Harbor Freight Tools 91082 Assembly And Operating Instructions Manual

®

Model 91082

ROTARY GRINDER
WITH LCD

ASSEMBLY AND OPERATING INSTRUCTIONS

3491 Mission Oaks Blvd., Camarillo, CA 93011

Visit our Web site at: http://www.harborfreight.com

Copyright© 2004 by Harbor Freight Tools®. All rights reserved. No portion of this

manual or any artwork contained herein may be reproduced in any shape or form

without the express written consent of Harbor Freight Tools.

For technical questions, please call 1-800-444-3353.

PRODUCT SPECIFICATIONS

Collet Capacity
Speed 5,000 to 33,000 RPM
Tool Length 9-1/2” L
Tool Diameter 2” Dia.
Tool Weight 1.5 Lbs.
Power Cord Length 81” L

Accessories listed on the Parts List (Page 14).

1

/16”, 3/32”, 1/8”

SAVE THIS MANUAL

Y ou will need this man ual for the safety warnings and precautions, assembl y ,
operating, inspection, maintenance and c leaning pr ocedures, parts list and assem­bly diagram. Keep your invoice with this manual. Write the invoice number on the
inside of the front cover. Keep this manual and invoice in a safe and dry place for
future reference.

GENERAL SAFETY RULES

WARNING!

READ AND UNDERSTAND ALL INSTRUCTIONS

Failure to follow all instructions listed below may result in

electric shock, fire, and/or serious injury .

SAVE THESE INSTRUCTIONS

WORK AREA

1. Keep your work area clean and well lit. Cluttered benches and dark areas

invite accidents.

2. Do not operate power tools in explosive atmospheres, such as in the

presence of flammable liquids, gases, or dust. Power tools create sparks

which may ignite the dust or fumes.

3. Keep bystanders, children, and visitors away while operating a power tool.

Distractions can cause you to lose control. Protect others in the work area from

debris such as chips and sparks. Provide barriers or shields as needed.

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ELECTRICAL SAFETY

4. Grounded tools must be plugged into an outlet properly installed and

grounded in accordance with all codes and ordinances. Never remove the

grounding prong or modify the plug in any way. Do not use any adapter

plugs. Check with a qualified electrician if you are in doubt as to whether

the outlet is properly grounded. If the tools should electrically malfunction or

break down, grounding provides a low resistance path to carry electricity away

from the user.

5. Double insulated tools are equipped with a polarized plug (one blade is

wider than the other). This plug will fit in a polarized outlet only one way. If

the plug does not fit fully in the outlet, reverse the plug. If it still does not

fit, contact a qualified electrician to install a polarized outlet. Do not

change the plug in any way. Double insulation eliminates the need for the

three wire grounded power cord and grounded power supply system.

6. Avoid body contact with grounded surfaces such as pipes, radiators,

ranges, and refrigerators. There is an increased risk of electric shock if your

body is grounded.

7. Do not expose power tools to rain or wet conditions. Water entering a power

tool will increase the risk of electric shock.

8. Do not abuse the Power Cord. Never use the Power Cord to carry the tools

or pull the Plug from an outlet. Keep the Power Cord away from heat, oil,

sharp edges, or moving parts. Replace damaged Power Cords immedi-

ately. Damaged Power Cords increase the risk of electric shock.

9. When operating a power tool outside, use an outdoor extension cord

marked “W-A” or “W”. These extension cords are rated for outdoor use, and

reduce the risk of electric shock.

PERSONAL SAFETY

10. Stay alert. Watch what you are doing, and use common sense when oper-

ating a power tool. Do not use a power tool while tired or under the influ-

ence of drugs, alcohol, or medication. A moment of inattention while operat-

ing power tools may result in serious personal injury.

11. Dress properly . Do not wear loose clothing or je welry. Contain long hair .

Keep your hair, c lothing, and glo ves a way from mo ving parts. Loose

clothes, jewelry, or long hair can be caught in moving parts.

