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MODEL H7789
MORTISING KIT
INSTRUCTION SHEET
For questions or help with this product contact Tech Support at (570) 546-9663 or techsupport@grizzly.com
Introduction
The Model H7789 Mortising Kit features a quick
and easy way to produce mortises with your drill
press. The kit supplies everything you need to
mount the kit and produce mortises.
Fits drill presses with the following quill flange/
collar diameters: 2.95" (75mm), 2.60" (66mm),
2.36" (60mm), 2.17" (55mm), 2.00" (50mm), 1.89"
(48mm), 1.57" (40mm).
Note: Not intended to be used with small or "baby"
type drill presses.
Inventory
A. Cone ........................................................... 1
B. Fence Assembly ......................................... 1
C. Alignment Tool ........................................... 1
D. Mortising Chisels ........................................ 4
E. T-Nuts M6-1 ............................................... 4
F. Mounting Sleeves:
#1 Sleeve 2.95" OD x 2.60" (66mm) ID ...... 1
#2 Sleeve 2.60" OD x 2.36" (60mm) ID ..... 1
#3 Sleeve 2.36" OD x 2.17" (55mm) ID ...... 1
G. Mounting Bushings:
"A" Bushing 2.60" OD x 1.57" (40mm) ID ... 1
"B" Bushing 2.60" OD x 1.89" (48mm) ID ... 1
"C" Bushing 2.60" OD x 2.00" (51mm) ID ... 1
H. Hold Down Rods ........................................ 2
I. Hold Down .................................................. 1
J. Adjustable Handle M6-1 X 25 .................... 2
K. Fence Rod .................................................. 1
A
C
B
J
D
H
H7789 inventory components.
H7789 installed on a drill press.
COPYRIGHT © OCTOBER, 2005 BY GRIZZLY INDUSTRIAL, INC. REVISED MARCH, 2016 (MN)
WARNING: NO PORTION OF THIS MANUAL MAY BE REPRODUCED IN ANY SHAPE
OR FORM WITHOUT THE WRITTEN APPROVAL OF GRIZZLY INDUSTRIAL, INC.
#DD7686 PRINTED IN CHINA
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Mounting Cone
To reduce risk of shock or
accidental startup, always
disconnect machine from
1. DISCONNECT DRILL PRESS FROM
POWER!
power before adjustments,
maintenance, or service.
4. Use table below to determine required com-
ponents for installing cone on your drill press.
Fitting Size Use
2.95" (75mm) Direct Fit, No Bushings/Sleeves Needed
2.60" (66mm) #1 Sleeve
2.36" (60mm) #1 Sleeve, #2 Sleeve
2.17" (55mm) #1 Sleeve, #2 Sleeve, #3 Sleeve
2.00" (50mm) #1 Sleeve, "C" Bushing
1.89" (48mm) #1 Sleeve, "B" Bushing
1.57" (40mm) #1 Sleeve, "A" Bushing
2. Secure small end of alignment tool in drill
chuck.
3. Measure quill flange and quill body on your
drill press to determine which one is closest
to the fitting sizes listed below.
Fitting Size
• 2.95" (75mm)
• 2.60" (66mm)
• 2.36" (60mm)
• 2.17" (55mm)
• 2.00" (50mm)
• 1.89" (48mm)
• 1.57" (40mm)
Quill Body
Quill Flange
5. Slide cone over alignment tool and quill
mounting surface. Tighten adjustable handle
to secure cone to quill.
Bushing
Adjustable
Handle
Knob
DIRECT SLEEVE
Sleeve
SLEEVE & BUSHING
6. Loosen drill chuck and remove alignment
tool.
Mounting Fence
1. Position fence on top of drill press table and
align holes on ends with slots in table.
2. Secure fence in place using adjustable handles and appropriate T-nuts for your table.
Note: If the quill flange or quill body do not
match the fitting sizes shown, then this kit will
not properly mount to your drill press with the
components included.
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H7789 Mortising Kit (Mfd. 10/15)
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Making a Mortise
Proper alignment of the workpiece and chisel is
essential to making good mortise and tenon joints.
