................................................................................................................................... Cast Iron
Paint Type/Finish...................................................................................................................................... Epoxy
Other
Bed Width.............................................................................................................................................. 7-1/4 in.
Floor To Center Height........................................................................................................................ 46-1/4 in.
Carriage Leadscrew Diameter.............................................................................................................. 0.870 in.
Carriage Leadscrew TPI............................................................................................................................ 8 TPI
Carriage Leadscrew Length....................................................................................................................... 44 in.
Cross Slide Leadscrew Diameter............................................................................................................. 3/8 in.
Cross Slide Leadscrew TPI...................................................................................................................... 16 TPI
Cross Slide Leadscrew Length.............................................................................................................. 9-1/2 in.
Coolant System.............................................................................................................................................. No
Other Specifications:
Country of Origin ................................................................................................................................................ China
Warranty ........................................................................................................................................................... 1 Year
Approximate Assembly & Setup Time ...................................................................................................... 1-1/2 Hours
Serial Number Location ........................................................................................................... ID Label on Headstock
ISO 9001 Factory .................................................................................................................................................... No
Certified by a Nationally Recognized Testing Laboratory (NRTL) .......................................................................... No
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Model G0791 (Mfd. Since 9/15)
Page 13
SECTION 1: SAFETY
Safety Instructions for Machinery
Model G0791 (Mfd. Since 9/15)
-11-
Page 14
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Model G0791 (Mfd. Since 9/15)
Page 15
Additional Safety for Metal Lathes
Model G0791 (Mfd. Since 9/15)
-13-
Page 16
Additional Safety for Mills
-14-
Model G0791 (Mfd. Since 9/15)
Page 17
Additional Lathe Chuck Safety
Model G0791 (Mfd. Since 9/15)
-15-
Page 18
SECTION 2: POWER SUPPLY
Availability
Full-Load Current Rating
Circuit Requirements for 220V
Nominal Voltage .............................. 220V/240V
Cycle ..........................................................60 Hz
Phase .................................................... 1-Phase
Power Supply Circuit ......................... 15 Amps
Plug/Receptacle ............................. NEMA 6-15
Cord ........“ S”-Type, 3-Wire, 14 AWG, 300 VAC
Full-Load Current Rating at 220V .... 8.5 Amps
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Model G0791 (Mfd. Since 9/15)
Page 19
Grounding Instructions
Figure 6. Typical 6-15 plug and receptacle.
Extension Cords
Minimum Gauge Size ...........................14 AWG
Maximum Length (Shorter is Better).......50 ft.
Model G0791 (Mfd. Since 9/15)
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Page 20
SECTION 3: SETUP
Preparation
The list below outlines the basic process of preparing your machine for operation. Specific steps
are covered later in this section.
The typical preparation process is as follows:
1. Unpack lathe/mill and inventory contents.
2. Clean lathe/mill and its components.
3. Identify an acceptable location for lathe/mill
and move it to that location.
4. Mount lathe/mill on stand and bolt it to floor.
5. Assemble loose components and make any
necessary adjustments or inspections to
ensure lathe/mill is ready for operation.
6. Check lathe/mill for proper lubrication.
7. Connect lathe/mill to power source.
8. Test run lathe/mill to ensure it functions
properly.
9. Perform spindle break-in procedure to prepare lathe/mill for operation.
Needed for Setup
The following are needed to complete the setup
process, but are not included with your machine.
• For Lifting and Moving:
— A forklift or other power lifting device rated
for at least 2000 lbs.
— Two lifting straps rated for at least 2000
lbs. each
— Lifting chain and safety hook rated for at
least 2000 lbs. each
— Another person to guide machine
• For Power Connection:
— A power source that meets the minimum
circuit requirements for this machine
(review Power Supply on 16 for details)
— An electrician or qualified service person-
nel to ensure a safe and code-compliant
connection to the power source
Unpacking
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• For Assembly:
— Shop rags
— Cleaner/degreaser (see Page 20)
— Quality metal protectant lubricant
— Safety glasses for each person
— Anchoring hardware as needed (see
Page 25)
— Precision level at least 12" long
Model G0791 (Mfd. Since 9/15)
Page 21
Inventory
Y. Drill Chuck B16 3-16mm ............................. 1
Z. Spindle Sleeve MT3 x MT2 ........................ 1
AA. Live Center MT#3 ....................................... 1
AB. Standard Dead Center MT#3 ..................... 1
AC. Carbide-Tipped Dead Center MT#3 ........... 1
AD. Fasteners (Not Shown):
—Hex Bolts M12-1.75 x 40 ......................... 6
—Flat Washers 12mm ................................ 6
—Phillips Head Screws M6-1 x 10 ............. 8
—Hex Nuts M6-1 ........................................ 4
—Flat Washers 6mm ................................. 8
Major Components (Figure 7) Qty.
A. Three-Jaw Chuck 6" w/Jaws ...................... 1
B. Follow Rest ................................................. 1
C. Steady Rest ................................................ 1
D. Backsplash ................................................. 1
E. Ta i l stock ...................................................... 1
F. Stand:
—Cabinets (Left & Right) ........................... 2
—Front Panel ............................................. 1
—Front Panel Brackets .............................. 2
G. Quick-Change Tool Post ............................ 1
Loose Components (Figure 8)
H. Faceplate 10" .............................................. 1
I. Toolbox ....................................................... 1
J. Bottle for Oil ............................................... 1
K. Four-Jaw Independent Chuck 8"
w/Camlock Studs and Cap Screws ............ 1
l. Chuck Wrench ............................................ 2
M. Phillips & Flat Screwdrivers #2 ..............1 Ea
N. Handwheel Handles ................................... 2
O. Tailstock Wrench ........................................ 1
P. Wrenches
Q. Hex Wrench Set 2, 4, 5, 6, 8, 10mm .....1 Ea
R. Drawbar ...................................................... 1
S. Drill Chuck Key
T. Quick-Change Tool Holder ......................... 1
U. Change Gears ............................................ 1
—Gear 27-tooth .......................................... 1
—Gear 26-tooth ......................................... 1
—Gear 35-tooth ......................................... 1
—Gear 36-tooth ......................................... 1
—Gears 40-tooth (Installed) ....................... 2
—Gear 45-tooth ......................................... 1
—Gear 50-tooth ......................................... 1
—Gear 60-tooth ......................................... 1
—Gear 86/91-tooth (Installed) .................... 1
V. Drill Chuck Arbor R8 x B16 ........................ 1
W. Spindle Sleeve R8 x MT3 ........................... 1
X. Spindle Sleeve MT5 x MT3 ........................ 1
9
⁄11, 10⁄12, 12⁄14, 17⁄19, 22⁄24 mm .....1 Ea
5
⁄16" STD 11T SD-5⁄8" ......... 1
B
A
C
D
E
G
F
Figure 7. Major components.
AB
J
N
K
L
M
H
W
V
S
R
Y
T
Q
Figure 8. Loose components.
I
X
Z
P
AA
AC
U
O
Model G0791 (Mfd. Since 9/15)
-19 -
Page 22
Cleanup
T23692—Orange Power Degreaser
A great product for removing the waxy shipping
grease from your machine during clean up.
Figure 9. T23692 Orange Power Degreaser.
-20-
Model G0791 (Mfd. Since 9/15)
Page 23
Site Considerations
30" Minimum
Clearance for
Maintenance
Keep
Workpiece
Loading Area
Unobstructed
Figure 10. Minimum working clearances.
Model G0791 (Mfd. Since 9/15)
Wall
271⁄2"
66"
Not to Scale
-21-
Page 24
Assembly
Assembling the Model G0791 consists of building the stand assembly, attaching the handwheel
handles, placing and securing the lathe on the
stand, anchoring the stand to the floor, attaching
the back splash, and installing the drawbar.
3. Remove crate from lathe shipping pallet, then
remove all loose items.
Important: Lifting and placing the lathe
requires at least one other person for assistance and a forklift with two lifting straps, lifting chain, and a safety hook rated for at least
2000 lbs. each.
4. Move lathe to its prepared location while it is
still attached to shipping pallet.
5. Unbolt lathe from shipping pallet.
6. Attach handles to cross slide and carriage
handwheels (see Figure 12).
Handwheel
Handles
To assemble machine:
1. Position left and right cabinets approximately
34" apart in prepared location.
2. Secure front panel brackets to cabinets with
(4) M6-1 x 10 Phillips head screws and (4)
6mm flat washers (see Figure 11).
Brackets
x 4
Cabinets
Figure 11. Brackets installed (rear view).
Figure 12. Handwheel handles attached.
7. To balance load for lifting, move tailstock and
carriage to right end of bedway, then lock
them in place.
Note: Before attempting to move the carriage,
make sure the carriage lock is loose, the half
nut is disengaged, and the feed selection
lever is disengaged. Refer to Controls &
Components, beginning on Page 5, to identify these components.
-22-
Model G0791 (Mfd. Since 9/15)
Page 25
8. Remove headstock end cover to protect it
during lifting and to gain better access to
headstock base pedestal (see Figure 13).
Headstock Pedestal
Mounting Points
12. Apply a 1⁄4" bead of silicone around bottom
edge of bedway pedestals.
Note: When the lathe is placed onto the chip
pan, the silicone will form a protective seal to
help prevent fluid leaking into the cabinets.
13. Place lathe on stand while aligning mounting
holes in lathe bed with holes in chip pan.
14. Insert (6) M12-1.75 x 40 hex bolts with (6)
12mm flat washers through pedestals and
chip pan, then partially thread them into
cabinet tops. Do not fully tighten them until
insructed
Figure 13. End cover removed for protection and
to expose headstock pedestal mounting points.
9. Wrap two lifting straps around bedway pedestals and route them behind control rod,
feed rod, and leadscrew, as shown in Figure
14. This will keep lifting straps away from
these critical components and prevent them
from bending during lifting.
Lifting
Sling
Note: For best results, recheck the ways in
24 hours to make sure they are still level and
have not twisted. Reshim as required.
15. Install front panel on panel brackets with (4)
M6-1 x 10 Phillips head screws, (4) 6mm
flat washers, and (4) M6-1 hex nuts (see
Figure 15).
Front Panel
Figure 15. Front panel installed.
Figure 14. Example of lifting slings positioned
correctly on a similar machine.
10. Position chip pan on top of cabinet stand
and align six mounting holes with those in
cabinets.
11. Have another person hold onto lathe to prevent it from swinging as you slowly raise lathe
from pallet and move it over stand.
Model G0791 (Mfd. Since 9/15)
-23-
Page 26
Recommended: Use mounting holes in cabi-
nets (see Figure 16) to mark holes in floor.
Lift machine/stand assembly out of the way
to drill holes, then re-position and anchor
assembly to floor. Shim between lathe and
chip pan as necessary to level ways at all
four corner locations. Refer to Anchoring to
Floor and Leveling on Page 25 for detailed
information.
19. Remove drawbar cap from mill headstock
(see Figure 18).
Drawbar
Cap
Figure 18. Location of drawbar cap.
Mounting
Holes
Figure 16. Locations of cabinet mounting holes
(two on each cabinet).
16. Fully tighten hex bolts from Step 14 to secure
lathe/mill to cabinet stand.
Tip: For best results, recheck the ways in 24
hours to make sure they are still level and
have not twisted. Re-shim as required.
17. Apply bead of silicone around pedestals,
where they contact chip tray, to further reduce
possibility of fluids leaking into cabinets.
18. Attach back splash to rear of lathe with (4)
M6-1 x 10 Phillips head screws and (4) 6mm
flat washers, as shown in Figure 17.
20. Insert threaded end of drawbar into mill headstock (see Figure 19).
Figure 19. Inserting drawbar into mill headstock.
21. Replace drawbar cap over head of drawbar.
Do not overtighten.
Note: Purpose of drawbar cap is to secure
drawbar without restricting its rotation. If necessary, loosen drawbar cap slightly until you
can rotate drawbar by hand.
x 4
Figure 17. Locations to secure back splash.
-24-
Model G0791 (Mfd. Since 9/15)
Page 27
Anchoring to Floor
Anchoring to Concrete Floors
Leveling
For accurate turning results and to prevent
warping cast iron bedways, lathe bedways
MUST be leveled from side to side and from
front to back on both ends.
Recheck bedways 24 hours after installation,
two weeks after that, and then annually to
make sure they remain level.
Leveling machinery helps precision components,
such as bedways, remain straight and flat during
the lifespan of the machine. Components on a
machine that is not level may slowly twist due to
the dynamic loads placed on the machine during
operation.
If needed, use metal shims between the lathe bed
and chip pan when leveling the machine.
Figure 20. Popular method for anchoring
machinery to a concrete floor.
For best results, use a precision level that is at
least 12" long and sensitive enough to show a
distinct movement when a 0.003" shim (approximately the thickness of one sheet of standard
newspaper) is placed under one end of the level.
See the figure below for an example of a high
precision level offered by Grizzly.
Figure 21. Model H2683 Master Machinist's
Level.
Model G0791 (Mfd. Since 9/15)
-25-
Page 28
Lubricating Lathe
Power Connection
Electrocution or fire
may occur if machine is
ungrounded, incorrectly
connected to power, or
connected to an undersized
circuit. Use an electrician
or a qualified service
personnel to ensure a safe
power connection.
The headstock, quick-change gearbox, and apron
oil reservoirs must have the proper amount of oil
in them before the lathe can be operated.
Damage caused to the bearings and gears from
running the lathe without oil in the reservoirs
will not be covered under warranty. Refer to the
Lubrication section, beginning on Page 77, for
checking and adding oil.
In addition to the reservoirs, we also recommend
that you lubricate all other points on the machine
at this time.
Note: If this lathe was shipped with oil in the
reservoirs, do not change that oil until after the
test run and spindle break-in procedures.
Before the machine can be connected to the
power supply, there must be an electrical circuit
that meets the Circuit Requirements for 220V
on Page 16.
To minimize the risk of electrocution, fire, or equipment damage, installation work and electrical wiring MUST be done by an electrician or qualified
service personnel.
Note About Extension Cords: Using an incor-
rectly sized extension cord may decrease the life
of electrical components on your machine. Refer
to Extension Cords on Page 17 for more information.
-26-
Model G0791 (Mfd. Since 9/15)
Page 29
To connect power cord to machine:
1. Press Emergency Stop/RESET button on
front of headstock, then remove electrical box
cover from back.
2. Thread power cord through strain relief shown
in Figure 22.
