SLIMLINE BENCH GRINDER
MODEL H4378/H4379
INSTRUCTION MANUAL
COPYRIGHT © APRIL, 2002 BY GRIZZLY INDUSTRIAL, INC.
WARNING: NO PORTION OF THIS MANUAL MAY BE REPRODUCED IN ANY SHAPE
OR FORM WITHOUT THE WRITTEN APPROVAL OF GRIZZLY INDUSTRIAL, INC.
PRINTED IN CHINA.
ONLINE MANUAL DISCLAIMER
THE INFORMATION IN THIS MANUAL REPRESENTS THE CONFIGURATION OF THE MACHINE AS IT IS CURRENTLY BEING SHIPPED. THE
MACHINE CONFIGURATION CAN CHANGE AS PRODUCT IMPROVEMENTS ARE INCORPORATED. IF YOU OWN AN EARLIER VERSION OF THE
MACHINE, THIS MANUAL MAY NOT EXACTLY DEPICT YOUR MACHINE. CONTACT CUSTOMER SERVICE IF YOU HAVE ANY QUESTIONS
ABOUT DIFFERENCES. PREVIOUS VERSIONS ARE NOT AVAILABLE ONLINE.
Model H4378
Model H4379
WARNING
Some dust created by power sanding, sawing, grinding, drilling, and other construction activities contains
chemicals known to the State of California to cause
cancer, birth defects or other reproductive harm. Some
examples of these chemicals are:
• Lead from lead-based paints.
• Crystalline silica from bricks, cement, and other
masonry products.
• Arsenic and chromium from chemically treated
lumber.
Your risk from these exposures varies, depending on
how often you do this type of work. To reduce your
exposure to these chemicals: work in a well ventilated
area, and work with approved safety equipment, such
as those dust masks that are specially designed to filter out microscopic particles.
Table Of Contents
PAGE
1. SAFETY
SAFETY RULES FOR POWER TOOLS ..........................................................2-3
ADDITIONAL SAFETY INSTRUCTIONS FOR GRINDERS ................................4
2. CIRCUIT REQUIREMENTS
110V OPERATION ..............................................................................................5
EXTENSION CORDS ..........................................................................................5
GROUNDING ......................................................................................................5
3. INTRODUCTION
COMMENTARY....................................................................................................6
4. ASSEMBLY
UNPACKING ........................................................................................................7
PIECE INVENTORY ............................................................................................7
MOUNTING ..........................................................................................................8
TOOL RESTS ......................................................................................................8
EYE SHIELDS......................................................................................................8
5. OPERATIONS
TEST RUN............................................................................................................9
SAFE GRINDING ..............................................................................................10
WHEEL CARE....................................................................................................10
WHEEL SELECTION ........................................................................................11
WHEEL INSPECTION........................................................................................12
WHEEL MOUNTING ..........................................................................................13
6. MAINTENANCE
GENERAL ..........................................................................................................14
LUBRICATION ..................................................................................................14
GRINDING WHEELS ........................................................................................14
MAINTENANCE NOTES....................................................................................15
7. CLOSURE................................................................................................................16
TROUBLESHOOTING ......................................................................................................17
MACHINE DATA ..........................................................................................................18-19
PARTS BREAKDOWN AND PARTS LIST..................................................................20-21
WARRANTY AND RETURNS ..........................................................................................22
-2- H4378/H4379 Slimline Bench Grinder
SECTION 1: SAFETY
For Your Own Safety Read Instruction
Manual Before Operating This Equipment
Indicates an imminently hazardous situation which, if not avoided,
WILL result in death or serious injury.
Indicates a potentially hazardous situation which, if not avoided,
COULD result in death or serious injury.
Indicates a potentially hazardous situation which, if not avoided,
MAY result in minor or moderate injury. It may also be used to alert
against unsafe practices.
This symbol is used to alert the user to useful information about
proper operation of the equipment.
The purpose of safety symbols is to attract your attention to possible hazardous conditions. This
manual uses a series of symbols and signal words which are intended to convey the level of
importance of the safety messages. The progression of symbols is described below. Remember
that safety messages by themselves do not eliminate danger and are not a substitute for proper
accident prevention measures.
NOTICE
Safety Instructions For Power Tools
5. KEEP CHILDREN AND VISITORS
AWAY. All children and visitors should be
kept at a safe distance from work area.
6. MAKE WORKSHOP CHILD PROOF with
padlocks, master switches, or by removing
starter keys.
7. DO NOT FORCE TOOL. It will do the job
better and safer at the rate for which it was
designed.
8. USE RIGHT TOOL. Do not force tool or
attachment to do a job for which it was not
designed.
1. KEEP GUARDS IN PLACE and in working
order.
2. REMOVE ADJUSTING KEYS AND
WRENCHES. Form habit of checking to
see that keys and adjusting wrenches are
removed from tool before turning on.
3. KEEP WORK AREA CLEAN. Cluttered
areas and benches invite accidents.
4. DO NOT USE IN DANGEROUS ENVIRONMENT. Do not use power tools in
damp or wet locations, or where any flammable or noxious fumes may exist. Keep
work area well lighted.
H4378/H4379 Slimline Bench Grinder -3-
9. USE PROPER EXTENSION CORD. Make
sure your extension cord is in good condition. Conductor size should be in accordance with the chart below. The amperage
rating should be listed on the motor or tool
nameplate. An undersized cord will cause
a drop in line voltage resulting in loss of
power and overheating. Your extension
cord must also contain a ground wire and
plug pin. Always repair or replace extension cords if they become damaged.
Minimum Gauge for Extension Cords
10. WEAR PROPER APPAREL. Do not wear
loose clothing, gloves, neckties, rings,
bracelets, or other jewelry which may get
caught in moving parts. Non-slip footwear
is recommended. Wear protective hair covering to contain long hair.