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12. Avoid accidental starting. Be sure the P ower Switch is off bef ore plugging

in. Carrying power tools with your finger on the Power Switch, or plugging in

power tools with the Power Switch on, invites accidents.

13. Remove adjusting keys or wrenches before turning the power tool on. A

wrench or a key that is left attached to a rotating part of the power tool may result

in personal injury.

14. Do not overreach. Keep proper footing and balance at all times. Proper

footing and balance enables better control of the power tool in unexpected

situations.

15. Use safety equipment. Always wear eye protection. Dust masks, non-skid

safety shoes, hard hat, or hearing protection must be used for appropriate condi-

tions. Always wear ANSI approved goggles and heavy work gloves during use.

TOOL USE AND CARE

16. Use clamps (not included) or other practical ways to secure and support

the workpiece to a stable platform. Holding the work by hand or against your

body is unstable and may lead to loss of control.

17. Do not force the tool. Use the correct tool for your application. The correct

tool will do the job better and safer at the rate for which it is designed.

18. Do not use the power tool if the Power Switch does not turn it on or off.

Any tool that cannot be controlled with the Power Switch is dangerous and must

be replaced.

19. Disconnect the Power Cord Plug from the power source before making any

adjustments, changing accessories, or storing the tool. Such preventive

safety measures reduce the risk of starting the tool accidentally.

20. Store idle tools out of reach of children and other untrained persons. Tools

are dangerous in the hands of untrained users.

21. Maintain tools with care. Keep cutting tools sharp and clean. Properly

maintained tools with a sharp cutting edge are less likely to bind and are easier

to control. Do not use a damaged tool. Tag damaged tools “Do not use” until

repaired.

22. Check for misalignment or binding of moving parts, breakage of parts, and

any other condition that may affect the tool’s operation. If damaged, have

the tool serviced before using. Many accidents are caused by poorly main-

tained tools.

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23. Use only accessories that are recommended by the manufacturer for your

model. Accessories that may be suitable for one tool may become hazardous

when used on another tool.

SERVICE

24. Tool service must be performed only by qualified repair personnel. Service

or maintenance performed by unqualified personnel could result in a risk of injury.

25. When servicing a tool, use only identical replacement parts. Follow

instructions in the

manual. Use of unauthorized parts or failure to follow maintenance instructions

may create a risk of electric shock or injury.

“Inspection, Maintenance, And Cleaning”

section of this

SPECIFIC SAFETY RULES

1. Maintain labels and nameplates on the Grinder. These carry important infor-

mation. If unreadable or missing, contact Harbor Freight Tools for a replacement.

2. Maintain a safe working environment. Make sure there is adequate surround-

ing workspace. Always keep the work area free of obstructions, grease, oil, trash,

and other debris.

3. Always keep the extension cord away from moving parts on the tool.

4. When using a hand-held power tool, always maintain a firm grip on the tool

with both hands to resist starting torque.

5. Avoid unintentional starting. Make sure you are prepared to begin work

before turning on the Grinder.

6. Do not force the Grinder. This tool will do the work better and safer at

the speed and capacity for which it was designed.

7. Never leave the Grinder unattended when it is plugged into an electrical

outlet. Turn off the tool and unplug it from its electrical outlet before leaving.

8. Always unplug the Grinder from its electrical outlet before performing and

inspection, maintenance, or cleaning procedures.

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9. Never grind near people or combustible materials. Grinding metal generates

sparks that can injure bystanders or ignite combustible materials.

10. WARNING! Some dust created by power sanding, sawing, grinding, drilling,

and other construction activities, contain chemicals known (to the State of Cali-

fornia) to cause cancer, birth defects or other reproductive harm. Some ex-

amples of these chemicals are: lead from lead-based paints, crystalline silica

from bricks and cement or 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.

(California Health & Safety Code 25249.5, et seq.)

11. WARNING! People with pacemakers should consult their physician(s)

before using this product. Electromagnetic fields in close proximity to a heart

pacemaker could cause interference to or failure of the pacemaker.