Incoming Power
Strain Relief
4. Make sure wires have enough slack between
strain relief and terminal connections so they
are not pulled tight or stretched, then tighten
strain relief to secure cord.
Note: The strain relief must be tightened
against the outer jacket of the cord. Avoid
over-tightening the strain relief or it may
crush the cord and cause a short.
5. Test strain relief to ensure it is properly tightened by pulling cord from outside box with
light-to-moderate force. When strain relief is
properly tightened, cord will not move inside
cabinet.
6. Install NEMA 6-15 plug on other end of power
cord per plug manufacturer's instructions.
7. Re-install main electrical box cover.
Figure 22. Location of incoming power strain
relief.
3. Identify L and N terminals and grounding
terminal (PE), illustrated in Figure 23, then
connect incoming hot wires and ground wire
to those terminals.
Ground
PE
L N
To
Power Source
To avoid unexpected start-up, keep
Emergency Stop/RESET button pressed in
until instructed otherwise in Test Run.
8. Plug cord into matching power supply recep-
tacle and power source as specified in Circuit
Requirements for 220V on Page 16.
Figure 23. Incoming power wires connected
inside electrical cabinet.
Model G0791 (Mfd. Since 9/15)
-27-
Page 30
Test Run
Disengaged
The test run consists of verifying the following: 1)
The motor powers up and runs correctly, 2) the
emergency stop/RESET button safety feature
works correctly.
To test run machine:
1. Make sure chuck and jaws, if installed, are
secure (refer to Chuck Installation on Page
34).
Note: If chuck is not installed on lathe, you do
not need to install one for this test.
2. Make sure spindle lever is in OFF (center)
position (see Figure 24).
3. To ensure carriage components do not unexpectedly move during following steps, disengage half nut lever and apron feed selection
lever (see Figure 24).
Half-Nut Lever
is Pulled Up
(Disengaged)
Feed Selection
Lever is
Horizontal
(Disengaged)
Cross Slide
Carriage
Feed Selection
Lever
Figure 24. Disengaging carriage components.
4. Rotate Emergency Stop/RESET button clock-
wise so it pops out. Power lamp on control
panel should illuminate.
Spindle Lever
(OFF, Center
Position)
Disengaged
Halfnut
Lever
Engaged
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Model G0791 (Mfd. Since 9/15)
Page 31
5. Select spindle speed of 70 RPM by moving spindle speed levers to B and
I (see
Figure 25).
6. Move Mill FWD/REV switch (see Figure 25)
to "Mill" position, enabling power to lathe.
Speed Levers
— If spindle rotation does start with RESET
button pressed in, the Emergency Stop/
RESET button safety feature is not
operating correctly. This safety feature
must operate properly before continuing
operation. Use spindle lever to stop lathe,
disconnect it from power, and call Tech
Support for help.
9. Move spindle lever to OFF (center) position,
and reset Emergency Stop/RESET button by
twisting it clockwise until it pops out.
10. Set mill spindle speed shift levers to 250
RPM, according to chart on front of mill headstock (see Figure 26).
Note: You must pull each lever out slightly
before rotating, then push back in to secure.
Tip: If a shift lever seems stuck or difficult
to move, manually rotate the spindle until
internal headstock gears mesh, and the lever
moves freely.
Figure 25. Lathe headstock controls.
7. Push POWER START button, then move
spindle lever (see Figure 24 on Page 28)
down to start forward spindle rotation. Top of
chuck should turn down and toward front of
lathe.
— When operating correctly, machine will
run smoothly with little or no vibration or
rubbing noises.
— Investigate and correct strange or unusual
noises or vibrations before operating
machine further. Always disconnect
machine from power when investigating or
correcting potential problems.
8. Push Emergency Stop/RESET button to turn
lathe OFF, then, without resetting Emergency
Stop/RESET button, try to restart spindle
rotation, as instructed in Step 7. Spindle
should not start.
Spindle
Spindle Speed
Shift Levers
250
530
Speed
Chart
1100
2300
Figure 26. Mill spindle speed set to 250 RPM.
Model G0791 (Mfd. Since 9/15)
-29-
Page 32
11. Move Mill FWD/REV switch (see Figure 25,
Page 29) to FWD position.
12. Push POWER START button. Mill spindle
should begin to rotate.
— When operating correctly, machine will
run smoothly with little or no vibration or
rubbing noises.
— Investigate and correct strange or unusual
noises or vibrations before operating
machine further. Always disconnect
machine from power when investigating or
correcting potential problems.
13. Move Mill FWD/REV switch to "Mill" position
(see Figure 25 on Page 29) to turn mill OFF.
14. Move Mill FWD/REV switch to REV position,
repeat Step 12, then push Emergency Stop/
RESET button to turn mill OFF.
Spindle Break-In
15. Without resetting Emergency Stop/RESET
button, try to restart spindle rotation, as
instructed in Step 12. Spindle should not
start.
— If spindle rotation does start with RESET
button pressed in, RESET button safety is
not operating correctly. This safety feature
must operate properly before continuing
operation. Disconnect machine from power,
and call Tech Support for help.
Congratulations! The test run is complete. Perform
the following Spindle Break-In procedure.
To perform spindle break-in:
1. Successfully complete Test Run procedure
beginning on Page 28.
2. Run lathe spindle at 70 RPM for 10 minutes
in each direction (first forward, then reverse).
3. Turn lathe OFF. Move lathe spindle speed
levers to C and 1 for 200 RPM, then run lathe
for 5 minutes in each direction.
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Model G0791 (Mfd. Since 9/15)
Page 33
4. Repeat Step 3 for following speeds, progressing from lower to higher RPMs (see
Setting Spindle Speed on Page 51 for more
information):
Recommended
Adjustments
• 360 RPM
• 800 RPM
• 1400 RPM
5. Press Emergency Stop/RESET button to turn
lathe OFF. Reset switch.
6. Run mill spindle at 250 RPM for 10 minutes
in each direction (first forward and then
reverse).
7. Turn mill OFF to stop spindle rotation.
8. Repeat Steps 6–7 for following speeds (see
Setting Spindle Speed on Page 51 for more
information):
• 530 RPM
• 1100 RPM
• 2300 RPM
9. Press Emergency Stop/RESET button to turn
machine OFF.
The following adjustments have been made at the
factory. However, because of the many variables
involved with shipping, we recommend that you
at least verify the following adjustments to ensure
the best possible results from the lathe.
Step-by-step instructions for these adjustments
can be found on the pages referenced below.
Factory adjustments that should be verified:
• Tailstock alignment (see Page 41).
• Backlash adjustment (see Page 86).
• Gib adjustments (see Page 87).
Congratulations! The spindle break-in is complete. We recommend changing the headstock
and gearbox oil before operating the machine
further (refer to Lubrication on Page 77).
DO NOT attempt to change mill spindle
speed while spindle is in motion. Doing
so can cause catastrophic damage to mill
headstock gears and components.
Model G0791 (Mfd. Since 9/15)
-31-
Page 34
SECTION 4: LATHE OPERATIONS
To complete a typical lathe operation, the
Operation Overview
operator does the following:
1. Examines workpiece to make sure it is suit-
able for turning, then securely mounts it in
lathe.
2. Installs tooling, aligns it with workpiece, then
backs it away to establish a safe startup
clearance.
3. Removes all setup tools from lathe.
4. Checks for safe clearances by rotating
workpiece by hand at least one full revolution.
5. Moves slides to where they will be used during operation.
To reduce risk of eye or face injury from
flying chips, always wear approved safety
glasses and face shield when operating this
machine.
6. Sets correct spindle speed for operation.
7. If using power feed, selects proper feed rate
for the operation.
8. Puts on safety glasses, rolls up sleeves,
removes jewelry, and secures any clothing,
jewelry, or hair that could get entangled in
moving parts.
9. Resets Emergency Stop/RESET button, then
starts spindle rotation.
10. Uses carriage handwheels or power feed
options to move tooling into workpiece for
operations.
11. When finished cutting, moves spindle lever to
OFF position, waits for spindle to completely
stop, then removes workpiece.
-32-
Model G0791 (Mfd. Since 9/15)
Page 35
Chuck & Faceplate
Chuck Safety &
Mounting
Support Devices
Model G0791 (Mfd. Since 9/15)
Figure 27. Examples of common devices used
during chuck installation and removal.
-33-
Page 36
Chuck Installation
Figure 29. Cam line positioned between the "V"
marks after the camlocks are fully tightened.
Figure 28. Inserting camlock studs into spindle
cam holes.
-34-
Figure 30. Correcting an improperly installed
stud.
Model G0791 (Mfd. Since 9/15)
Page 37
Chuck Removal
Registration Marks
Figure 31. Registration mark locations.
Figure 32. Camlock is fully loosened when the
cam line is aligned with the spindle mark.
Model G0791 (Mfd. Since 9/15)
-35-
Page 38
Scroll Chuck
Clamping
Chuck Jaw Reversal
Figure 33. Jaw selection and workpiece holding.
-36-
Figure 34. Reversing the chuck jaws.
Model G0791 (Mfd. Since 9/15)
Page 39
4-Jaw Chuck
Figure 35. 4-jaw tightening sequence.
Model G0791 (Mfd. Since 9/15)
Figure 36. Example of a non-cylindrical
workpiece correctly mounted on a 4-jaw chuck.
-37-
Page 40
Faceplate
Non-Cylindrical
Workpiece
Clamp
Faceplate
Figure 37. Generic picture of workpiece clamped
in a faceplate.
-38-
Model G0791 (Mfd. Since 9/15)
Page 41
Tailstock
Quill Handwheel Graduated Dial
Increments ................................................. 0.001"
One Full Revolution ................................... 0 .100"
Increments on Quill
Inch ...........................0"–4 " in 0.100" Increments
Positioning Tailstock
Optional: To precisely secure the tailstock, mount
1
⁄2 " drive torque wrench in the square drive
a
shown in Figure 38, then tighten the tailstock to
40 lb/ft of torque. The center point will be drawn
down as much as 0.006". Do not exceed the max
torque or damage to ways and tailstock will occur.
Quill Lock
Lever
1
⁄2" Square Drive
Lock-Down
Figure 38. Tailstock and quill lock levers in
locked position.
Tailstock Lock
Lever
Quill Handwheel
Using Quill
Model G0791 (Mfd. Since 9/15)
-39-
Page 42
Installing Tooling
Solid
End
Figure 39. Types of tapered arbors and tooling.
Open
End
Tang
Solid
End
Screw
End
Tang
Removing Tooling
Figure 40. Example photos of inserting tools
with tangs into the tailstock.
-40-
Drift Key Slot
Figure 41. Drift key slot in the side of the quill.
Model G0791 (Mfd. Since 9/15)
Page 43
Offsetting Tailstock
Adjustment
Set Screw
(1 of 2)
Aligning Tailstock to Spindle
Centerline
Items Needed Qty
Hex Wrench 4mm .............................................. 1
Round Stock 2" x 6" .......................................... 2
Precision Level .................................................. 1
Offset
Indicator
Figure 42. Left offset adjustment.
Tools Needed Qty
Hex Wrench 4mm .............................................. 1
Figure 44. Turning a dead center.
Figure 43. Set screw adjustment in relation to
tailstock movement.
Model G0791 (Mfd. Since 9/15)
-41-
Page 44
Figure 45. Example of stock mounted between
centers on a typical lathe.
Figure 46. Adjust tailstock toward the operator.
Figure 47. Adjust tailstock away from the
operator.
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Model G0791 (Mfd. Since 9/15)
Page 45
Centers
Figure 48 shows the MT#3 dead centers and
live center included with the lathe. In addition, an
MT#5–MT#3 tapered spindle sleeve is included
for mounting in the spindle.
Live Centers
Mounting Dead Center in Spindle
Adapter
Sleeve
Figure 48. Adapter sleeve and centers.
Dead
Center
Carbide-Tipped
Dead Center
Dead Centers
Live
Center
Dead Center
Model G0791 (Mfd. Since 9/15)
Lathe
Dog
Figure 49. Example of using a dead center with
a faceplate and lathe dog.
-43-
Page 46
Removing Center from Spindle
Mounting Center in Tailstock
Carbide-Tipped
Dead Center
Note: The maximum quill travel is 4", but
we do not recommend extending the quill
more than 2" or stability and accuracy will be
reduced.
Figure 50. Example of using a carbide-tipped
dead center installed in the tailstock.
Removing Center from Tailstock
Drift Key Slot
-44-
Figure 51. Typical drift key slot in the side of a
quill.
Model G0791 (Mfd. Since 9/15)
Page 47
Mounting Workpiece Between
Centers
Joining Drill Chuck
& Arbor
Figure 52. Example of a workpiece mounted
between centers on a typical lathe.
Model G0791 (Mfd. Since 9/15)
Figure 53. Tapping drill chuck/arbor on block of
wood to seat it.
-45-
Page 48
Steady Rest
Tools Needed for Installation/Removal Qty
Hex Wrench 3mm .............................................. 1
Open-End Wrench 10 mm .................................. 1
Open-End Wrench 19 mm .................................. 1
Finger
Adjustment
Knob
Set Screw &
Jam Nut
Finger
Roller
Clamp
Knob
Figure 54. Steady rest components.
To in stall and use steady rest:
1. DISCONNECT LATHE FROM POWER!
2. Thoroughly clean all mating surfaces, then
place steady rest base on bedways so triangular notch fits over bedway prism.
Hex Nut
4. Loosen clamp knob that secures the two
halves of steady rest and open top portion,
as shown in Figure 55.
Figure 55. Workpiece mounted in the steady
rest.
5. Loosen jam nuts and set screws so finger
roller positions can be adjusted.
6. Use finger adjustment knobs to position bottom two finger rollers against workpiece.
7. Close steady rest, then use finger adjustment
knobs to adjust all three finger rollers so that
they just touch the workpiece without causing
deflection.
Note: The finger rollers should properly sup-
port the workpiece along the spindle centerline while still allowing it to freely rotate.
8. Lock fingers with set screws and jam nuts,
then tighten clamp knob.
3. Position steady rest with base clamp where
required to properly support workpiece, then
tighten hex nut shown in Figure 54 to secure
it in place.
-46-
Note: To reduce the effects of friction, lubri-
cate the finger rollers with way oil before
operation.