11. ALWAYS USE SAFETY GLASSES. Also
use face or dust mask if cutting operation is
dusty. Everyday eyeglasses only have impact
resistant lenses, they are NOT safety glasses.
12. SECURE WORK. Use clamps or a vise to hold
work when practical. It is safer than using your
hand and frees both hands to operate tool.
13. DO NOT OVER-REACH. Keep proper
footing and balance at all times.
14. MAINTAIN TOOLS WITH CARE. Keep
tools sharp and clean for best and safest
performance. Follow instructions for lubricating and changing accessories.
15. USE RECOMMENDED ACCESSORIES.
Consult the owner’s manual for recommended accessories. The use of improper
accessories may cause risk of injury.
LENGTH
AMP RATING 25ft 50ft 100ft
0-6 18 16 16
7-10 18 16 14
11-12 16 16 14
13-16 14 12 12
17-20 12 12 10
21-30 10 10 No
Safety Instructions For Power Tools
16. REDUCE THE RISK OF UNINTENTIONAL STARTING. On machines with magnet-
ic contact starting switches there is a risk of
starting if the machine is bumped or jarred.
Always disconnect from power source
before adjusting or servicing. Make sure
switch is in OFF position before reconnecting.
17. MANY WOODWORKING TOOLS CAN
“KICKBACK” THE WORKPIECE toward the
operator if not handled properly. Know what
conditions can create “kickback” and know
how to avoid them. Read the manual accompanying the machine thoroughly.
18. CHECK DAMAGED PARTS. Before fur-
ther use of the tool, a guard or other part
that is damaged should be carefully
checked to determine that it will operate
properly and perform its intended function.
Check for alignment of moving parts, binding of moving parts, breakage of parts,
mounting, and any other conditions that
may affect its operation. A guard or other
part that is damaged should be properly
repaired or replaced.
19. NEVER LEAVE TOOL RUNNING UNATTENDED. TURN POWER OFF. Do not
leave tool until it comes to a complete stop.
20. NEVER OPERATE A MACHINE WHEN
TIRED, OR UNDER THE INFLUENCE OF
DRUGS OR ALCOHOL. Full mental alert-
ness is required at all times when running a
machine.
21. NEVER ALLOW UNSUPERVISED OR
UNTRAINED PERSONNEL TO OPERATE THE MACHINE. Make sure any
instructions you give in regards to machine
operation are approved, correct, safe, and
clearly understood.
22. IF AT ANY TIME YOU ARE EXPERIENCING DIFFICULTIES performing the intend-
ed operation, stop using the machine! Then
contact our service department or ask a
qualified expert how the operation should
be performed.
-4- H4378/H4379 Slimline Bench Grinder
Additional Safety Instructions For Grinders
1. ALWAYS WEAR EYE PROTECTION!
2. MAKE SURE GRINDER IS SECURED
FIRMLY TO A BENCH OR STAND
BEFORE USE. Any “wobbles” must be
corrected by shimming or blocking before
operation.
3. BEFORE MOUNTING A NEW WHEEL,
BE SURE WHEEL RPM IS RATED AT
AN EQUAL OR HIGHER RPM THAN
THE GRINDER.
4. DO NOT GRIND ON THE SIDES OF
THE GRINDING WHEELS, unless they
are special wheels designed specifically
for this purpose.
5. ONLY USE FLANGES THAT ARE
INCLUDED WITH THE GRINDER.
6. WEAR AN APPROVED DUST MASK
OR RESPIRATOR. Grinding operations
produce dust.
7. REPLACE A CRACKED WHEEL IMMEDIATELY. DO NOT use a grinding wheel
that has cracks or flaws. Before using,
inspect each wheel. Handle wheels carefully to avoid bumping or dropping.
8. DO NOT stand directly in front of grinding
wheels when turning machine on.
9. PERFORM a “ring test” (see page 12) on
grinding wheels to ensure that they are
safe for use. Always inspect grinding
wheels before operation.
10. HOLD THE WORKPIECE FIRMLY
WHILE GRINDING.
11. DO NOT allow your hands to come into
contact with grinding wheels during operation. Abrasive accessories have the
ability to remove a lot of material, including skin, very quickly. However, do not
wear gloves while grinding, they may get
caught in the grinding wheel.
12. KEEP TOOL REST AS CLOSE AS
POSSIBLE TO GRINDING WHEEL.
13. NEVER GRIND BY PLACING THE
WORKPIECE ON TOP OF THE
WHEEL. The wheel may kick the work-
piece toward the operator. Always grind
on the downward part of the wheel.
No list of safety guidelines can be complete. Every shop environment is different.
Always consider safety first, as it applies to
your individual working conditions. Use
this and other machinery with caution and
respect. Failure to follow guidelines could
result in serious personal injury, damage to
equipment or poor work results.
To operate this or any power tool safely and
efficiently, become as familiar with it as
possible. The time you invest before you
begin to use your Model H4378/H4379 will
be time well spent. DO NOT operate this
machine until you are completely familiar
with the contents of this manual, or serious
personal injury may occur.
H4378/H4379 Slimline Bench Grinder -5-
110V Operation
SECTION 2: CIRCUIT REQUIREMENTS
If you find it necessary to use an extension cord
with the Model H4378/H4379, make sure the cord
is rated Hard Service (grade S) or better. Refer to
the chart in the standard safety instructions to
determine the minimum gauge for the extension
cord. The extension cord must also contain a
ground wire and plug pin. Always repair or replace
extension cords when they become worn or damaged.
Extension Cords
Grounding
This equipment must be
grounded. Verify that any
existing electrical outlet
and circuit you intend to
plug into is actually
grounded. Under no circumstances should the
grounding pin from any
three-pronged plug be
removed. Serious injury
may occur.
In the event of an electrical short, grounding
reduces the risk of electric shock by providing
electric current a path of least resistance. This
tool is equipped with a power cord having an
equipment-grounding conductor. See Figure 1B.
The outlet must be properly installed and grounded in accordance with all local codes and ordinances.