The instructions below describe one method of
creating square joints with an evenly spaced mortise. Place a spoil board on top of the drill press
table if a through-mortise is to be made.
1. Install chisel into cone, rotate it so opening
is positioned toward operator, and secure it
with the knob.
2. Secure drill bit into drill chuck. Slide the drill
bit into the chisel as far as it will go and then
allow it to drop back down
not done, wood chips generated by the cutting action will have no place to go, resulting
in excessive heat and damage to the tool.
1
⁄32" - 1⁄16". If this is
6. Set the speed of the drill press between 900
and 1200 RPM.
7. Carefully inspect the alignment. When you
are satisfied that the setup is worthy of being
tested, replace the workpiece with a scrap
piece of lumber that is the same size. Attach
the hold down bracket and rod(s), then make
a cut.
8. Watch the chips coming out of the slot on the
shank of the chisel. If you don't see chips, or
there is a lot of smoke, raise the chisel, turn
off the drill press and lower the drill in the
chisel. If burning still occurs, lower the drill
press speed. Some burning may occur with
certain species of wood regardless of the settings, but you should see wood chips while
cutting mortises with this tool.
3. Measure the surface of the workpiece that is
to have the mortise. Subtract the size of the
mortise chisel and divide this number in half.
Workpiece = .75"
Chisel = -.375"
.375" ÷ 2 = .1875"
4. Mark the workpiece where you want the mortise and clamp it to the fence.
5. Loosen the adjustable handles on the fence.
Lower the chisel with the spider handles on
the drill press and make adjustments to the
fence until the marks on the workpiece are
aligned with the chisel as shown in the figure
below. Tighten the adjustable handles. If
the fence cannot be adjusted close enough,
adjust the table on the drill press until the
chisel and marks are aligned.
9. Check the placement of the cut and make
any adjustments to the setup before cutting
a valuable workpiece.
Cut Sequence
Cutting mortises that are wider than the chisel
must be done in proper sequence for best results.
Below is a diagram on one possible sequence
that will produce good results.
4
2
3
1
Aligning the chisel and marks.
H7789 Mortising Kit (Mfd. 10/15)
Staggered cut sequence.
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H7789 Parts Breakdown and List
Please Note: We do our best to stock replacement parts whenever possible, but we cannot guarantee that all parts shown here
are available for purchase. Call (800) 523-4777 or visit our online parts store at www.grizzly.com to check for availability.
4
5
6
3
2
1
7
8
16V2
17V2
20V2
21V2
23
15
10
18
9
11
12
13
14
19
22
REF PART # DESCRIPTION REF PART # DESCRIPTION
1 PH7789001 BUSHING PAIR 2.6" X 1.57" 13 PH7789013 MORTISING CHISEL 3/8"
2 PH7789002 BUSHING PAIR 2.6" X 1.88" 14 PH7789014 MORTISING CHISEL 1/2"
3 PH7789003 BUSHING PAIR 2.6" X 2.00" 15 PH7789015 HOLD DOWN
4 PH7789004 SLEEVE 2.366" X 2.17" 16V2 PH7789016V2 ADJUSTABLE HANDLE M6-1 X 25 V2.10.15
5 PH7789005 SLEEVE 2.6" X 2.366" 17V2 PH7789017V2 FLAT WASHER 6MM
6 PH7789006 SLEEVE 2.945" X 2.6" 18 PH7789018 ROD
7 PH7789007 ADJUSTABLE HANDLE 19 PH7789019 FENCE
8 PH7789008 CONE 20V2 PH7789020V2 T-NUT (SMALL) M6-1
9 PH7789009 KNOB 21V2 PH7789021V2 T-NUT (LARGE) M6-1
10 PH7789010 SQUARE HD BOLT 5/16"-18 X 2" 22 PH7789022 HOLD DOWN ROD
11 PH7789011 MORTISING CHISEL 1/4" 23 PH7789023 ALIGNMENT TOOL
12 PH7789012 MORTISING CHISEL 5/16"
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H7789 Mortising Kit (Mfd. 10/15)
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