Model G0791 (Mfd. Since 9/15)
Page 49
Follow Rest
Compound Rest
The compound rest is used to move the tool
toward and away from the workpiece at the preset
angle of the compound rest. The base of the compound rest has graduated scale used for setting
the cutting tool to a specific angle.
Tip: To reduce the effects of friction, lubricate the
finger rollers with way oil before operation.
Finger
Rollers
Cap
Screws
Figure 56. Follow rest attachment.
Carriage & Slide
Locks
Graduated Dial
Increments ................................. 0.001" (0.05mm)
One Full Revolution ........................0.200" (5mm)
Tool Needed Qty
Wrench 14mm ................................................... 1
To set compound rest at a certain angle:
1. Loosen two hex nuts at base of compound
rest (see Figure 58).
Hex Nuts
Angle
Scale
The carriage, cross slide, and compound rest
have locks (see Figure 57) that can be tightened
to provide additional rigidity during operation.
Tools Needed Qty
Hex Wrench 3mm .............................................. 1
Hex Wrench 6mm .............................................. 1
Carriage
Lock
Compound Rest
Lock
Figure 57. Locations of compound rest, carriage,
and cross slide locks.
Model G0791 (Mfd. Since 9/15)
Cross Slide
Lock
Figure 58. Location of angle scale and rotation
hex nuts on the compound rest.
-47-
Page 50
2. Rotate rest to desired angle, as indicated by
scale, then retighten the two hex nuts.
Tip: Use an angle gauge to initially set the
compound rest at 60° for threading, then
mark the cross slide at the 0° mark on the
scale for future reference (see Figure 59).
Angle Gauge
Figure 59. Using an angle gauge to set
compound rest to 60° for threading.
Compound Rest
Location For
Reference
Mark
Tool holders can be quickly loaded and unloaded
using the lock lever, and rotated by loosening the
top nut. Tools up to
ing the tool holder set screws. The thumb wheel
rotates to adjust cutting tool height.
5
⁄8" can be secured by tighten-
Installing Tool
Tools Needed Qty
Open-End Wrench/Socket 27mm ...................... 1
Hex Wrench Size 5mm ...................................... 1
Tool Post
Figure 60. Example of tool mounted in tool post.
-48-
Model G0791 (Mfd. Since 9/15)
Page 51
Aligning Cutting Tool with Spindle
Centerline
Figure 61. Cutting tool aligned with spindle
centerline (viewed from tailstock).
Tools Needed Qty
Hex Wrench 5mm .............................................. 1
Open-End Wrench/Socket 27mm ...................... 1
Steel Shims ....................................... As Needed
Cutting Tool ....................................................... 1
Fine Ruler .......................................................... 1
Tailstock Center ................................................. 1
Model G0791 (Mfd. Since 9/15)
Figure 62. Cutting tool aligned to the tailstock
center.
-49-
Page 52
Spider
Manual Feed
This lathe is equipped with a set of outboard
spindle supports otherwise known as a "spider"
(see Figure 63).
Spider
Jam
Nut
Figure 63. Spider components.
Remove spider screws when not in use.
Always DISCONNECT LATHE FROM POWER
when installing, removing, or adjusting spider screws. Ignoring this warning can lead
to personal injury or machine damage.
Screw
The handwheels shown in Figure 64 allow the
operator to manually move the cutting tool.
Cross Slide
Carriage
Handwheel
Figure 64. Locations of carriage, cross slide,
and compound rest handwheels.
Handwheel
Compound Rest
Handwheel
Carriage Handwheel
Graduated Dial
Increments ................................... 0.01" (0.25mm)
One Full Revolution ................... 0.66" (16.76mm)
Use the carriage handwheel to move the carriage
left or right along the bed.
The spider is especially designed for supporting
gun barrels during chambering operations; however, it is a great support option for almost any
long workpiece that extends through the outboard
side of the spindle.
The tips of the spider screws have brass wear
pads that hold the workpiece without causing
indents in the finish.
When spider screws are installed, always use the
jam nuts to lock each spider screws in position.
Merely tightening the spider screws against the
workpiece and leaving the jam nuts loose is not
safe. Spiders screws that loosen during operation
can crash into the end gear cover.
Cross Slide Handwheel
Graduated Dial
Increments .................................0.002" (0.05mm)
One Full Revolution ................... 0.100" (2.54mm)
Adjust the position of the graduated scale by holding the handwheel with one hand and turning the
dial with the other. The cross slide handwheel
has a direct-read graduated dial, which shows the
total amount of material removed from the diameter of the workpiece.
Compound Rest Handwheel
Graduated Dial
Increments ................................ 0.001" (0.03mm)
One Full Revolution ................... 0.100" (2.54mm)
Use this handwheel to move the cutting tool linearly along the set angle of the compound rest.
The compound rest has an indirect-read graduated dial, which shows the actual distance the
tool moves.
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Model G0791 (Mfd. Since 9/15)
Page 53
Spindle Speed
Determining Spindle Speed
Setting Spindle Speed
The alpha and numeric spindle speed levers,
shown in Figure 66, are used to select one of the
nine spindle speeds.
Numeric
Alpha
Lever
Figure 66. Spindle speed levers.
The spindle speed levers control the gear configuration in the headstock to produce the selected
spindle speed.
Lever
Figure 65. Spindle speed formula for lathes.
To avoid damaging gears, ALWAYS make
sure the spindle is completely stopped
BEFORE moving the spindle speed levers.
The chart below shows the various combinations
of lever positions for achieving a desired speed.
Spindle Speed RPM
I II III
A
B
C 200 1000 600
Figure 67. Spindle speed chart.
8001400270
22036070
Model G0791 (Mfd. Since 9/15)
-51-
Page 54
Configuration Example
Figure 68 shows the levers positioned for a
spindle speed of 600 RPM.
Note: If the spindle speed levers do not easily
adjust into position, rotate the spindle by hand
while you apply pressure to the lever. When the
gears align, the lever will easily move into place.
If you have trouble rotating the spindle by hand,
you can use the spindle key or a chuck key to get
additional leverage—just be sure to remove the
key when you are done.
Alpha
Lever
Set to "C"
Numeric
Lever
Set to "III"
Understanding Gear
Charts
This subsection explains how to understand the
feed and thread charts on the headstock. If you do
not understand lathe gear charts, or need a quick
refresher, read this before configuring the end
gears for power feeding or threading operations.
Feed & Threading Chart Labels
The feed and thread chart labels (see Figure 69)
provide information for setting up end gears and
gearbox levers for threading or non-threading
operations.
C
B
A
Spindle Speed RPM
I II III
A
B
C 200 1000
Figure 68. Setting the spindle speed to 600
RPM.
I
I
I
I
I
I
8001400270
22036070
600
Metric Threading
Chart Label
Feed Chart
Label (On
Left Side of
End Gear
Cover)
Figure 69. Feed and thread charts label.
Feed Chart—Displays gearbox dial positions for
different speeds of automatic feed (power feed)
used with turning operations (see Figure 70).
Inch Threading
Chart Label
Gearbox
Levers
-52-
Figure 70. Feed rate chart.
Model G0791 (Mfd. Since 9/15)
Page 55
Metric Threading Chart—Displays headstock
end gear positions used for cutting various metric
threads (see Figure 71).
How to Read Feed Chart
Figure 73 identifies the forty available metric and
inch feed rates for each longitudinal and transverse carriage movement, and shows the end
gear positions for feeding.
The end gears for all feeding operations must be
arranged as follows (see End Gears on Page 58
for more information):
• 40T gear in the upper position
• 86T gear in the middle position
• 40T gear in the lower position
EndGear
Setup
Feed
Rates
Figure 71. Metric threading chart.
Inch Threading Chart—Displays headstock end
gear and gearbox lever positions used for cutting
various inch threads (see Figure 72).
40T
86T
40T
Figure 72. Inch threading chart.
Figure 73. Available feed rates and end gear
positions for feeding.
Model G0791 (Mfd. Since 9/15)
-53-
Page 56
Figure 74 indicates that for a longitudinal feed
rate of 0.0096 in/rev., the alpha feed lever must
be set to "B", and the numeric feed lever set to "7"
(see Figure 75).
How to Read Metric Threading Chart
Figure 76 indicates the gearbox lever and end
gear positions, and available pitches, for metric
threading.
Alpha Feed
Lever Set to B
Longitudinal
Feed Icon
Figure 74. Reading feed chart.
Alpha Lever
Set to B
Numeric Feed
Lever Set to 7
Numeric Lever
Set to 7
Feed Rate
.0096 in/rev.
Numeric
Lever
Positions
Metric
Thread
Pitches
Alpha
End Gear
Positions
Figure 76. Location of gearbox lever and end
gear positions on metric threading chart.
Lever
Positions
Figure 75. Feed levers set to "B" and "7" for
0.0096 in/rev. longitudinal feed rate.
Figure 77 shows how the gearing illustrations in
the thread chart relate to the end gears.
Figure 77. Power feed gearing setup.
-54-
Model G0791 (Mfd. Since 9/15)
Page 57
How to Read Inch Threading Chart
Figure 78 indicates the gearbox lever and end
gear positions and available TPI for inch threading.
Power Feed
The end gears for all inch threading operations
must be arranged as follows (see End Gears on
Page 58 for more information):
• 40T gear in upper "F" position
• 86T/91T gear in middle position, with 86T
gear mounted toward lathe
• 40T gear in lower "G", inside position
End Gear Positions
40T
86T
40T
Alpha Lever
Positions
Figure 78. Location of gearbox lever and end
gear positions on inch threading chart.
Numeric Lever Positions
Threads Per Inch
Both the carriage and cross slide have power feed
capability when the carriage is engaged with the
feed rod. The rate that these components move
per revolution of the feed rod is controlled by the
quick-change gearbox lever positions and the end
gear configuration.
The feed per revolution and the spindle speed
must be considered together—this is the feed
rate. The sources you use to determine the optimum spindle speed for an operation will also
provide the optimal feed to use with that spindle
speed.
Often, the experienced machinist will use the
feeds and speeds given in their reference charts
or web calculators as a starting point, then make
minor adjustments to the feed rate (and sometimes spindle speed) to achieve the best results.
The carriage can alternately be driven by the
leadscrew for threading operations. However, this
section only covers the use of the power feed
option for the carriage and cross slide components for non-threading operations. To learn how
to power the carriage for threading operations,
refer to Threading on Page 61.
Model G0791 (Mfd. Since 9/15)
If feed selection lever and half nut are
engaged at the same time, machine damage
could occur. Even though there is a lockout device to prevent this, it could break if
forced.
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Page 58
To avoid damaging lathe, spindle MUST be
completely stopped BEFORE using power
feed controls to make changes.
Power Feed Controls
Use Figures 79–80 and the following descrip-
tions to understand the power feed controls.
Note: Before using power feed, you may have to
reconfigure the end gears, depending on how they
are set up. Refer to End Gears on Page 58 for
detailed instructions.
The lathe comes from the factory with the end
gears set up in the power feed configuration.
A
B
C
D
Figure 80. Apron feed selection lever.
A. Feed Direction Lever: Selects the direction
for power feed. When the lever is positioned
as shown in Figure 79, the carriage will move
to the left along the bed, or the cross feed will
travel toward the rear of the lathe.
B. Headstock Feed Selection Lever: Selects
the leadscrew or feed rod for powered rotation. The center position is neutral and neither will move.
C. Quick-Change Gearbox Levers: Select the
rate of power feed.
D. Apron Feed Selection Lever: Changes the
power feed to either the carriage or cross
slide.
When the lever is down and the indent pin
is pointing up, the cross slide is selected.
Conversely, when the lever is up and the pin
is pointing down, the carriage is selected.
Figure 79. Headstock and quick-change gearbox
controls for power feed.
-56-
In the middle position, the apron gears are
disengaged from the feed rod and neither
component will move.
Note: When using this lever, you may need
to slightly rotate the handwheel of the component you are trying to engage, so that the
apron gears can mesh.
Model G0791 (Mfd. Since 9/15)
Page 59
Setting Power Feed Rate
The power feed rate chart in Figure 81 (also
located on the end gear cover) displays the end
gear and quick-change gearbox lever settings for
available feed rates.
2. Locate box in chart that lists a feed rate of
0.0021" in./rev. for cross slide (see Figure 82).
Setting for Gearbox Levers
Feed
Rate
Figure 82. 0.0021 in./rev feed rate displayed in
chart.
NOTICE
To prevent damage to gearbox components,
NEVER move levers while lathe is running,
and NEVER force any lever when shifting. If
lever will not engage, rotate chuck by hand
while keeping light pressure on lever. As
chuck rotates it aligns gears and lever will
engage.
Figure 81. Feed rate chart.
This symbol indicates longitudinal feed.
This symbol indicates cross feed rates.
Using the controls on the lathe, follow along with
the example below to better understand how to
set the lathe for the desired power feed rate.
Setting Cross Slide Power Feed Rate of 0.0021
in./rev.
1. Make sure end gears are set up as displayed
on left side of chart (refer to End Gears on
Page 58 for detailed instructions).
Note: The top half of the chart displays feed
rates in mm/rev., while the bottom half displays feed rates in in./rev.
3. Position lever pins in gearbox holes indicated
on chart.
— Pull knurled knob out to release lever pin
from hole.
— Lower lever below gearbox and slide it
directly under desired hole.
— While pulling knurled knob out, raise lever
so that pin is directly over hole, then
release knob to seat pin (see Figure 83 for
an example).
Model G0791 (Mfd. Since 9/15)
Figure 83. Example of gearbox lever pins seated
in holes.
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Page 60
4. Move headstock feed selection lever to left—
this selects feed rod rotation.
5. Use headstock feed direction lever to select
direction of cross feed travel.
When this lever is to right, cross slide will
travel away from operator; conversely, when
lever is to left, cross slide will travel toward
operator.
6. Push apron feed selection lever toward spindle, then shift it down to select cross slide for
power feed.
End Gears
This section explains how to configure end gears
for feeding and threading operations.
Primary Metric Threading
Configuration
This configuration is used for most metric threading. Mesh the "F" position gear with the 91T
change gear, and mesh the 86T change gear with
the "G" position gear in the "outside" position, as
shown in Figure 85.
Power Feed & Inch Threading
Configuration
The end gear configuration shown in Figure 84
is the same for all power feed and inch threading
operations.
86T Gear:
Toward Lathe
40T Gear:
F Position
40T Gear:
Inside G Position
Figure 84. End gear configuration for power
feeding and inch threading.