The Model H4378 is wired for 110V and will draw
2.5 amps. The Model H4379 is wired for 110V and
will draw 3.5 amps. If you operate this machine on
any circuit that is already close to its capacity, it
might blow a fuse or trip a circuit breaker.
However, if an unusual load does not exist and a
power failure still occurs, contact a qualified electrician or our service department.
A 10 amp dedicated circuit should be used with
this grinder. Always check to see if your current
wires are capable of handling a 10 amp load. If
you are unsure, consult the advice of a qualified
electrician.
Figure 1B. Typical 110V plug and outlet.
Figure 1A. Do not remove grounding pin.
-6- H4378/H4379 Slimline Bench Grinder
SECTION 3: INTRODUCTION
We are proud to offer the Grizzly Model
H4378/H4379 Slimline Bench Grinder. The Model
H4378/H4379 is part of a growing Grizzly family of
fine woodworking machinery. When used according to the guidelines set forth in this manual, you
can expect years of trouble-free, enjoyable operation and proof of Grizzly’s commitment to customer satisfaction.
The Model H4378 offers a
1
⁄3 HP, 3450 RPM
motor and a 6" grinding wheel. The Model H4379
offers a
1
⁄2 H.P., 3450 RPM motor and an 8" grind-
ing wheel.
A number of grinding wheels for the Model
H4378/H4379 are available through the Grizzly
catalog.
We are also pleased to provide this manual with
the Model H4378/H4379. It was written to guide
you through assembly, review safety considerations, and cover general operating procedures.
This manual represents our effort to produce the
best documentation possible. If you have any
comments regarding this manual, please write to
us at the address below:
Grizzly Industrial, Inc.
C
/O Technical Documentation
P.O. Box 2069
Bellingham, WA 98227-2069
Most importantly, we stand behind our machines.
If you have any service questions or parts
requests, please call or write us at the location
listed below:
Grizzly Industrial, Inc.
1203 Lycoming Mall Circle
Muncy, PA 17756
Phone: (570) 546-9663
Fax: (800) 438-5901
E-Mail: techsupport@grizzly.com
Web Site: http://www.grizzly.com
The specifications, drawings, and photographs
illustrated in this manual represent the Model
H4378/H4379 as supplied when the manual was
prepared. However, owing to Grizzly’s policy of
continuous improvement, changes may be made
at any time with no obligation on the part of
Grizzly. Whenever possible, though, we send
manual updates to all owners of a particular tool
or machine. Should you receive one, we urge you
to insert the new information with the old and keep
it for reference.
Commentary
Read the manual before
assembly and operation. Become familiar
with the machine and its
operation before beginning any work. Serious
personal injury may
result if safety or operational information is not
understood or followed.
H4378/H4379 Slimline Bench Grinder -7-
SECTION 4: ASSEMBLY
Unpacking
The Model H4378/H4379 is shipped from the
manufacturer in a carefully packed carton. If you
discover the machine is damaged after you have
signed for delivery, immediately call Customer
Service for advice.
When you are completely satisfied with the condition of your shipment, you should inventory its
parts.
Some metal parts may
have sharp edges on
them after they are
formed. Please examine
the edges of all metal
parts before handling
them. Failure to do so
could result in injury.
Piece Inventory
NOTICE
A full parts list and breakdown can be found
toward the end of this manual. For easier
assembly, or to identify specific parts, please
refer to the detailed illustrations at the end of
the manual.
After all the parts have been removed from the
carton, you should have:
• Grinder
• Bolts (4)
• Washers (6)
• Knobs (2)
• Adjustable Rests (2)
• Eye Shields (2)
• Spark Breakers (2)
• Cooling Tray
NOTICE
When mounted, the cooling tray can be easily damaged if the grinder is tipped forward.
-8- H4378/H4379 Slimline Bench Grinder
Mounting Tool Rests
The Model H4378/H4379 weighs 22/27 lbs. Make
sure the workbench on which you plan to mount
the grinder is sturdy enough to hold the weight of
the machine and any downward pressure that
may be applied during operation. The workbench
should have a level surface and be heavy, or
attached to the floor, so it will not move during
operation. To mount the grinder:
• Pick a spot on the workbench that will allow
enough room to move the size of an anticipated workpiece around the grinder. The
operator (and possibly bystanders) should
have enough room to stand out of the way in
an emergency.
• Mount the grinder to the workbench with
bolts that are long enough to exceed the
thickness of your workbench and the grinder
base. Secure each bolt with flat washers, a
lock washer and a hex nut. Because sizes
vary for each individual situation, the hardware in this step is not included with the
Model H4378/H4379.
• Mount the grinder in an area with proper
lighting and near electrical outlets. Lighting
should be bright enough to eliminate shadow
and prevent eye strain. Electrical circuits
should be dedicated or large enough to handle amperage requirements. Keep power or
extension cords clear of high-traffic areas.
Observe local electrical codes for proper
installation of new lighting, outlets, or circuits.
Make your shop “child safe.”
Ensure that your workplace
is inaccessible to children
by closing and locking all
entrances when you are
away. Never allow visitors in
your shop when assembling,
adjusting, or operating
equipment.
The tool rest provides a surface that can be used
to support the workpiece during grinding. Certain
types of grinding may require jigs or accessories
to assure the proper angle of the workpiece
against the wheel.
The tool rest attaches to the inward side of the
wheel guard; it should be positioned as close to
the grinding wheel as possible. Insert the
1
⁄2" x 1⁄4"
hex bolt with a flat washer and a lock washer
through the rest support, and thread it into the
tapped hole. Repeat this installation for the opposite side wheel. The tool rest can be adjusted by
loosening these bolts and moving the bracket.
Always retighten before using the machine.
Eye Shields
OSHA requires that the eye shield be positioned
between the grinding wheel and the operator’s
face during grinding. This lessens the possibility
of sparks or metal bits flying directly at the operator.
Attach each support bracket to the top end of the
wheel rim guards with the knob bolts. Note that
the brackets are slotted to allow up and down
adjustments.
Snap the eye shields into the grooves on the support brackets. The shields should be able to swivel up and down.
H4378/H4379 Slimline Bench Grinder -9-
SECTION 5: OPERATIONS
Keep loose clothing
rolled up and out of the
way of machinery and
keep hair pulled back.
Wear safety glasses during the entire operation
process. Failure to comply may result in serious
personal injury.
Using this machine produces dust which may
cause allergic reactions
and respiratory problems.
Use an approved dust
mask to protect yourself
from these hazards!
NOTICE
The following section was designed to give
instructions on the basic operations of this
grinder. However, it is in no way comprehensive of every grinder application. There are
many different grinding wheels and attachments available for grinders. WE STRONGLY
RECOMMEND that you read books, trade
magazines, or get formal training to maximize the potential of your machine.
Once mounting is complete and adjustments are
done to your satisfaction, you are ready to test the
machine.
Plug the grinder into the power source. Stand
away from the line of rotation of the wheel and
turn the grinder ON. The grinder should run
smoothly with little or no vibration or rubbing noises. Strange or unnatural noises should be investigated and corrected before operating the
machine further. If the grinder seems okay, stay
out of the line of rotation and let it run for 1-2 minutes to make sure the wheel is structurally sound.
If you cannot easily locate the source of an
unusual noise or vibration, feel free to contact our
service department for help.
Test Run
Disconnect power to the
machine when performing any maintenance,
assembly or adjustments. Failure to do this
may result in serious personal injury.
!
-10- H4378/H4379 Slimline Bench Grinder
Safe Grinding Wheel Care
Your safety when grinding depends, on a large
part, on the condition of the wheel during grinding.
A wheel in poor condition presents the possibility
of breaking apart during rotation and injuring the
operator and possibly causing property damage.
Here are some tips to help you avoid breaking
the wheel:
• Always transport, store and handle wheels
with care. Wheels may be damaged if they
are dropped or if heavy objects are stacked
on them.
• Select the right grinding wheel for the job. Do
not grind material that is not designed for the
wheel.
• Select the right machine for the wheel. A
machine that rotates at a higher RPM than
the wheel is rated for may cause the wheel to
fly apart.
•Mount the wheels properly. (See the “Wheel
Mounting” instructions on page 13 for guid-
ance.) Never use a wheel with the wrong
arbor size for the grinder.
• Do not abuse the wheel by jamming the work
into the grinding wheel with excessive force.
• Learn how to use the grinder and the grinding
wheels properly. Ask a trusted person with
experience or consult with your local library to
learn more.
• If using coolant, always spin it out of the
wheel before turning off the power.
• Grinding on side of the wheel may cause
wheel damage.
The grinder is a safe tool when used properly. In
addition to the safety instructions in this manual,
the most important safety consideration is to use
common sense at all times. What may be okay in
one situation, may not be safe in another.
Here are some tips to keep in mind while
grinding:
• Make sure all guards are in place.
• Remember that grinding often produces
sparks. DO NOT allow anyone to stand in the
path of the sparks. DO NOT grind near flammable liquids or gases.
• Maintain proper care of your wheels. Read
the “Wheel Care” instructions for ideas on
how to go about doing this.
• Wear the proper protective clothing.
Remember that particles flying off of a grinding wheel will be traveling very fast—prepare
for this. Wear safety glasses, a dust mask,
earplugs, a leather apron, arm guards, a
hardhat and heavy leather boots.
• Grasp the workpiece tight and properly support it on the tool rest during operation. DO
NOT lean into the workpiece in a manner that
may cause your hands to move into the spinning wheel if the workpiece slips off.
• Concentrate on the task at hand. STOP
grinding if other people are distracting you.
STOP grinding if your mind is on something
else.
•DONOT grind on the side of the wheel.
Although side grinding is permissible for
some wheel types, the Model H4378/H4379
is not designed for side grinding.
H4378/H4379 Slimline Bench Grinder -11-
The Grit Size is a number that refers to the size of
the abrasive grain in the wheel. The lower the
number, the coarser the wheel. 10 is a very
coarse wheel for roughing and 220 is usually the
upper range for fine finish work.
Grade is an indication of the hardness of the
wheel—“A” being the softest and “Z” being the
hardest.
Bond Type refers to the type of bonding material
used to hold the abrasive material. Most general
purpose wheels will have a “V” indicating Vitrified
Clay is used. Vitrified Clay provides high strength
and good porosity. The other common bond type
is “B” for resin where synthetic resins are used.
These are used to grind cemented carbide and
ceramic materials.
There may be other numbers inserted that have
meaning for a particular type of wheel. Refer to
the manufacturer’s technical data for a complete
explanation.
The Model H4378 only accepts Type-1 wheels
with a
1
⁄
2
" bore. The Model H4379 only accepts
Type-1 wheels with a 5⁄8" bore.
Aluminum oxide and silicon carbide wheels are
marked in a somewhat uniform manner by all the
major manufacturers. Understanding these markings will help you understand the capabilities of
various wheels. Always refer to the manufacturer’s grinding recommendations when selecting a
wheel for your project.
The basic format for wheel numbering is:
Prefix Abrasive Grit Grade Bond
Type Size Type
1A60LV
The Prefix is the manufacturer’s designation for a
particular type.
The most common Abrasive Types used are A for
Aluminum Oxide and C for Silicon Carbide, and
occasionally SG for Seeded Gel.
Wheel Selection
-12- H4378/H4379 Slimline Bench Grinder
Wheel Inspection
Before mounting a new grinding wheel, it must be
inspected. Do not assume that a wheel is in sound
condition just because it is new—often, damage
can occur in shipping, with age, or with exposure
to moisture.
First, the wheel should be given a Visual
Inspection. Look for any cracks, chips, nicks or
dents in the surface of the wheel. If you see any
of these, DO NOT use the wheel.