Mesh the 40T "F" position gear with the 86T
change gear, and mesh it with the 40T "G" position gear in the "inside" position.
Figure 85. Primary metric threading end gear
configuration.
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Model G0791 (Mfd. Since 9/15)
Page 61
Secondary Metric Threading
Configuration
This configuration is used for some metric threading. Use the 26T gear in the "F" position; orient
the 86T/91T change gear in any position, and use
the 60T gear in the inside "G" position, as shown
in Figure 86.
End-Gear Configuration Example
Follow the example below to better understand
how to configure the end gears for metric threading.
Tools Needed Qty
Hex Wrench 3mm .............................................. 1
Hex Wrench 5mm .............................................. 1
Wrench or Socket 17mm ................................... 1
To configure end gears for 2.25 metric thread
pitch:
1. DISCONNECT MACHINE FROM POWER!
2. Remove end gear cover.
3. Locate 2.25 on metric thread chart, then
locate 45T "F" position gear and 60T "G"
position gears in "F" and "G" gear columns,
and note position of 86T/91T change gear
(see Figure 87).
Figure 86. Secondary metric threading end gear
configuration.
"F" and "G"
Gear Columns
86T/91T
Change Gear
With 91T Gear
Toward Lathe
45T Gear
In "F" Position
2.25 Metric
Thread Pitch
60T Gear
In "G" Position
Figure 87. Configuring end gears for 2.25 metric
thread pitch.
Model G0791 (Mfd. Since 9/15)
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Page 62
4. While holding middle 86T/91T gear assembly
(see Figure 88), loosen support arm hex nut
and slowly let assembly pivot down.
F Gear
86T/91T
Middle Gear
Hex Nut
Gear
Support Arm
Hex Nut
G Gear
Figure 88. End gear components.
6. Replace F gear with 45T gear, and G gear
with 60T gear.
Note: The 60T gear (and 40T gear) used as
the G gear has a stepped face that allows it
to mesh with either the outside or inside teeth
of the middle gear, depending upon the configuration needed.
7. Secure F and G gears with fasteners, but do
not overtighten. The fasteners merely keep
them in place and overtightening may hinder
rotation.
8. Re-install 86T/91T middle gear with 91T gear
toward lathe, and slide it against G gear until
it meshes with a 0.002"–0.004" backlash,
then tighten middle gear hex nut.
5. Remove 86T/91T middle gear, then F and G
gears.
Note: Make sure the keys stay inserted in the
shafts as you slide the F and G gears off.
9. Pivot middle gear up against F gear until it
meshes with same backlash, then tighten
support arm hex nut.
10. Re-install end gear cover.
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Model G0791 (Mfd. Since 9/15)
Page 63
Threading
Lever
3. Locate 11 TPI and lever positions "B" and "5"
on chart (see Figure 89).
The following subsections will describe how to
use the threading controls and charts to set up the
lathe for a threading operation. If you are unfamiliar with the process of cutting threads on a lathe,
we strongly recommend that you read books,
review industry trade magazines, or get formal
training before attempting any threading projects.
Headstock Threading Controls
The threading charts on the headstock face display the settings for inch and metric threading.
Using the controls on the lathe, follow the example below to understand how to set up the lathe
for the desired threading operation.
To set up for a thread pitch of 11 TPI:
1. DISCONNECT MACHINE FROM POWER!
2. Install end gears as directed on inch thread
chart (see Figure 89 or the chart on gearbox).
4. Position gearbox lever pins in gearbox holes
indicated on chart—B and 5.
— Pull knurled knob out to release lever pin
from hole.
— Lower lever below gearbox and slide it
directly under desired hole.
— While pulling knurled knob out, raise lever
so that pin is directly over hole, then
release knob to seat pin.
5. Move headstock feed selection to left for
leadscrew rotation.
Apron Threading Controls
The half nut lever engages the carriage with the
leadscrew, which moves the carriage and cutting
tool along the length of the workpiece for threading operations (see Figure 90).
Important: Make sure the feed selection lever
is in the disengaged (center) position before
attempting to engage the half nut.
End Gear
Configuration
Position
"B"
11 TPI Position
40T
86T
40T
Figure 89. End gear and gearbox lever
configuration for 11 TPI.
"5"
Feed Selection
Lever
Cross Slide
Disengaged
Carriage
Feed Selection
Figure 90. Apron threading controls.
Half Nut
Lever
Disengaged
Engaged
Halfnut
Lever
Model G0791 (Mfd. Since 9/15)
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Page 64
Thread Dial
Tools Needed Qty
Hex Wrench 5mm .............................................. 1
Thread Dial Chart
The thread dial chart is located on the headstock,
as shown in Figure 92.
The numbers on the thread dial are used with the
thread dial chart to show when to engage the half
nut during inch threading. Loosen the cap screw
on the thread dial (see Figure 91), pivot the gear
teeth so they mesh with the leadscrew threads,
then retighten the cap screw.
Important: The thread dial is not used for metric
threading. For metric threading, you must leave
the half nut engaged, stop the spindle at the end
of each cut, retract the tool one full turn of the
cross slide, then run the lathe in reverse to reposition tool to the start of the threads.
Note: As a basic rule of thumb, you can always
cut any thread (other than metric or 4.75 TPI, by
starting on the number 1 of the thread dial.
Thread
Dial
Thread Dial
Chart
Figure 92. Location of thread dial chart.
Find the TPI (threads per inch) that you want to cut
in the left columns (under TPI), then reference the
dial number in the right columns (under Scale).
The dial numbers indicate when to engage the
half nut for a specific thread pitch as indicated by
the thread dial chart (see Figure 93).
Cap
Screw
Figure 91. Thread dial engaged with the
leadscrew.
When threading, we recommend using slowest speed possible and avoiding deep cuts,
so you are able to disengage half nut when
required and prevent an apron crash!
When the first thread cutting pass is complete,
the operator disengages the carriage from the
leadscrew using the half nut lever. The operator
returns the carriage for the next pass and reengages the half nut using the same thread dial
setting to resume the cut as in the previous pass.
INDICATOR TABLE
SCALE
TPI TPI TPI
4
4.5
4.75
5
5.5
6
6.5
7
8
9
9.5
10
11
12
1
1
1, 3
1
1-2-3-4
1
1, 3
1–8
1, 3
1
1-2-3-4
1, 3
1–8
SCALE SCALE
13
14
16
18
19
20
22
24
26
28
32
36
38
40
1, 31–8
1-2-3-4
1–8
1-2-3-4
1, 3
1–8
1-2-3-4
1–8
1-2-3-4
1–8
1–8
1–8
1-2-3-4
1–8
44
48
52
56
64
72
76
80
88
96
104
112
Figure 93. Thread dial chart.
1–8
1–8
1–8
1–8
1–8
1–8
1–8
1–8
1–8
1–8
1–8
1–8
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Model G0791 (Mfd. Since 9/15)
Page 65
The following examples explain how to use
1
2
3
4
SCALE
1–8
1
2
3
4
1
2
3
4
1
2
3
4
SCALE
ALL
SCALE
N
SCALE
1
1
2
3
4
1
2
3
4
SCALE
ALL
SCALE
N
the thread dial and the thread dial chart.
Even TPI: For threading an even number TPI,
use any numbered line on the thread dial (see the
example in Figure 94).
SCALE
1–8
&
1-2-3-4
Figure 94. Any numbered line on dial for
threading even TPI.
Note: For TPI divisible by 4, this rule still applies.
The Indicator Table on the lathe shows that lines
1–8 may be used, which means that lines 1–4 and
any of the half marks may be used.
3
2
4
1
Fractional TPI: For threading a fractional TPI with
a half number (4.5, 5.5, 6.5, 9.5), only use the 1
line on the thread dial (see the example in Figure
96).
3
TPI.
2
4
1
SCALE
1
Figure 96. 1 line on dial for threading fractional
Important: For cutting 4.75 TPI, proceed as
though cutting a metric thread and do not disengage the half nut until the threading operation is
complete. Stop the spindle at the end of each cut,
retract the cutting tool, and reverse the spindle to
return the cutting tool to the start of the thread.
Odd TPI: For threading an odd number TPI, use
any pair of opposite numbers or marks on the
thread dial (see the example in Figure 95).
3
SCALE
1, 3
2
4
1
Figure 95. 1 or 3 line on dial for threading odd
TPI.
Model G0791 (Mfd. Since 9/15)
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Page 66
SECTION 5: MILL OPERATIONS
Operation Overview
To reduce risk of injury and increase
longevity of machine, always start spindle
rotation with spindle speed dial set to lowest setting.
To complete a typical operation, the operator
does the following:
1. Examines workpiece to make sure it is suit-
able for cutting.
2. Securely clamps workpiece to table.
3. With machine disconnected from power,
installs correct cutting tool.
To reduce risk of eye or face injury from
flying chips, always wear approved safety
glasses and face shield when operating this
machine.
4. Adjusts headstock height above table.
5. Checks range of table or spindle movement
necessary for operation to make sure setup is
safe and correct.
6. Selects correct spindle speed and rotation
direction.
7. Puts on required safety glasses and face
shield.
8. Connects machine to power and turns it ON.
9. Uses downfeed controls or cross slide table
controls to perform cutting operation.
10. Turns machine OFF and waits for spindle to
completely stop before removing workpiece.
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Model G0791 (Mfd. Since 9/15)
Page 67
Removing
Compound Rest
The compound rest and tool post must be removed
before milling operations so the cross-slide table
can be used as the milling table.
Tool Needed Qty
Open-End Wrench 14 mm .................................. 1
Removing Compound Rest
1. Loosen both hex nuts shown in Figure 97,
then slide T-bolt out of first compound rest
slot.
Re-installing Compound Rest
1. Re-install one T-bolt, with flat washer and hex
nut, into rear T-slot, as shown in Figure 99.
x 1
Figure 99. T-Bolt installed in rear T-slot.
2. Align compound rest with cross slide table,
and insert T-bolt from Step 1 into rear slot of
compound rest.
x 2
Figure 97. Location of compound rest hex nuts
and flat washers.
2. Remove compound rest, then remove
second T-bolt from rear T-slot in cross-slide
table (see Figure 98).
Cross Slide
Table
T-Slots
With T-Bolts
Removed
3. Re-install second T-bolt with flat washer and
hex nut into T-slot and front slot of compound
rest, slide compound rest to desired position,
then tighten both hex nuts (see Figure 100).
Front Slot
T-Slot
Figure 100. Compound rest installed.
x 1
Figure 98. Compound rest and T-bolts removed.
Model G0791 (Mfd. Since 9/15)
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Page 68
Downfeed Controls
Identification
A
B
F
Figure 101. Downfeed controls.
E
D
Coarse Downfeed
Coarse downfeed is typically used for drilling
applications. Loosen the quill lock bolt, pull out
the down feed selector knob, then rotate either
of the coarse downfeed handles (see Figure
101) to lower the spindle. An internal coil spring
helps raise the spindle back to the top position
C
when you stop applying downward pressure on
the handle. Spindle travel is shown on the depth
scale, and is limited by the depth pointer when the
scale lock knob is secured.
Note: To maintain control of the upward spindle
travel and the rotating bit in your workpiece,
always continue holding the handle until the
spindle returns to the top position. Letting go of
the coarse downfeed handles when the spindle
is in the lowered position will cause the spindle to
retract too quickly and slam up into the headstock
or lift the workpiece and cause it to spin out of
control.
A. Quill Lock Bolt
B. Depth Scale Lock Knob
C. Coarse Downfeed Handles
D. Downfeed Selector Knob
E. Depth Pointer and Scale
F. Fine Downfeed Handwheel
The coarse downfeed hub features a graduated
dial that measures spindle movement in 0.02"
increments, with one full revolution equaling 2.40"
of spindle travel.
Fine Downfeed
Fine downfeed is typically used for milling applications, because the spindle only moves up or
down when the fine downfeed handwheel (see
Figure 101) is rotated (there is no automatic spindle return to the top position, as with the coarse
downfeed controls). This allows the spindle height
to be locked in place for precise Z-axis positioning
of a cutter or end-mill when milling a flat surface
across the face of a workpiece. In order to ensure
the milled surface remains flat, the spindle height
cannot move until the entire milling operation is
complete.
The fine downfeed graduated dial measures spindle movement in 0.002" increments, with one full
revolution equaling 0.092" of spindle travel.
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Model G0791 (Mfd. Since 9/15)
Page 69
Engaging Fine Downfeed Controls
In the following example, the fine downfeed
controls are used to mill 0.010" off a workpiece:
Tool Needed Qty
Open-End Wrench 13 mm .................................. 1
1. Loosen Z-axis lock bolts, use vertical travel
handwheel (see Figure 102 on this page) to
adjust cutting tool just above workpiece surface, then secure headstock with Z-axis lock
bolts.
2. Loosen quill lock bolt (see Figure 101 on
Page 66).
Headstock
Movement
The milling headstock travels up and down the
column (Z-axis) and tilts 90° left or right relative
to the table.
Tool Needed Qty
Open-End Wrench 13 mm .................................. 1
Raising/Lowering Headstock
1. Loosen two Z-axis lock bolts on right side of
headstock (see Figure 102).
3. Push downfeed selector knob (see Figure
101 on Page 66) all the way in to engage fine
downfeed handwheel.
4. Loosen depth scale lock knob.
5. Rotate fine downfeed handwheel clockwise
and lower cutting tool so it just touches
workpiece.
6. Move workpiece out of the way.
7. Using graduated dial to gauge spindle move-
ment, rotate fine downfeed handwheel clockwise 0.010".
8. Tighten quill lock bolt.
9. Turn mill/drill ON and perform cutting pass.
2. Use Z-axis handwheel shown in Figure 102
to adjust headstock height and relative position of cutting tool before cutting.
Note: Rotate the Z-axis handwheel clockwise
to raise the headstock, or counterclockwise
to lower it.
Vertical Travel
Handwheel
Z-Axis Lock
Bolts (1 of 2)
Figure 102. Mill Z-axis controls.
Model G0791 (Mfd. Since 9/15)
3. Re-tighten Z-axis lock bolts.
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Page 70
Tilting Headstock
Have another person support the headstock by
hand during Steps 2–3 to prevent headstock from
slipping out of control while tilting it.
These movements are controlled by the carriage handwheel and cross slide handwheel (see
Figure 105).