Second, the wheel should be given a Ring Test.
This test will give you an indication of any internal
damage that may not be obvious during a visual
inspection.
To perform a Ring Test:
1. Make sure the wheel that you test is clean
and dry; otherwise, you may get false results.
2. If size permits, balance the wheel with your
finger in the hole. If this is not possible, hang
the wheel in the air with a piece of cord or
string looped through the hole in the center.
3. At the spots shown in Figure 2, gently tap the
wheel with a light non-metallic device such as
the handle of a screwdriver or a wooden mallet.
Figure 2. Ring test tapping locations.
4. An undamaged wheel will emit a clear metal-
lic ring or “ping” sound in each of these spots.
A damaged wheel will respond with a dull
thud that has no clear tone.
5. If you determine from the ring test that the
wheel is damaged, DO NOT use it!
STOP
Rated 3500 RPM
Make sure your grinder is not
faster than the rated RPM of this wheel
Type-1
Aluminum
Oxide
Grinding can be dangerous
Visually inspect this wheel
for cracks, nicks,chips
WARNING
60 Grit
Grade L
Vitrified Bond
H4378/H4379 Slimline Bench Grinder -13-
NEVER assemble a grinding wheel on the
arbor without paper or fiber discs between
the wheel and the flange. Omitting the discs
can put undue stress on the wheel, causing
it to crack and possibly fall apart.
ALWAYS visually inspect and perform a
“ring test” on a wheel before assembly. DO
NOT use damaged wheels!
Wheel Mounting
The wheel guard assembly must be removed in
order to mount or dismount a grinding wheel. To
do this:
1. Disconnect the grinder from the power
supply!
2. Remove the 3 Phillips head screws and nuts
that go through the outer guard. Take off the
outer guard and the rim guard.
3. Use a wrench on the nut that holds the wheel
on the arbor. Hold the wheel from turning
with your other hand. Note that the wheel on
the left-hand side of the machine is a lefthanded thread, so loosening it will require
turning it clockwise.
4. Remove the outer wheel flange and the
paper disc. Pull the wheel free from the
arbor. There will also be a paper disc and a
wheel flange on the back side of the wheel.
5. Mount the new wheel in the reverse order or
as shown in Figure 3. Always make certain
there is a paper or fiber disc between the
wheel flanges and the wheel itself. Tighten
the nut snugly but DO NOT over-tighten.
Over-tightening can crack the wheel.
6. Re-install the guards and shields.
7. Run a new wheel for at least 1-2 minutes
while standing clear of the line of rotation. If a
wheel does have defects it will generally fail
as soon as it gets up to full speed.
Figure 3. Wheel mounting order.
Flange
Flange
Nut
Wheel
Paper/Fiber
Disc
Paper/Fiber
Disc
u
m
n
i
m
u
l
A
M
P
R
0
0
5
3
t
r
i
f
i
e
d
B
o
n
d
n
O
x
i
d
e
T
y
p
e
-
1
V
i
-14- H4378/H4379 Slimline Bench Grinder
SECTION 6: MAINTENANCE
Always be aware of the condition of your grinder.
Routinely check the condition of the following
items and repair or replace as necessary:
• Loose mounting bolts
• Worn switch
• Worn or damaged cord
• Worn or damaged support bearings or guide
bearings
• Damaged grinding wheel
• Any other condition that could hamper the
safe operation of this machine.
General
Sealed and pre-lubricated ball bearings require
no lubrication for the life of the bearings. All bearings are standard sizes, and replacements can be
purchased from our parts department or a bearing
supply store.
Lubrication
The grinding wheel should be inspected before
every use. Use the “ring test” method from page
12 “Wheel Mounting” instructions to verify the
structural integrity. If using coolant during grinding, always run the wheel for 5-10 minutes at the
end of the operation to remove any coolant from
the wheel. Take care in storing grinding wheels to
keep them free from potential damage by being
dropped or having other items dropped on them.
Replace the wheel when the wheel diameter is
reduced to 4" on the Model H4378 and 6" on the
Model H4379. Operating at anything less than this
diameter does not allow the proper alignment of
the tool rest and the eye shield.
Depending on the type of grinding you do, the
grinding wheel may require periodic dressing.
There are several different types of wheel dressing devices available on the market. Use a suitable diamond or silicon carbide stick type dresser. Sweep it smoothly and evenly several times
across the face of the wheel. Dressing restores
the abrasive quality of the wheel surface, plus it
will bring the wheel edge back to a square form.
Refer to the instructions that accompany your
dressing accessory for complete details on wheel
dressing.
Grinding Wheels
Disconnect power to the
machine when performing any maintenance,
assembly or adjustments. Failure to do this
may result in serious
personal injury.
NOTICE
If the grinder is unmounted from the workbench for maintenance, the cooling tray can
be easily damaged if the grinder is tipped forward.
!
H4378/H4379 Slimline Bench Grinder -15-
Maintenance Performed
Approximate Hours Of Use
Maintenance Notes
Date
-16- H4378/H4379 Slimline Bench Grinder
The following pages contain general machine
data, parts diagrams/lists, a troubleshooting guide
and Warranty/Return information for your Model
H4378/H4379.
If you need parts or help in assembling your
machine, or if you need operational information,
we encourage you to call our Service Department.
Our trained service technicians will be glad to help
you.
If you have comments dealing specifically with
this manual, please write to our Bellingham,
Washington location using the address in Section
3: Introduction.
We have included some important safety measures that are essential to the operation of this
machine. While most safety measures are generally universal, Grizzly reminds you that each
workshop is different and safety rules should be
considered as they apply to your specific situation.
We recommend you keep a copy of our current
catalog for complete information regarding
Grizzly's warranty and return policy. If you need
additional technical information relating to this
machine, or if you need general assistance or
replacement parts, please contact the Service
Department listed in Section 3: Introduction.