Tool Needed Qty
Wrench 17mm.................................................... 1
To tilt headstock:
1. DISCONNECT MACHINE FROM POWER!
2. With someone supporting headstock by hand,
loosen two tilt locking nuts on each side of
mill headstock (see Figure 103).
3. While viewing tilt scale (see Figure 103),
rotate headstock to required angle, then
retighten locking nuts to secure headstock.
Locking Nut
(1 of 2)
Tilt
Scale
Cross Slide
Table
Figure 105. Table travel controls.
Cross Slide
Handwheel
(Y-Axis)
Carriage
Handwheel
(X-Axis)
Carriage Handwheel (X-Axis)
Graduated Dial
Increments ................................. 0.010" (0.25mm)
One Full Revolution ..................0.670" (17.02mm)
Use the carriage handwheel to move the carriage
left or right along the bed. Adjust the position of
the graduated scale by holding the handwheel
with one hand and turning the dial with the other.
Figure 103. Location of tilt locking nut and tilt
scale.
Table Travel
The cross slide table travels in the X-axis (longitudinal), and the Y-axis (cross) directions, as
illustrated in Figure 104.
X-Axis or Longitudinal Travel (Left & Right)
Y-Axis or
Cross Travel
(In & Out)
Cross Slide Handwheel (Y-Axis)
Graduated Dial
Increments .................................0.002" (0.05mm)
One Full Revolution .......................0.2" (5.08mm)
Use this handwheel to move the cross slide table
toward or away from the tooling. The cross slide
handwheel is graduated to read diameter changes when turning a shaft. Divide the increments by
2 to determine how far the slide has travelled.
Figure 104. Cross slide travel directions.
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Page 71
Installing/Removing
Tooling
Installing Tooling
Tools Needed Qty
Wrench 10mm ................................................... 1
Spindle Locking Pin (Not Included) ................... 1
This machine features a spindle that accepts R-8
collets and arbors. It can also use MT#3 or MT#2
tooling with the included adapter sleeves.
The Model G0791 includes the following spindle
tools (see Figure 106):
A. B16 Drill Chuck w/R-8 Arbor. Refer to
Joining Drill Chuck & Arbor on Page 45.
B. R-8–MT#3 Spindle Sleeve. Used for MT#3
tools and will accommodate tools with a tang.
It also has a drift key slot for tool removal.
C. MT#3–MT#2 Spindle Sleeve. Used with the
R-8–MT#3 spindle sleeve for MT#2 tools.
Alignment Slot
A
To install tooling:
1. DISCONNECT MACHINE FROM POWER!
2. Verify drawbar is installed correctly (refer to
Page 24).
3. Align tool alignment slot (see Figure 106)
with pin inside spindle, then insert tooling into
spindle until it contacts drawbar.
4. Thread drawbar into tooling by hand until
snug (see Figure 107).
C
B
Figure 106. Drill chuck, arbor, and spindle
sleeves included with Model G0791.
Cutting tools are sharp and
can easily cause cutting
injuries. Always protect
your hands with leather
gloves or shop rags when
handling cutting tools.
Figure 107. Threading drawbar into tooling.
Model G0791 (Mfd. Since 9/15)
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Page 72
5. Set spindle speed to 250 RPM (see Setting
Spindle Speed on Page 51) to prevent spin-
dle rotation while tightening drawbar, then
use 10mm wrench to tighten drawbar.
—If necessary, you can insert a tool into hole
on side of spindle to provide additional
rotational resistance (see Figure 108).
Removing Tooling
Tools Needed Qty
Wrench 10mm ................................................... 1
Spindle Locking Pin (Not Included) ................... 1
Brass Head or Deadblow Hammer
(Not Included) .................................................... 1
To remove tooling:
Note: Do not overtighten drawbar.
Overtightening makes tool removal difficult
and may damage arbor and threads.
Tool Inserted
Into Spindle
Figure 108. Using tool to lock spindle while
tightening drawbar.
1. DISCONNECT MACHINE FROM POWER!
2. Set spindle speed to 250 RPM (see Setting
Spindle Speed on Page 51) to prevent spin-
dle rotation while tightening drawbar, then
tighten drawbar.
—If necessary, you can insert a tool into hole
on side of spindle to provide additional
rotational resistance (see Figure 108).
3. Unthread drawbar from tooling one full rotation.
Note: Do not fully unthread tooling from
drawbar or the drawbar and tool threads
could be damaged in the next step.
4. Tap top of drawbar with hammer to unseat
taper (see Figure 109).
-70 -
Figure 109. Example of tapping drawbar to
unseat tool taper.
5. Hold onto tooling with one hand and fully
unthread drawbar.
Model G0791 (Mfd. Since 9/15)
Page 73
Spindle Speed
Using the correct spindle speed is important for
safe and satisfactory results, as well as maximizing tool life.
To set the mill spindle speed for operation, you
will need to: 1) Determine the best spindle speed
for the cutting/drilling task, and 2) use the spindle
speed shift levers to obtain the spindle speed.
Determining Spindle Speed
Many variables affect the optimum spindle speed
to use for any given operation, but the two most
important are the recommended cutting speed
for the workpiece material and the diameter of
the cutting tool, as noted in the formula shown in
Figure 110.
Setting Spindle Speed
1. Set Mill FWD/REV switch to desired direction
for milling operations (see Figure 111).
Mill FWD/REV
Switch
Figure 111. Location of Mill FWD/REV switch.
2. Move spindle speed shift levers, according
to spindle speed chart (see Figure 112),
to select between 250, 530, 1100, or 2300
RPM. Figure 112 illustrates spindle speed
set at 250 RPM.
Figure 110. Spindle speed formula for mill/drills.
Cutting speed, typically defined in feet per minute
(FPM), is the speed at which the edge of a tool
moves across the material surface.
A recommended cutting speed is an ideal speed
for cutting a type of material in order to produce
the desired finish and optimize tool life.
The books Machinery’s Handbook or Machine
Shop Practice, and some internet sites, provide excellent recommendations for which cutting
speeds to use when calculating the spindle speed.
These sources also provide a wealth of additional
information about the variables that affect cutting
speed and they are a good educational resource.
Also, there are a large number of easy-to-use
spindle speed calculators that can be found on
the internet. These sources will help you take into
account the applicable variables in order to determine the best spindle speed for the operation.
Spindle
Spindle Speed
Shift Levers
250
530
Figure 112. Mill spindle speed controls set for
250 RPM.
Speed
Chart
1100
2300
Model G0791 (Mfd. Since 9/15)
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Page 74
ACCESSORIES
SECTION 6: ACCESSORIES
T10556—Taper Attachment Kit for G0791
This taper attachment provides precision outside
and inside tapers up to 12" without having to offset the tailstock. Can be used without disengaging the cross slide, allowing the taper attachment
to be functional at any time by simply tightening
the bed clamp bracket, and will not interfere with
other turning operations. This taper attachment
features scales at both ends, reading inches-oftaper per foot and angle of taper. An adjustment
knob with fine threads achieves precise control
when setting tapers.
T25250—58 pc. Clamping Kit 5/16"-18, 3/8"
T-Slot
Our Clamping Kits are among the best in the
world! All the blocks, bolts, nuts and hold-downs
are case hardened. Each clamping kit includes:
(24) studs (four studs each: 3", 4", 5", 6", 7", and
8" long), (6) step block pairs, (6) T-nuts, (6) flange
nuts, (4) coupling nuts, and (6) end hold-downs.
The Model T25250 set fits 3/8" T-slots and
includes 5/16"-18 studs. Racks can be bolted to
the wall or side of machine for easy access.
Figure 114. T25250 58 pc Clamping Kit 5/16"-
18, 3/8" T-Slot.
G5942—Extra Tool Holder For Quick Change
Tool Post
Set a variety of tool bits and drop in for a quick
change over.
Figure 113. T10556 Taper Attachment Kit for
G0791.
-72-
Figure 115. G5942 Extra Tool Holder For Quick
Change Tool Post.
Model G0791 (Mfd. Since 9/15)
Page 75
G1238 —15 pc. Precision 5-C Collets Set
Made from high grade collet steel and precision
ground to exacting tolerances. Complete 15 pc.
set. Includes: 1/8" thru 1" in 1/16" increments.
Figure 116. G1238 15 pc. Precision 5-C Collets
Set.
T10719 —Crown Savers for .17 to .45 Caliber
Barrels (10 Pk.)
T10720—Crown Savers for .50 Caliber Barrels
(3 Pk.)
With crown savers you never have to recrown
the barrel when installing muzzle brakes or doing
any job requiring a center in the end of the barrel
crown.
T24512—6-Pc. HSS Center Drill Set
HSS double-ended, 60° center drills are precision-ground. Set includes:
1
• 1 each of size #1, body diameter
3
diameter
⁄64", overall length 1 1⁄2"
• 2 each of size #2, body diameter
5
diameter
⁄64", overall length 1 7⁄8"
• 2 each of size #3, body diameter
7
diameter
⁄64", overall length 2"
• 1 each of size #4, body diameter
1
diameter
⁄8", overall length 2 1⁄8"
⁄8", drill
3
⁄16", drill
1
⁄4", drill
5
⁄16", drill
Figure 118. T24512 6-Piece Center Drill Set.
Figure 117. T10720 Crown Savers.
G7154 — Premium Milling Vise-5"
G7156 — Premium Milling Vise-4"
These swiveling milling vises feature perfectly
aligned, precision-ground jaws, robust clamping
screws, and easy-to-read 0°–360° scales.
Figure 119. Premium milling vises.
Model G0791 (Mfd. Since 9/15)
-73 -
Page 76
G1646—12 pc. Precision R-8 Collet Set
Made from the highest grade steel available for
collet manufactures, these collets are precision
ground to very close tolerances. Complete 12
1
piece set. Includes:
7
⁄8".
plus
⁄8" thru 3⁄4" in 1⁄16" increments
Figure 120. G1646 12 pc. Precision R-8 Collet
Set.
T10665—Adjustable Reamer Holder MT#3
This Pacific Tool and Gauge Adjustable Reamer
Holder secures a barrel chambering reamer in
the holder for free floating reamer movement. A
knurled wheel adjustment controls the amount of
tension, which also limits free-floating movement.
T10118—Tailstock Digital Readout
Here’s the slickest setup for managing the depth
of cut with your tailstock! Just set up, touch off and
zero out! You’re going to know the exact position
of the tool. Both the scale display and remote
display come with a 0.0005" (five ten-thousandths
of an inch) resolution, inch or millimeter display,
zero keys and ON/OFF keys. The scale has an 8"
range and its display features ABS or INC mode
as well as a Hold key. Both displays read independently of each other, too! You’ll be able to see your
1
depth at a glance with the large,
⁄2 " character
remote display. The 6' data cable is long enough
to mount the remote display in almost any convenient location. Tailstock adapter is not included,
but can be shop made to fit your lathe.
Figure 121. T10665 PTG Reamer Holder MT#3.
T10667—Bald Eagle Reamer Holder MT#3
This holder is designed to allow free movement
of a floating reamer in 3 directions: vertical, horizontal, and angular, as required for proper performance of any floating reamer.
Figure 122. T10667 Bald Eagle Reamer Holder
MT#3.
Figure 123. T10118 Tailstock Digital Readout.
T24798—Angle Plate Set, 2 pc.
Made of hardened, ground steel these angle
blocks provide accuracy within seconds, making
them a must have for any metal shop. One piece
3
is 3" x 3" x 4
other piece is 4" x 3
⁄8" with two 45° and 90° angles. The
3
⁄8" x 2" with 30°, 60°, and 90°
angles, making it perfect for setting your compound rest to 60° for threading.
Figure 124. Model T24798 Angle Plate Set, 2
pc.
-74 -
Model G0791 (Mfd. Since 9/15)
Page 77
T23962—ISO 68 Moly-D Way Oil, 5 gal.
T23963—ISO 32 Moly-D Machine Oil, 5 gal.
T26685—ISO 32 Moly-D Machine Oil, 1 gal.
T23964—Armor Plate with Moly-D MultiPurpose Grease, 14.5 oz. (NLGI#2 Equivalent)
Moly-D oils are some of the best we've found for
maintaining the critical components of machinery
because they tend to resist run-off and maintain
their lubricity under a variety of conditions—as
well as reduce chatter or slip. Buy in bulk and
save with 5-gallon quantities.
T23964
T23962 T23963 T26685
H8396—Chambering a Championship Match
Barrel DVD
Follow master gunsmith, Gordy Gritters, as he
gives step-by-step instructions in the highly precise area of chambering a rifle barrel worthy of
championship match shooting. Gordy Gritters is
a Benchrest Gunsmith who specializes in building 1000 yard rifles. He has built several rifles
that hold world records and have won National
Championships. He is extremely meticulous and
gives up many of his "secrets" on this video!
Figure 125. ISO 68 and ISO 32 machine oil and
multi-purpose grease.
T24803 —1" Dial Indicator & Small Magnetic
Base
Dial indicator has a range of 0–1" with an accuracy of within 0.001". Includes iGaging dial indicator, small magnetic base, and a protective case.
Figure 127. H8396 Chambering a Championship
Match Barrel DVD.
T25615—Milling for Home Machinists
Milling for Home Machinists is a project-based
course that provides a complete introduction to
milling and the use of the milling machine.
Figure 128. T25615 Milling for Home Machinists.
Figure 126. T24803 1" Dial Indicator & Small
Magnetic Base.
Model G0791 (Mfd. Since 9/15)
-75 -
Page 78
SECTION 7: MAINTENANCE
Schedule
Ongoing
To maintain a low risk of injury and proper
machine operation, if you ever observe any of the
items below, shut down the machine immediately
and fix the problem before continuing operations:
Daily, After Operations
• Press the Emergency Stop/RESET button (to
prevent accidental startup).
• Vacuum/clean all chips and swarf from bed,
slides.
• Wipe down all unpainted or machined sur-
faces with an oiled rag.
Semi-Annually
• Change the headstock oil (Page 78).
Annually
• Change the apron oil (Page 78).
• Lubricate end gears (Page 81).
• Check/level bedway (Page 25).
• Loose mounting bolts or fasteners.
• Worn, frayed, cracked, or damaged wires.
• Guards or covers removed.
• Emergency Stop/RESET button not working
correctly or not requiring you to reset it before
starting the machine again.
• Oil level not visible in the sight glasses.
• Damaged or malfunctioning components.
Daily, Before Operations
• Check/add headstock oil (Page 77).
• Add quick-change gearbox oil (Page 78).
• Check/add apron oil (Page 78).
• Lubricate the bedways (Page 79).
• Add oil to the ball oilers (Page 80).
• Clean/lubricate the leadscrew (Page 79).
• Check/retension V-belts (Page 89).
• Disengage the apron feed selection lever (to
prevent crashes upon startup).
• Ensure carriage lock bolt is loose.
Cleaning/Protecting
Because of its importance, we recommend that
the cleaning routine be planned into the workflow
schedule.
Typically, the easiest way to clean swarf from the
machine is to use a wet/dry shop vacuum that is
dedicated for this purpose. The small chips left
over after vacuuming can be wiped up with a
slightly oiled rag. Avoid using compressed air to
blow off chips, as this may drive them deeper into
the moving surfaces or cause sharp chips to fly
into your face or hands.
All unpainted and machined surfaces should be
wiped down daily to keep them rust free and in
top condition. This includes any surface that is
vulnerable to rust if left unprotected (especially
parts that are exposed to water-soluble cutting
fluid). Use way oil to prevent corrosion (see Page
75 for an offering from Grizzly).
-76 -
Model G0791 (Mfd. Since 9/15)
Page 79
Lubrication
Use the information in the charts below as a
daily guide for lubrication tasks. We recommend
using Grizzly Model T23962, T23963, or T23964
lubricants (see Pages 72 and 60) for most of the
lubrication tasks.
NOTICE
The recommended lubrication is based on
light-to-medium usage. Keeping in mind
that lubrication helps to protect the value
and operation of the lathe, these lubrication
tasks may need to be performed more frequently than recommended here, depending on usage.
Lubrication Frequency
Lubrication Task Frequency
Headstock Daily
Quick-Change Gearbox Daily
Apron Daily
Bedways Daily
Longitudinal Leadscrew Daily
Ball Oilers Daily
End Gears
Mill Leadscrew As Needed
Every 1000
Hours
Page
Ref.
Lubrication Amount & Type
Lubrication Task Oil Type Amount
Headstock ISO 32
Quick-Change Gearbox ISO 68
Apron ISO 68
Bedways ISO 68
Longitudinal Leadscrew ISO 68
Ball Oilers ISO 32
End Gears NLGI #2
Mill Leadscrew NLGI #2
3.5 Qt.
2 Pumps
0.5 Qt.
As
Needed
As
Needed
1–2
Squirts
Dab
As
Needed
77
78
78
79
79
80
81
81
Failure to follow reasonable lubrication
practices as instructed in this manual could
lead to premature failure of lathe components and will void the warranty.
Headstock
Oil Type .... Grizzly T23963 or ISO 32 Equivalent
Oil Amount .......................................... 3.5 Quarts
Check/Add Frequency ................................. Daily
Change Frequency ....................... Semi-Annually
The headstock gearing is lubricated by an oil bath
that distributes the lubricant with the motion of the
gears, much like an automotive manual transmission. Change the oil after the first 2 hours of use,
then semi-annually.
Checking Oil Level
The headstock reservoir has the proper amount of
oil when the oil level in the sight glass is approximately halfway. The oil sight glass is located
below the chuck, as shown in Figure 129.
Items Needed Qty
Hex Wrench 6mm .............................................. 1
Hex Wrench 8mm .............................................. 1
2-Gallon Catch Pan ........................................... 1
Pump-Type Oil Can w/Plastic Cone Tip ............ 1
Model G0791 (Mfd. Since 9/15)
Headstock
Oil Sight Glass
Figure 129. Location of headstock oil sight
glass.
-77-
Page 80
Adding Oil
The oil fill plug is located on top of the headstock,
as shown in Figure 130.
Quick-Change Gearbox
Oil Type .... Grizzly T23962 or ISO 68 Equivalent
Oil Amount ............................ 2 Pumps Each Port
Check/Add Frequency ................................. Daily
Fill Plug
Drain
Plug
Figure 130. Locations of headstock fill and drain
plugs.
To change headstock oil:
1. DISCONNECT MACHINE FROM POWER!
2. Remove end gear cover.
3. Remove V-belts so that oil does not get on
them, necessitating their replacement (refer
to the V-Belt Tension & Replacement on
Page 89 for detailed instructions).
4. Remove fill plug to allow oil to drain more
freely.
5. Place a funnel and a 2-gallon catch pan
under drain plug, then use 8mm hex wrench
to remove drain plug.
The quick-change gearbox uses a drip-type lubrication accessible through two ports on the right
side of the gearbox (see Figure 131).
Gearbox
Lubrication
Ports
Figure 131. Locations of gearbox oil ports.
Use a pump-type oil can to add two pumps to
each oil port, then wipe away any spilled oil.
Apron
Oil Type .... Grizzly T23962 or ISO 68 Equivalent
Oil Amount .......................................... 0.5 Quarts
Check/Add Frequency ................................. Daily
Change Frequency ................................ Annually
Checking Oil Level
The apron oil sight glass is on the front of the
apron, as shown in Figure 132. Maintain the oil
volume so that the level is approximately halfway
in the sight glass.
6. When headstock reservoir is empty, replace
drain plug and clean away any spilled oil.
7. Fill headstock reservoir until oil level is
approximately halfway in sight glass, then
replace fill plug.
8. Replace and retension V-belts, then secure
end-gear cover before reconnecting lathe to
power.
-78 -
Fill Plug
Sight
Glass
Figure 132. Location of apron oil sight glass.
Model G0791 (Mfd. Since 9/15)
Page 81
Changing Oil & Flushing Reservoir
Small metal particles may accumulate at the bottom of the reservoir with normal use. Therefore, to
keep the reservoir clean, drain and flush it at least
once a year.
Bedways
Oil Type .... Grizzly T23962 or ISO 68 Equivalent
Oil Amount ......................................... As Needed
Lubrication Frequency ................................. Daily
Place a catch pan under the apron drain plug
shown in Figure 133, remove the fill plug, then
use a 6mm hex wrench to remove the drain plug
and empty the reservoir.
Drain Plug
Figure 133. Location of apron drain plug.
Flush the reservoir by pouring a small amount of
clean oil into the fill hole and allowing it to drain
out the bottom. Replace the drain plug, add oil as
previously described, then re-install the fill plug.
Before lubricating the bedways (see Figure 134),
clean them with mineral spirits. Apply a thin coat
of oil along the length of the bedway. Move the
steady rest, carriage, and tailstock to access the
entire length of the bedways. If the lathe is in a
moist or dirty environment, increase the lubrication interval.
Bedways
Leadscrew
Figure 134. Bedways.
Longitudinal Leadscrew
Oil Type .... Grizzly T23962 or ISO 68 Equivalent
Oil Amount ......................................... As Needed
Lubrication Frequency ................................. Daily
Model G0791 (Mfd. Since 9/15)
Before lubricating the leadscrew (see Figure
134), clean it first with mineral spirits. A stiff brush
works well to help clean out the threads. Make
sure to move the carriage out of the way, so you
can clean the entire length of the leadscrew.
Apply a thin coat of oil along the length of the
leadscrew. Use a stiff brush to make sure the oil
is applied evenly and down into the threads.
Note: In some environments, abrasive material
can become caught in the leadscrew lubricant and
drawn into the half nut. In this case, lubricate the
leadscrew with a quality dry lubricant.
-79 -
Page 82
Ball Oilers
Oil Ty p e .... Grizzly T23963 or ISO 32 Equivalent
Oil Amount ......................................1 or 2 Squirts
Lubrication Frequency ................................. Daily
This lathe has 11 ball oilers, as shown in Figures
135 –138.
Ball Oilers
Proper lubrication of ball oilers is done with a
pump-type oil can fitted with a tip wide enough
to seal the ball oiler inlet. We do not recommend
using metal needle or lance tips, as they can push
the ball too far into the oiler, break the spring seat,
and lodge the ball in the oil galley.
Lubricate the ball oilers before and after machine
use, and more frequently under heavy use. When
lubricating ball oilers, first clean the outside surface to remove any dust or grime. Push the tip of
the oil can nozzle against the ball oiler to create
a hydraulic seal, then pump the oil can once or
twice. If you see sludge and contaminants coming
out of the lubrication area, keep pumping the oil
can until the oil runs clear. When finished, wipe
away any excess oil.
C
Figure 136. Carriage handwheel ball oiler.
D
A. Compound-rest leadscrew & slides
B. Saddle slides
C. Carriage handwheel
D. Tailstock ball oilers
E. Leadscrew end bearing
F. Feed rod end bearing
A
B
Figure 135. Saddle and slide ball oilers.
Figure 137. Tailstock ball oilers.
E
F
Figure 138. Leadscrew & feed rod ball oilers.
-80-
Model G0791 (Mfd. Since 9/15)
Page 83
End Gears
Grease ..... Grizzly T23964 or NLGI#2 Equivalent
Frequency ............... Annually or When Changing
5. Using a clean brush, apply a thin layer of
grease on gears. Make sure to get grease
between gear teeth, but do not fill teeth
valleys.
The end gears, shown in Figure 139, should
always have a thin coat of heavy grease to
minimize corrosion, noise, and wear. Wipe away
excess grease that could be thrown onto the
V-belts and reduce optimal power transmission
from the motor.
Lubrication
Port
Figure 139. End gears exposed for lubrication.
6. Install end gears and mesh them together
with an approximate 0.002"–0.004" backlash.
Once gears are meshed together, apply
small dab of grease between them where
they mesh together—this grease will be distributed when gears rotate and recoat any
areas scraped off during installation.
7. Re-install end gear cover before reconnecting lathe to power.
Mill Leadscrew
Lube Type . . Model T23964 or NLGI#2 Equivalent
Lube Amount ........................................Thin Coat
Lubrication Frequency ....................... As Needed
Before lubricating the mill leadscrew (see Figure
140), clean it first with mineral spirits. A stiff brush
works well to help clean out the threads. Make
sure to move the headstock of the way, so you
can clean the entire length of the leadscrew.
Handling & Care
Make sure to clean and lubricate any gears you
install or change. Be very careful during handling
and storage—the grease coating on the gears will
easily pickup dirt or debris, which can then spread
to the other gears and increase the rate of wear.
Make sure the end gear cover remains installed
whenever possible to keep the gears free of dust
or debris from the outside environment.
Lubricating
1. DISCONNECT MACHINE FROM POWER!
2. Remove end gear cover and all end gears
(see Figure 139).
3. Clean end gears thoroughly with mineral spir-
its to remove old grease. Use a small brush if
necessary to clean between teeth.
4. Clean shafts and wipe away any grease
splatters in vicinity and on inside of end gear
cover.
When dry, apply NLGI#2 grease to exposed
leadscrew threads. Move headstock through its
full range of motion several times to disperse
grease along full length of leadscrew.
Mill
Leadscrew
Figure 140. Location of mill leadscrew.
Model G0791 (Mfd. Since 9/15)
-81-
Page 84
Machine Storage
6. Place a few moisture absorbing desiccant
packs inside of electrical box.
To prevent the development of rust and corrosion,
the lathe must be properly prepared if it will be
stored for a long period of time. Doing this will
ensure the lathe remains in good condition for
later use.
Preparing Lathe for Storage
1. Run lathe and bring headstock and apron
reservoirs to operating temperature, then
drain and refill them with clean oil.
2. DISCONNECT MACHINE FROM POWER!
3. Thoroughly clean all unpainted, bare metal
surfaces, then apply a liberal coat of way
oil, heavy grease, or rust preventative. Take
care to ensure these surfaces are completely
covered but that rust preventative or grease
is kept off of painted surfaces.
4. Lubricate machine as outlined in Lubrication
section beginning on Page 77. Be sure to use
an oil can to purge all ball oilers and oil passages with fresh oil.
5. Loosen or remove V-belts so they do not
become stretched during storage period. (Be
sure to place a maintenance note near power
button as a reminder that the belts have been
loosened or removed.)
7. Cover lathe and place it in a dry area that is
out of direct sunlight and away from hazardous fumes, paint, solvents, or gas. Fumes
and sunlight can bleach or discolor paint.
8. Every few months, rotate by hand all geardriven components a few times in several
gear selections. This will keep the bearings,
bushings, gears, and shafts well lubricated
and protected from corrosion—especially
during the winter months.
Slide carriage, tailstock, and steady rest
down lathe bed to make sure that way spotting is not beginning to occur.
Bringing Lathe Out of Storage
1. Re-install V-belts and retension them (refer
to Page 89 for detailed instructions) if you
removed them for storage purposes.
2. Remove moisture absorbing desiccant packs
from electrical box.
3. Repeat Test Run and Spindle Break-In procedures, beginning on Page 28.
-82-
Model G0791 (Mfd. Since 9/15)
Page 85
SECTION 8: SERVICE
Troubleshooting
Motor & Electrical
Symptom Possible Cause Possible Solution
Machine does not
start or a circuit
breaker trips.
Motor stalls or is
underpowered.
Loud, repetitious
noise coming from
lathe at or near the
motor.
Motor overheats. 1. Motor overloaded. 1. Allow motor to cool; reduce load on motor.
Motor is loud when
cutting, or it bogs
down under load.
1. Power supply switched OFF or at fault.
2. Lathe spindle switch not engaged.
3. Emergency Stop\RESET button engaged
or at fault.
4. Thermal overload relay has tripped.
5. Wall fuse/circuit breaker is blown/tripped;
short in electrical system; start-up load too
high for circuit.
6. Fuse has blown in machine electrical box.
7. Contactor not getting energized/has burned
contacts.
8. Wiring is open/has high resistance.
9. Motor/plug wired incorrectly.
10. Mill FWD/REV switch at fault.
11. Start capacitor at fault.
12. Motor is at fault.
1. V-belt(s) slipping.
2. Run capacitor at fault.
3. Plug/receptacle at fault.
4. Gearbox at fault.
5. Contactor not energized/has poor contacts.
6. Motor bearings at fault.
7. Motor at fault.
1. Pulley set screws or keys are missing or
loose.
2. Motor fan is hitting the cover.
1. Excessive depth of cut or feed rate.
2. Spindle speed or feed rate wrong for
cutting operation.
3. Cutting tool is dull.
1. Ensure power supply is ON/has correct voltage.
2. Move spindle lever (Page 6) to engage switch.
3. Rotate button clockwise until it pops out to reset it
for operation; replace if not working properly.
4. Test/replace relay. If relay continues to trip, call tech
support for assistance.