Additional information sources are necessary to
realize the full potential of this machine. Trade
journals, woodworking magazines, and your local
library are good places to start.
SECTION 8: CLOSURE
The Model H4378/H4379 was specifically
designed for grinding. DO NOT MODIFY
AND/OR USE THIS MACHINE FOR ANY
OTHER PURPOSE. Modifications or
improper use of this tool will void the warranty. If you are confused about any aspect
of this machine, DO NOT use it until all
your questions have been answered or
serious personal injury may occur.
Like all power tools, there is danger associated with the Model H4378/H4379.
Accidents are frequently caused by lack of
familiarity or failure to pay attention. Use
this tool with respect and caution to lessen
the possibility of operator injury. If normal
safety precautions are overlooked or
ignored, serious personal injury may
occur.
Operating this equipment creates the potential for flying debris to cause eye injury.
Always wear safety glasses or goggles
when operating equipment. Everyday glasses or reading glasses only have impact
resistant lenses, they are not safety glasses.
Be certain the safety glasses you wear meet
the appropriate standards of the American
National Standards Institute (ANSI).
This section covers the most common problems encountered in grinding and what to do about them. Do
not make any adjustments until grinder is unplugged and moving parts have come to a complete stop.
TROUBLESHOOTING
SYMPTOM
Motor will not start.
Motor will not start; fuses or
circuit breakers blow.
Motor overheats.
Motor stalls (resulting in
blown fuses or tripped circuit).
Machine slows when operating.
Wavy condition on surface
of workpiece.
Lines on surface of workpiece.
Burning spots or cracks in
the workpiece.
Wheel dulls quickly, grit falls
off.
Wheel clogs and workpiece
shows burn marks.
POSSIBLE CAUSE
1. Low voltage.
2. Open circuit in motor or loose
connections.
1. Short circuit in line cord or plug.
2. Short circuit in motor or loose
connections.
3. Incorrect fuses or circuit breakers in power line.
1. Motor overloaded.
1. Short circuit in motor or loose
connections.
2. Low voltage.
3. Incorrect fuses or circuit breakers
in power line.
4. Motor overloaded.
1. Depth of cut too great.
1. Machine vibrating.
2. Workpiece not being held firmly.
3. Wheel face uneven.
4. Wheel is too hard.
1. Impurity on wheel surface.
2. Workpiece not being held tightly.
1. Improper type of grinding wheel.
2. Improper feed rate.
3. Coolant required.
1. Depth of cut too great.
2. Wheel is too soft.
3. Wheel diameter too small.
4. Bad wheel dress.
5. Defective wheel bonding.
1. Wheel is too hard.
2. Feed rate too slow.
3. Bad wheel dress.
4. Coolant required.
CORRECTIVE ACTION
1. Check power line for proper voltage.
2. Inspect all lead connections on motor for loose or open connections.
1. Inspect cord or plug for damaged insulation and shorted wires.
2. Inspect all connections on motor for loose or shorted terminals or
worn insulation.
3. Install correct fuses or circuit breakers.
1. Reduce load on motor.
1. Inspect connections on motor for loose or shorted terminals or
worn insulation.
2 Correct the low voltage conditions.
3. Install correct fuses or circuit breakers.
4. Reduce load on motor.
1. Slow down the rate of movement of the workpiece into wheel.
1. Make sure machine is securely mounted on a solid surface.
2. Use a holding device to firmly retain the workpiece.
3. Dress the grinding wheel.
4. Use softer wheel, or reduce the feed rate.
1. Dress the grinding wheel.
2. Use a holding device to firmly retain the workpiece.
1. Try a wheel which is softer style or a coarser grit.
2. Slow down the rate of movement of the workpiece into wheel.
3. Add optional coolant system or introduce coolant by hand.
1. Slow down the rate of movement of the workpiece into wheel.
2. Wheel too soft for the material being ground, select harder bond.
3. Replace the wheel.
4. Dress the wheel.
5. Consult manufacturer of grinding wheel.
1. Wheel too hard for the material being ground, select softer bond.
2. Increase the rate of movement of the workpiece into wheel.
3. Dress the wheel.
4. Add optional coolant system or introduce coolant by hand.
H4378/H4379 Slimline Bench Grinder -17-
Disconnect power to the
machine when performing any maintenance,
assembly or adjustments. Failure to do this
may result in serious
personal injury.
!
Customer Service #: (570) 546-9663 • To Order Call: (800) 523-4777 • Fax #: (800) 438-5901
MODEL H4378 SLIMLINE BENCH GRINDER
MACHINE DATA
SHEET
H4378/H4379 Slimline Bench Grinder-18-
Design Type.......................................................................... Bench Model
Overall Dimensions:
Height ..............................................................................................10"
Width............................................................................................18
5
⁄16"
Depth ..............................................................................................10"
Shipping Weight ........................................................................25 lbs.
Net Weight..................................................................................22 lbs.
Box Size ......................................................17
1
⁄2" L x 91⁄4" W x 101⁄2" H
Footprint..................................................................................8" x 7
5
⁄16"
Arbor ................................................................................................
1
⁄2"
Wheel Size ................................................................................6" x
3
⁄4"
Motor:
Type ....................................................TEFC Capacitor-Start Induction
Horsepower ..................................................................................
1
⁄3
HP
Phase / Voltage ....................................................Single-Phase ⁄ 110V
Amps (No Load) ..............................................................................2.5
Cycle / RPM ........................................................60 Hertz ⁄ 3450 RPM
Bearings ......................................Shielded & Permanently Lubricated
Features:
......................................................................................Wheel Flanges
............................................................................................Tool Rests
..............................................................................Rocker-Type Switch
....................................................Extended Wheel-to-Motor Clearance
........................................................................Convenient Water Tray
..............................Included 36 Grit Aluminum Oxide Grinding Wheel
..............................Included 60 Grit Aluminum Oxide Grinding Wheel
Specifications, while deemed accurate, are not guaranteed.