5. Verify circuit is rated for machine amp load;
troubleshoot and repair cause of overload; replace
weak breaker; find/repair electrical short.
6. Replace fuse; determine if overload is due to heavy
operation; ensure power source has high enough
voltage and power cord is correctly sized.
7. Test for power on all legs and contactor operation.
Replace unit if faulty.
8. Check for broken wires or disconnected/corroded
connections, and repair/replace as necessary.
9. Correct motor/plug wiring connections (Pages 98
and 100).
10. Test/replace if necessary.
11. Test/replace if faulty.
12. Test/repair/replace.
1. Tension/replace V-belt(s) (Page 89); ensure pulleys
are aligned and free of oil/grease.
2. Test/repair/replace.
3. Test for good contacts/correct wiring.
4. Select appropriate gear ratio; replace broken or
slipping gears.
5. Test all legs for power/replace if faulty.
6. Test/repair/replace.
7. Test/repair/replace.
1. Inspect keys and set screws. Replace or tighten if
necessary.
2. Tighten fan, shim cover, or replace items.
1. Decrease depth of cut or feed rate.
2. Refer to feed/speed charts in Machinery's
Handbook or feed/speed calculator on the internet.
3. Sharpen or replace the cutting tool.
Model G0791 (Mfd. Since 9/15)
-83-
Page 86
Lathe
Symptom Possible Cause Possible Solution
Entire machine
vibrates upon
startup and while
running.
Bad surface finish. 1. Wrong spindle speed or feed rate.
Tapered tool difficult
to remove from
tailstock quill.
Cross slide,
compound rest, or
carriage feed has
sloppy operation.
Cross slide,
compound,
or carriage
handwheels hard to
move.
Cutting tool
or machine
components vibrate
excessively during
cutting.
Workpiece is
tapered.
Chuck jaws will
not move or do not
move easily.
Carriage will not
feed or is hard to
move.
Gear change levers
will not shift.
1. Workpiece is unbalanced.
2. Loose or damaged V-belt(s).
3. V-belt pulleys are not properly aligned.
4. Chuck or faceplate is unbalanced.
5. Change gears not aligned or no backlash.
6. Broken gear or bad bearing.
7. Workpiece is hitting stationary object.
8. Spindle bearings at fault.
2. Dull tooling or poor tool selection.
3. Tool height not at spindle centerline.
4. Too much play in gibs.
1. Quill not fully retracted into tailstock.
2. Contaminants not removed from taper
before inserting into quill.
1. Gibs out of adjustment.
2. Handwheel is loose or backlash is high.
3. Leadscrew mechanism worn.
1. Dovetail ways loaded with shavings, dust,
or grime.
2. Gib screws are too tight.
3. Backlash setting too tight.
4. Bedways are dry.
1. Tool holder not tight enough.
2. Cutting tool sticks too far out of tool holder;
lack of support.
3. Gibs are out of adjustment.
4. Dull cutting tool.
5. Incorrect spindle speed or feed rate.
1. Headstock and tailstock not properly
aligned with each other.
1. Chips lodged in jaws or scroll plate. 1. Remove jaws, clean and lubricate scroll plate, then
1. Gears not all engaged.
2. Half nut lever engaged.
3. Loose screw on feed handle.
4. Carriage lock is tightened down.
5. Chips have loaded up on bedways.
6. Bedways are dry and in need of lubrication.
7. Gibs are too tight.
8. Gears broken.
1. Gears not aligned inside headstock/quickchange gearbox.
1. Re-install workpiece; center with spindle bore.
2. Retension/replace V-belt(s) (see Page 89).
3. Align V-belt pulleys.
4. Rebalance chuck or faceplate; contact a local
machine shop for help.
5. Adjust change gears and establish backlash.
6. Replace broken gear or bearing.
7. Stop lathe and correct interference problem.
8. Reset spindle bearing preload (Page 91) or replace
worn spindle bearings.
1. Adjust for appropriate spindle speed and feed rate.
2. Sharpen tooling or select a better tool for operation.
3. Adjust tool height to spindle centerline (Page 41).
4. Tighten gibs (see Page 87).
1. Turn quill handwheel until it forces tool out of quill.
2. Clean taper and bore, then re-install tool.
1. Adjust gibs (see Page 87).
2. Tighten handwheel fasteners, adjust handwheel
backlash to a minimum (see Page 86).
3. Replace leadscrew mechanism.
1. Remove gibs, clean ways, lubricate, and re-adjust
gibs.
2. Loosen gib screw(s) slightly (see Page 87), and
lubricate bedways.
3. Slightly loosen backlash setting (see Page 86).
4. Lubricate bedways/ball oilers (Page 79).
1. Check for debris, clean, and retighten.
2. Re-install cutting tool so no more than
length is sticking out of tool holder.
3. Adjust gibs (see Page 87).
4. Replace or resharpen cutting tool.
5. Use the recommended spindle speed and feed rate.
1. Re-align tailstock to the headstock spindle
centerline (see Page 41).
replace jaws.
1. Adjust gear levers.
2. Disengage half nut lever.
3. Tighten.
4. Ensure carriage lock bolt is fully released.
5. Frequently clean away chips that load up during
turning operations.
6. Lubricate bedways/ball oilers.
7. Loosen gibs screw(s) slightly (see Page 87).
8. Replace gears.
1. Rotate spindle by hand with light pressure on the
lever until gear falls into place.
1
⁄3 of the total
-84-
Model G0791 (Mfd. Since 9/15)
Page 87
Mill
Symptom Possible Cause Possible Solution
Tool loose in spindle. 1. Tool is not fully drawn up into spindle taper.
2. Debris on tool or in spindle taper
3. Taking too big of a cut.
Breaking tools or
cutters.
Workpiece or tool
vibrates or chatters
during operation.
Table is hard to
move.
Headstock is hard to
raise.
Bad surface finish. 1. Spindle speed/feed rate is too fast.
Cutting results not
square.
Spindle overheats. 1. Mill/drill operated at high speeds for
Lack of power at
spindle.
Spindle does not
return to highest
position.
Mill FWD/REV
switch does not
work.
1. Spindle speed/feed rate is too fast.
2. Cutting tool is too small.
3. Cutting tool getting too hot.
4. Taking too big of a cut.
5. Spindle extended too far down.
1. Table locks not tight.
2. Workpiece not secure.
3. Spindle speed/feed rate is too fast.
4. Spindle extended too far down.
5. Quill lock lever not tight.
6. Gibs too loose in table
1. Table locks are tightened down.
2. Chips have loaded up on ways.
3. Ways are dry and need lubrication.
1. Headstock lock(s) or gib is at fault.
2. Headstock lead screw is binding
2. Dull or incorrect cutting tool.
3. Wrong rotation of cutting tool.
4. Workpiece not secure.
5. Spindle extended too far down.
1. Table travel is inconsistent. 1. Adjust gibs.
extended period.
1. Wrong voltage. 1. Correct voltage.
1. Poorly adjusted return spring.
2. Worn return spring.
1. Shorted/disconnected wiring. 1. Inspect circuit boards, wiring connections. Replace/
1. Tighten drawbar.
2. Clean tool and spindle taper.
3. Lessen depth of cut and allow chips to clear.
1. Set spindle speed correctly or use slower feed rate.
2. Use larger cutting tool and slower feed rate.
3. Use coolant or oil for appropriate application.
4. Lessen depth of cut and allow chips to clear.
5. Fully retract spindle and lower headstock. This
increases rigidity.
1. Tighten table locks.
2. Properly clamp workpiece on table or in vise.
3. Set spindle speed correctly or use slower feed rate.
4. Fully retract spindle and lower headstock. This
increases rigidity.
5. Tighten quill lock lever.
6. Tighten gibs.
1. Make sure table locks are fully released.
2. Frequently clean away chips that load up during
operations.
3. Lubricate ways.
1. Loosen/replace lock lever and adjust gib.
2. Clean and relubricate headstock leadscrew and
gears.
1. Set spindle speed correctly or use slower feed rate.
2. Sharpen cutting tool or select one that better suits
the operation.
3. Check for proper cutting tool rotation.
4. Properly clamp workpiece on table or in vise.
5. Fully retract spindle and lower headstock. This
increases rigidity.
1. Allow mill/drill to cool.
1. Increase return spring tension.
2. Replace return spring.
repair as necessary.
Model G0791 (Mfd. Since 9/15)
-85-
Page 88
Adjusting Backlash
Backlash is the amount of play in a leadscrew and
can be felt as the free play in a handwheel when
changing direction of rotation. The amount of the
backlash can be viewed on the handwheel graduated dial.
4. Rotate cross slide handwheel clockwise to
feed leadscrew nut out from under cross
slide, as shown in Figure 142.
Leadscrew Nut
When adjusting backlash, tighten the components
enough to remove backlash, but not so much that
the components bind the leadscrew, making it
hard to turn. Overtightening will cause excessive
wear to the sliding block and leadscrew.
Tools Needed Qty
Hex Wrench 2.5mm ........................................... 1
Hex Wrench 5mm .............................................. 1
Hex Wrench 6mm .............................................. 1
Punch Pin 2mm ................................................ 1
Cross Slide Backlash
1. DISCONNECT MACHINE FROM POWER!
2. Feed cross slide toward operator until it
reaches end of its travel.
3. Remove cap screw that secures cross slide
leadscrew nut (see Figure 141).
Note: You may need to rotate compound rest
(see Page 47) to expose cap screw.
Backlash
Adjustment
Cap Screw
Figure 142. Cross slide leadscrew nut.
5. Tighten backlash adjustment cap screw
shown in Figure 142 in small increments.
6. Hold leadscrew nut and test after each
adjustment by rotating handwheel back-andforth until backlash amount is approximately
0.002"–0.004".
7. Feed leadscrew nut back under cross slide
and replace cap screw removed in Step 2.
Compound Rest Backlash
1. Turn compound rest handwheel counter-
clockwise several turns.
Cap Screw Securing
Leadscrew Nut to
Cross Slide
Figure 141. Location of cap screw that secures
the leadscrew nut.
-86-
2. Loosen set screws on compound rest faceplate several turns (see Figure 143).
Faceplate
Set
Screws
Figure 143. Compound rest backlash
adjustments.
Model G0791 (Mfd. Since 9/15)
Page 89
3. Use punch pin to loosen faceplate and adjust
it until backlash is approximately 0.002"–
0.004", as indicated on graduated dial.
4. Secure setting with set screws.
Tools Needed Qty
Standard Screwdriver #2 ................................... 1
Hex Wrench 3mm .............................................. 1
Hex Wrench 6mm .............................................. 1
Wrench 10mm ................................................... 1
5. Repeat adjustments above if necessary.
Adjusting Gib
The goal of adjusting the gib screws is to remove
sloppiness or "play" from the ways without overadjusting them to the point where they become
stiff and difficult to move.
In general, loose gibs cause poor finishes and
tool chatter; however, over-tightened gibs cause
premature wear and make it difficult to turn the
handwheels.
The cross-slide and compound slide on this lathe
each use a long steel wedge called a gib that is
positioned between the component and its dovetailed-ways. At the end of each gib is a gib screw,
which moves and holds the gib. Depending upon
which direction the gib moves, the space between
the sliding ways increases or decreases to control
the rigidity of the cross slide and compound slide.
Make sure the bedways and leadscrew have
been cleaned and relubricated before beginning
any adjustments. Refer to Lubrication beginning on Page 77 for instructions and lubricant
specifications.
Cross Slide Gib
1. DISCONNECT MACHINE FROM POWER!
2. Loosen locking set screw shown in Figure
144.
Set
Gib Screw
(1 of 2)
Screw
Before adjusting the gibs, loosen the locks for
the device so that the gibs can freely slide during
adjustment, then lubricate the ways.
The gib adjustment process usually requires
some trial-and-error. Repeat the adjustment process as necessary until you find the best balance
between loose and stiff movement. Most machinists find that the ideal gib adjustment is one where
a small amount of drag or resistance is present,
yet the handwheels are still easy to move.
Figure 144. Cross slide gib components.
3. Adjust gib screws as follows:
— To increase slide tension, loosen rear gib
1
screw
1
⁄8 turn.
⁄8 turn, and tighten front gib screw
—To decrease slide tension, loosen front gib
1
screw
1
⁄8 turn.
⁄8 turn, and tighten rear gib screw
4. After each adjustment, use cross slide
handwheel to test cross slide movement.
5. Repeat Steps 3–4 until cross slide movement is acceptable.
Model G0791 (Mfd. Since 9/15)
-87-
Page 90
Compound Rest Gib
Figure 145 shows the gib location on the com-
pound rest. The compound rest gib adjusts in
the same manner and with the same tools as the
cross slide gib. However, in this case, to increase
or decrease tension, the gib adjustment screw
directions are reversed.
Set Screw
The saddle gib is located on the bottom of the
back edge of the slide (see Figure 147). This gib
is designed differently than the cross or compound
slide gibs. Instead of being a wedge-shaped plate,
it is a flat bar. The gib pressure is applied by four
set screws. Hex nuts secure these set screws in
place, so they will not loosen during operation.
Gib Screw
(1 of 2)
Figure 145. Compound rest gib components.
Saddle Gib
The saddle is supplied with a carriage lock on the
front right-hand side of the slide (see Figure 146).
This bolt locks the saddle in place for increased
rigidity when making face cuts. Before making
adjustments to the saddle gib, make sure that this
lock is loose by turning it counterclockwise one
full turn.
IMPORTANT: Do not loosen the carriage lock
more than a couple of turns or the components
inside will come apart. Re-installing these components is difficult and time consuming.
Carriage
Lock
Set Screws
Figure 147. Saddle gib components
(viewed from rear of saddle).
To adjust saddle slide gib:
1. DISCONNECT MACHINE FROM POWER!
2. Clean and lubricate lathe ways, slide, and
leadscrew (refer to Ball Oiler Lubrication on
Page 80 for instructions and lubricant specifi-
cations).
3. If carriage lock (see Figure 146) is tight,
loosen it two turns.
4. Loosen jam nuts on four set screws shown
in Figure 147, and adjust set screws same
amount as follows:
—To tighten carriage gib, tighten set screws.
Figure 146. Location of carriage lock.
-88-
—To loosen gib, loosen set screws.
5. Repeat adjustments as necessary until
adjustment is acceptable.
6. Hold set screws in place and tighten jam
nuts.