H4378/H4379 Slimline Bench Grinder -19-
Customer Service #: (570) 546-9663 • To Order Call: (800) 523-4777 • Fax #: (800) 438-5901
MODEL H4379 SLIMLINE BENCH GRINDER
MACHINE DATA
SHEET
Design Type.......................................................................... Bench Model
Overall Dimensions:
Height............................................................................................10
1
⁄2"
Width............................................................................................18
7
⁄16"
Depth ..........................................................................................10
13
⁄16"
Shipping Weight ........................................................................30 lbs.
Net Weight..................................................................................27 lbs.
Box Size ..........................................................18" L x 11" W x 11
1
⁄4" H
Footprint..................................................................................8" x 7
5
⁄16"
Arbor ................................................................................................
5
⁄8"
Wheel Size ................................................................................8" x
3
⁄4"
Motor:
Type ....................................................TEFC Capacitor-Start Induction
Horsepower ................................................................................
1
⁄2
" HP
Phase / Voltage ....................................................Single-Phase ⁄ 110V
Amps (No Load) ..............................................................................3.5
Cycle / RPM ........................................................60 Hertz ⁄ 3450 RPM
Bearings ......................................Shielded & Permanently Lubricated
Features:
......................................................................................Wheel Flanges
............................................................................................Tool Rests
..............................................................................Rocker-Type Switch
....................................................Extended Wheel-to-Motor Clearance
........................................................................Convenient Water Tray
..............................Included 36 Grit Aluminum Oxide Grinding Wheel
..............................Included 60 Grit Aluminum Oxide Grinding Wheel
Specifications, while deemed accurate, are not guaranteed.
-20- H4378/H4379 Slimline Bench Grinder
15
35
34
19
20
28
2
27
43
24
4
14
6
26
25
48
46
18
30
21
44
13
48
CBB60
32
22
47
33
31
29
41
14
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18
9
16
37
23
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3
H4378/H4379 Slimline Bench Grinder -21-
Ref# Part# Description
02 PH4378002 COVER
03 PN06 HEX NUT
1
⁄2"
04 PH4378004 FLANGE
05 PH4378005 GRINDER WHEEL
06 PH4378006 FLANGE
07 PH4378007 WHEEL GUARD
09 PH4378009 SPARK BREAKER
13 PW06 FLAT WASHER
5
⁄16"
14 PH4378014 KNOB SCREW
1
⁄4"-20 X 3⁄8"
15 PH4378015 EYESHIELD
16 PH4378016 ADJUSTABLE REST
18 PB15 HEX BOLT
5
⁄16"-18 X 3⁄8"
19 PH4378019 BUSHING
20 P6202 BALL BEARING 6202-2RS
21 PH4378021 MOTOR STATOR
22 PH4378022 WIRE NUT
23 PH4378023 MOTOR SHAFT
24 PH4378024 SPARK BREAKER
25 PH4378025 ADJUSTABLE REST
26 PH4378026 WHEEL GUARD
Ref# Part# Description
27 PH4378027 GRINDER WHEEL
28 PN26 LEFT HAND HEX NUT
1
⁄2"
29 PH4378029 WIRE
30 PH4378030 STRAIN RELIEF
31 PH4378031 BACK B0DY
32 PH4378032 CAPACITOR CBB60
33 PS01 PHLP HD SCR 10-24 X
1
⁄2"
34 PH4378034 MACHINE ID LABEL
35 PH4378035 FRONT BODY
36 PS22 PHLP HD SCR 10-24 X
5
⁄8"
37 PH4378037 SWITCH
38 PH4378038 BASE PLATE
39 PH4378039 PAD
41 PH4378041 COOLING TRAY
42 PW03 FLAT WASHER #10
43 PH4378043 EYESHIELD CLIP
44 PS06 PHLP HD SCR 10-24 X
3
⁄8"
46 PH4378046 STRAIN RELIEF PLATE
47 PH4378047 CAPACITOR BRACKET
48 PS01 PHLP HD SCR 10-24 X 1"
Ref# Part# Description
02 PH4379002 COVER
03 PN04 HEX NUT
5
⁄8
"
04 PH4379004 FLANGE
05 PH4379005 GRINDER WHEEL
06 PH4379006 FLANGE
07 PH4379007 WHEEL GUARD
09 PH4378009 SPARK BREAKER
13 PW06 FLAT WASHER
5
⁄16"
14 PH4378014 KNOB SCREW 1⁄4"-20 X
3
⁄8"
15 PH4378015 EYESHIELD
16 PH4378016 ADJUSTABLE REST
18 PB15 HEX BOLT
5
⁄16"-18 X 3⁄8"
19 PH4379019 BUSHING
20 P6203 BALL BEARING 6203-2RS
21 PH4379021 MOTOR STATOR
22 PH4378022 WIRE NUT
23 PH4379023 MOTOR SHAFT
24 PH4378024 SPARK BREAKER
25 PH4378025 ADJUSTABLE REST
26 PH4379026 WHEEL GUARD
Ref# Part# Description
27 PH4379027 GRINDER WHEEL
28 PN27 LEFT HAND HEX NUT
5
⁄8"
29 PH4378029 WIRE
30 PH4378030 STRAIN RELIEF
31 PH4378031 BACK B0DY
32 PH4378032 CAPACITOR CBB60
33 PS01 PHLP HD SCR 10-24 X
1
⁄2"
34 PH4379034 MACHINE ID LABEL
35 PH4378035 FRONT BODY
36 PS22 PHLP HD SCR 10-24 X
5
⁄8"
37 PH4378037 SWITCH
38 PH4378038 BASE PLATE
39 PH4378039 PAD
41 PH4378041 COOLING TRAY
42 PW03 FLAT WASHER #10
43 PH4378043 EYESHIELD CLIP
44 PS06 PHLP HD SCR 10-24 X
3
⁄
8"
46 PH4378046 STRAIN RELIEF PLATE
47 PH4378047 CAPACITOR BRACKET
48 PS01 PHLP HD SCR 10-24 X 1"
MODEL H4378 PARTS
MODEL H4379 PARTS
-22- H4378/H4379 Slimline Bench Grinder
Grizzly Industrial, Inc. warrants every product it sells for a period of 1 year to the original purchaser from
the date of purchase. This warranty does not apply to defects due directly or indirectly to misuse, abuse,
negligence, accidents, repairs or alterations or lack of maintenance. This is Grizzly’s sole written warranty
and any and all warranties that may be implied by law, including any merchantability or fitness, for any particular purpose, are hereby limited to the duration of this written warranty. We do not warrant or represent
that the merchandise complies with the provisions of any law or acts unless the manufacturer so warrants.