Model G0791 (Mfd. Since 9/15)
Page 91
Adjusting Half Nut
The half-nut mechanism can be adjusted if it
becomes loose from wear. The half nut is mounted
in the ways with a gib exerting pressure between
the components to reduce sloppy movement. The
half-nut gib is a flat bar-type gib, similar to the
saddle gib, and is tensioned with two set screws.
Tools Needed Qty
Hex Wrench 4mm .............................................. 1
Hex Wrench 5mm .............................................. 1
Open-End Wrench 13 mm .................................. 1
Tensioning/
Replacing V-Belt
After initial break in, the V-belts stretch slightly
and seat into the pulley. It is important to check
and adjust them to compensate for this initial
wear. Check the tension thereafter on a monthly
basis. If the belts become excessively worn or
damaged, replace them as a matched set.
Tool Needed Qty
Hex Wrench 17mm ............................................ 1
To adjust half nut:
1. DISCONNECT MACHINE FROM POWER!
2. Disengage half nut and remove thread dial.
3. Loosen hex nuts on set screws shown in
Figure 148.
Half Nut
Set
Screws
Figure 148. Half nut gib set screws.
Tensioning V-Belts
1. DISCONNECT MACHINE FROM POWER!
2. Remove end gear cover.
3. Loosen motor mount hex bolts (see Figure
149).
Note: It may be more convenient to access
the motor mount hex nuts if you first remove
the rear splash guard.
4. Tighten each set screw approximately
turn, then retighten the hex nuts without moving the set screws.
5. Move carriage handwheel until half nut can
fully close, then open/close half nut several
times and notice how it feels. The half nut is
correctly adjusted when you feel a slight drag
while opening and closing it. It should not feel
too stiff or too loose.
6. Repeat Steps 3–5, if necessary, until you
are satisfied with half nut adjustment, then
re-install thread dial.
Model G0791 (Mfd. Since 9/15)
1
⁄8 of a
Figure 149. Locations of motor mount hex bolts.
4. Push down on the motor and re-tighten the
mounting hex bolts.
-89-
Page 92
5. Check belt tension: Each belt is correctly
tensioned when there is approximately
deflection when it is pushed with moderate
pressure, as shown in Figure 150.
1
⁄4"
Figure 150. Correct timing-belt deflection.
1
⁄4"
Installing/Removing
Gap Insert
This lathe is equipped with a removable gap
insert that will allow for turning large diameter
workpieces. The gap was seated, preloaded, and
then ground for precise bedway mating and alignment at the factory.
Removing the gap can cause the lathe insert to
slightly spring out of shape. When re-installed,
there is no guarantee that original alignment and
flush mating will be the same. For this reason,
removing the gap is considered a permanent
alteration to the lathe, even if it is later re-installed.
—If there is more than 1⁄4" deflection when
each belt is pushed with moderate pressure, loosen the motor mount bolts, lower
the motor, adjust belt tension as required,
then tighten the bolts.
6. Secure end gear cover.
Replacing V-Belts
1. DISCONNECT MACHINE FROM POWER!
2. Remove end gear cover.
3. Loosen motor mount bolts (see Figure 149
on the previous page), slide motor up, and
remove V-belts.
Note: It may be more convenient to access
the motor mount bolts if you first remove the
rear splash guard.
4. Install new V-belts as a matched set so they
equally share the load.
5. Tension belts (refer to Tensioning/Replacing
V-Belt on the previous page.)
Tools Needed Qty
Open-End Wrench 14mm .................................. 1
Hex Wrench 8mm .............................................. 1
Heavy Dead Blow Hammer ............................... 1
Miscellaneous C-Clamps ................ As Required
Wooden Blocks ............................... As Required
Removing Gap Insert
1. DISCONNECT MACHINE FROM POWER!
2. Remove four cap screws that secure gap to
bed (see Figure 151).
Dowel Pin
& Jack Nut
(1 of 2)
Preload
Cap Screw
Cap
Screws
(2 of 4)
Figure 151. Gap retaining fasteners.
6. Secure end gear cover.
-90-
3. Tighten dowel pin jack nuts (see Figure 151)
to draw pins from gap.
Model G0791 (Mfd. Since 9/15)
Page 93
4. Loosen preload cap screw (see Figure 151)
a few turns until it no longer contacts headstock.
5. Tap outside of gap insert with dead blow
hammer to loosen it, and, with help of another
person, remove gap insert.
Re-Installing Gap Insert
1. Clean all mating surfaces completely with
mineral spirits. Inspect and remove any
burrs. ALL MATING SURFACES MUST BE
ABSOLUTELY CLEAN!
2. Lightly oil a lint-free cloth with way oil, and
rub a thin film into pores of freshly cleaned
gap surfaces. Next, place insert in position on
lathe bed.
Adjusting Spindle
Bearing Preload
This lathe is shipped from the factory with the
spindle bearing preload properly adjusted. If the
spindle ever develops a bit of end-play and the
workpiece finish suffers, you can adjust the bearing preload to remove the end-play and improve
the workpiece finish.
Adjusting the bearing preload requires using a
spanner wrench or a punch and hammer. You
can either purchase the spanner wrench at a tool
store or fabricate one, using the diagram shown
in Figure 152.
3. Back off threaded dowel pin jack nuts until
they are flush with end of pins, then drop pins
into pin holes in gap.
4. Jostle gap closer to its final alignment until
pins seat naturally.
5. Install and lightly snug four cap screws in
an order that will draw closer into alignment.
Using blocks of wood and clamps to get
mating surfaces into alignment can also be
helpful.
6. When alignment and flush mating is acceptable, tighten four cap screws in a pattern that
will maintain or improve alignment.
7. Wait 24 hours, and check for quality of mating. If unacceptable, use clamps and blocks
of wood, and loosen and tighten appropriate
cap screws to draw-in and release certain
areas of gap to achieve required alignment.
8. When satisfied with alignment, tap dowel pins
rest of way into gap until they are in a fully
seated position, and thread jack nuts down
until they just contact gap.
Fabricate from CRS
or HRS bar stock
"
9
16
⁄
1
Radius
Fabricate pin to 7⁄32" D x 1⁄4" L and weld.
Figure 152. Spanner wrench diagram.
Tools Needed Qty
Spanner Wrench 80–90mm Hook-Type ............ 1
Chuck Key ......................................................... 1
Dead Blow Hammer .......................................... 1
Piece of Scrap Wood......................................... 1
Dial Indicator ..................................................... 1
Hex Wrench 6mm .............................................. 1
12"
Adjusting Preload
1. Run lathe for 20 minutes on high speed to
bring lathe to a normal temperature.
2. DISCONNECT MACHINE FROM POWER!
9. Tighten preload cap screw until it contacts
headstock and resistance can be felt, then
tighten it an additional
Model G0791 (Mfd. Since 9/15)
3
⁄4-turn.
-91-
Page 94
3. Remove chuck, then shift spindle to neutral
by positioning alpha spindle speed lever
between C and B and numeric spindle speed
lever between the
I and II, as shown in
Figure 153.
Alpha
Lever
Set between
B & C
I
C
I
I
B
A
I
I
I
Numeric
Lever
Set between
I & II
Figure 153. Spindle speed levers set to neutral.
4. Remove end gear cover, then remove the
outboard spindle cover (see Figure 154).
Outboard
Spindle
Cover
7. Loosen inner spanner nut one turn.
Note: You may have to tap on the outboard
end of the spindle as explained in Step 8, to
help unload the spindle and break the spanner nut loose.
8. Place wooden block over outboard end of
spindle, tap it a few times with small sledge
or heavy dead blow hammer (see Figure
156). Your goal is to slide spindle forward
just enough to introduce spindle end-play that
you can feel by hand.
Figure 154. Outboard spindle cover.
5. Place chuck key in cam-lock socket and keep
spindle from rotating.
6. Using a spanner wrench, or hammer and
punch, loosen outer spanner nut (see
Figure 155) and remove it.
Spanner
Wrench
Outer Spanner Nut
Figure 155. Loosening outer spanner nut.
Figure 156. Introducing detectable end-play.
9. Place dial indicator on cross slide and move
carriage toward headstock until contact point
of indicator touches spindle face, as shown in
Figure 157.
Figure 157. Dial indicator setup.
10. Move carriage an additional 0.100" toward
headstock.
-92-
Model G0791 (Mfd. Since 9/15)
Page 95
11. Insert chuck key into a cam socket to prevent
spindle from turning, then tighten inner spanner nut until dial indicator needle just stops
moving (see Figure 158).
Figure 158. Adjusting spindle bearings.
Note: For convenience and accuracy, we
recommend having another person watch the
dial while you tighten the inner spanner nut.
While tightening the inner spanner nut,
rock the spindle back and forth slightly with
the chuck key to make sure the spindle
tapered roller bearings seat properly in their
races.
When the dial indicator needle stops mov-
ing, there will be no spindle end-play and no
bearing preload. It is important that you find
this point without tightening the spanner nut
too much and inadvertently preloading the
spindle bearings.
12. Tighten spanner nut an additional 1⁄16" along
its circumference. See Figure 159 for example of this measurement.
1
⁄16" Travel
Figure 159. Final spanner nut rotation.
13. Without allowing inner spanner nut to tighten
any further, install and tighten outer spanner
nut against the inner nut.
Do not overtighten outer spanner nut because
additional preload can force bearings even
tighter against races in headstock and cause
headstock to compress, or crack, or cause
bearing failure.
Confirming Bearing Preload
1. Re-attach removed lathe components and
prepare it for operation.
2. Install chuck and tighten jaws.
3. Set spindle speed to highest setting.
If you think you have gone past the zero end-
play point, unload the bearings by repeating
Steps 7–8, then retighten the inner spanner
nut until it has reached the zero end play
position.
Model G0791 (Mfd. Since 9/15)
4. Connect lathe to power and lathe spindle ON.
5. Let lathe run for 20 minutes, periodically shut-
ting it down a few times and checking spindle
nose temperature (refer to next step).
6. Turn spindle OFF, disconnect lathe from
power, and check temperature of spindle.
—If spindle nose is slightly warm to touch,
you have correct bearing preload.
—If spindle nose is too hot to touch, preload
is too tight and you must repeat bearing preload adjustment procedure. When
repeating procedure, rotate inner spanner
nut a little less during Step 12 in preceding
instructions.
-93-
Page 96
machine
SECTION 9: WIRING
Wiring Safety Instructions
-94-
Model G0791 (Mfd. Since 9/15)
Page 97
Wiring Overview
Electrical Panel
Lathe Motor
Control Panel
Spindle Switch
(Inside)
Work Lamp
Mill Motor
To Work Lamp
(Page 99)
To Control Panel
(Page 100)
To Spindle Switch
(Page 100)
To Electrical
Cabinet
(Page 96)
Hot
220
VAC
Hot
Ground
To Mill Motor
(Page 99)
To Lathe Motor
(Page 98)
G
6-15 Plug
(As Recommended)
Model G0791 (Mfd. Since 9/15)
READ ELECTRICAL SAFETY
ON PAGE 94!
-95-
Page 98
Ground
NO
NC
2T1
6T3
4T2
STOP RESET
95
98
97
FR1
96
11
13
A
6
Relay
2A
110V
110V
2A
5A
24V
24V
5A
NO
NC
2T1
6T3
4T2
STOP
Test
Test
RESET
95
98
97
FR2
5
6
A
4
96
Relay
1L1 3L2 5L3
JRS4-09/25d
Tianshui
Tianshui
1L1 3L2 5L3
JRS4-09/25d
26
30 31 32 33 E
25 24 23 22 21 20
TC
20-21 = 110V
20-22 = 220V
20-23 = 230V
20-24 = 240V
20-25 = 380V
20-26 = 400V
Transformer
MTE JBK5-100VATH
WUXI NO.5 MACHINE TOOL
13NO
JZC3 40d
33NO 43NO23NO
14NO 34NO 44NO24NO
KA0
A2
A1
A2
Contactor
KA0
A1
A2
A2
F3 11d
62NC
61NC
54NO
53NO
KA0
A1
A2
A2
F3 11d
62NC
61NC
54NO
53NO
KA0
A1
A2
A2
F3 11d
62NC
61NC
54NO
53NO
1L1 5L3 21NC3L2 1L1 5L3 21NC3L2 1L1 5L3 21NC3L2
1L1 5L3 21NC3L2
2T1 6T3 22NC4T2 2T1 6T3 22NC4T2 2T1 6T3 22NC4T2 2T1 6T3 22NC4T2
KA0
A1
A2
A2
19
19
20
20
Z1U2
1U1 1U2
Z1U2
8
8
5
19
19
5
5
L
N
U1
U1
NL
Z2
Z2
5
L
L
L
U2
U2
Z1
Z1
PE
PE
PE
PE
3
3
2
2 2
10
0
0
0
0
0
667
7
121213
13
1
1
1
0 0
11
11
11
11
1U1 1U2
U2
U2
1Z1
Z1
Z1
1Z1
Z2
Z2
L
N
N
N
N
N
L
L L
L
L L
L
L
L
N
N
N
14
15
15
14
10
10
9
9
L
L
L
12
13
7
6
5
42 31
PE PE
N
N
0
18
18
1
GSC11801
GSC11801
GSC11801
Tianshui
Tianshui
TianshuiTianshui
120V
KM3 KM4 KM1 KM2
120V 120V 120V 120V
Tianshui
GSC11801
F3 11d
62NC
61NC
54NO
53NO
21
21
8
8
L
N
U1
Electrical Cabinet Wiring Diagram
-96-
To
Mill Motor
Page 99
READ ELECTRICAL SAFETY
To
Work Lamp
Page 99
ON PAGE 94!
Lathe Motor
Page 95
To
To
Power Connection
Page 95
To
Control Panel
Page 100
Model G0791 (Mfd. Since 9/15)
To
Spindle Switch
Page 100
Page 99
Electrical Cabinet Wiring
Model G0791 (Mfd. Since 9/15)
Figure 160. Electrical cabinet wiring.
READ ELECTRICAL SAFETY
ON PAGE 94!
-97-
Page 100
Lathe Motor Wiring Diagram
To Electrical
Cabinet
Page 96
Motor 220V
Run
Capacitor
20MFD
450VAC
U2
U1
PE
Ground
Z1
Z2W2
U1
U2
V1V2Z1W1
Start
Capacitor
150MFD
250VAC
-98-
READ ELECTRICAL SAFETY
ON PAGE 94!
Figure 161. Lathe motor wiring.
Model G0791 (Mfd. Since 9/15)
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