In no event shall Grizzly’s liability under this warranty exceed the purchase price paid for the product and
any legal actions brought against Grizzly shall be tried in the State of Washington, County of Whatcom.
We shall in no event be liable for death, injuries to persons or property or for incidental, contingent, special, or consequential damages arising from the use of our products.
To take advantage of this warranty, contact us by mail or phone and give us all the details. We will then
issue you a “Return Number,” which must be clearly posted on the outside as well as the inside of the carton. We will not accept any item back without this number. Proof of purchase must accompany the merchandise.
The manufacturers reserve the right to change specifications at any time because they constantly strive to
achieve better quality equipment. We make every effort to ensure that our products meet high quality and
durability standards and we hope you never need to use this warranty.
Please feel free to write or call us if you have any questions about the machine or the manual.
Thank you again for your business and continued support. We hope to serve you again soon.
WARRANTY AND RETURNS
Name ____________________________________________________________________________________
Street ____________________________________________________________________________________
City ______________________________________________________________State________Zip_________
Phone Number_______________________E-Mail_______________________FAX________________________
MODEL # H4378/H4379 Slimline Bench Grinder Serial# ___________________ Order# ________________
The following information is given on a voluntary basis. It will be used for marketing purposes to help us develop better products and services. Of
course, all information is strictly confidential.
10. Which benchtop tools do you own? Check all that apply.
___1" x 42" Belt Sander ___6" - 8" Grinder
___5" - 8" Drill Press ___Mini Lathe
___8" Table Saw ___10" - 12" Thickness Planer
___8" - 10" Bandsaw ___Scroll Saw
___Disc/Belt Sander ___Spindle/Belt Sander
___Mini Jointer
___Other__________________________________________________
11. How many of the machines checked above are Grizzly? ____________
12. Which portable/hand held power tools do you own? Check all that apply.
___Belt Sander ___Orbital Sander
___Biscuit Joiner ___Palm Sander
___Circular Saw ___Portable Planer
___Detail Sander ___Saber Saw
___Drill/Driver ___Reciprocating Saw
___Miter Saw ___Router
___Other__________________________________________________
13. What machines/supplies would you like Grizzly Industrial to carry?
__________________________________________________________
__________________________________________________________
14. What new accessories would you like Grizzly Industrial to carry?
__________________________________________________________
__________________________________________________________
15. What other companies do you purchase your tools and supplies from?
__________________________________________________________
__________________________________________________________
16. Do you think your purchase represents good value?
___Yes ___No
17. Would you recommend Grizzly Industrial to a friend?
___Yes ___No
18. Would you allow us to use your name as a reference for Grizzly customers
in your area? Note: We never use names more than three times.
___Yes ___No
19. Comments:_________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
1. How did you learn about us?
___Advertisement ___Friend
___Catalog ___Card Deck
___World Wide Web
___Other__________________________________________________
2. Which of the following magazines do you subscribe to.
___American Woodworker ___Practical Homeowner
___Cabinetmaker ___Shop Notes
___Family Handyman ___Today’s Homeowner
___Fine Homebuilding ___WOOD
___Fine Woodworking ___Wooden Boat
___Home Handyman ___Woodshop News
___Journal of Light Construction ___Woodsmith
___Old House Journal ___Woodwork
___Popular Mechanics ___Woodworker
___Popular Science ___Woodworker’s Journal
___Popular Woodworking ___Workbench
___Other__________________________________________________
3. Which of the following woodworking/remodeling shows do you watch?
___Backyard America ___The New Yankee Workshop
___Home Time ___This Old House
___The American Woodworker ___Woodwright’s Shop
___Other__________________________________________________
4. What is your annual household income?
___$20,000-$29,999 ___$60,000-$69,999
___$30,000-$39,999 ___$70,000-$79,999
___$40,000-$49,999 ___$80,000-$89,999
___$50,000-$59,999 ___$90,000 +
5. What is your age group?
___20-29 ___50-59
___30-39 ___60-69
___40-49 ___70 +
6. How long have you been a woodworker?
___0 - 2 Years ___8 - 20 Years
___2 - 8 Years ___20+ Years
7. How would you rank your woodworking skills?
___Simple ___Advanced
___Intermediate ___Master Craftsman
8. What stationary woodworking tools do you own? Check all that apply.
___Air Compressor ___Panel Saw
___Band Saw ___Planer
___Drill Press ___Power Feeder
___Drum Sander ___Radial Arm Saw
___Dust Collector ___Shaper
___Horizontal Boring Machine ___Spindle Sander
___Jointer ___Table Saw
___Lathe ___Vacuum Veneer Press
___Mortiser ___Wide Belt Sander
___Other__________________________________________________
9. How many of your woodworking machines are Grizzly? _____________
WARRANTY CARD
FOLD ALONG DOTTED LINE
FOLD ALONG DOTTED LINE
GRIZZLY INDUSTRIAL, INC.
P.O. BOX 2069
BELLINGHAM, WA 98227-2069
Place
Stamp
Here
TAPE ALONG EDGES--PLEASE DO NOT STAPLE
Name_______________________________
Street_______________________________
City______________State______Zip______
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