In addition, people with pacemakers should adhere to the following:

- Avoid operating power tools alone.

- Don’t use a power tool with the power switch locked on.

- If powered via a power cord be certain that the tool is properly grounded. A ground

fault interrupt (GFCI) system is also a good precaution. This inexpensive device is

a good safety measure because it prevents a sustained electrical shock.

- Properly maintain and inspect all tools before use to avoid electrical shock.

12. WARNING! Working in awkward positions, excessive exposure to vibra-

tion, and repetitive work motions can cause injury to hands and arms. Stop using

the tool if any discomfort , numbness, tingling, or pain occurs. Consult a doctor

as soon as possible.

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GROUNDING

WARNING!

Improperly connecting the grounding wire can result in the risk of electric

shock. Check with a qualified electrician if you are in doubt as to whether the

outlet is properly grounded. Do not modify the power cord plug provided with

the tool. Never remove the grounding prong from the plug. Do not use the

tool if the power cord or plug is damaged. If damaged, have it repaired by

a service facility before use. If the plug will not fit the outlet, have a proper

outlet installed by a qualified electrician.

GROUNDED T OOLS: TOOLS WITH THREE PRONG PLUGS

1. Tools mar ked with “Grounding Required” have a three wire cord and three prong

grounding plug. The plug must be connected to a properly grounded outlet. If

the tool should electrically malfunction or break down, grounding provides a low

resistance path to carry electricity away from the user, reducing the risk of elec-

tric shock. (See Figure A.)

2. The grounding prong in the plug is connected through the green wire inside the

cord to the grounding system in the tool. The green wire in the cord must be the

only wire connected to the tool’s grounding system and must never be attached

to an electrically “live” terminal. (See Figure A.)

3. Your tool must be plugged into an appropriate outlet, properly installed and

grounded in accordance with all codes and ordinances. The plug and outlet

should look like those in the following illustration. (See Figure A.)

FIGURE A

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DOUBLE INSULA TED T OOLS: TOOLS WITH TWO PRONG PLUGS

4. Tools mar ked “Double Insulated” do not require grounding. They have a special

double insulation system which satisfies OSHA requirements and complies with

the applicable standards of Underwriters Laboratories, Inc., the Canadian

Standard Association, and the National Electrical Code. (See Figure B.)

5. Double insulated tools may be used in either of the 120 volt outlets shown in the

following illustration. (See Figure B.)

FIGURE B

EXTENSION CORDS

1.

2. As the distance from the supply outlet increases, you must use a heavier gauge

3. The smaller the gauge number of the wire, the greater the capacity of the cord.

4. When using more than one extension cord to make up the total length, make

Grounded

can use either a two or three wire extension cord.

extension cord. Using extension cords with inadequately sized wire causes a

serious drop in voltage, resulting in loss of power and possible tool damage.

(See Figure C, next page.)

For example, a 14 gauge cord can carry a higher current than a 16 gauge cord.

(See Figure C.)

sure each cord contains at least the minimum wire size required.

(See Figure C.)

tools require a three wire extension cord.

Double Insulated

tools

5. If you are using one extension cord for more than one tool, add the nameplate

amperes and use the sum to determine the required minimum cord size.

(See Figure C.)

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6. If you are using an extension cord outdoors, make sure it is marked with the

suffix “W-A” (“W” in Canada) to indicate it is acceptable for outdoor use.

7. Make sure your extension cord is properly wired and in good electrical condition.

Always replace a damaged extension cord or have it repaired by a qualified

electrician before using it.

8. Protect your extension cords from sharp objects, excessive heat, and damp or

wet areas.

RECOMMENDED MINIMUM WIRE GAUGE FOR EXTENSION CORDS*

(120 VOLT)

NAMEPLATE
AMPERES
(At Full Load)

25 FEET 50 FEET 75 FEET 100 FEET 150 FEET

0 - 2.0 18 18 16 16 16

2.1 - 3.4 18 18 16 14 14

3.5 - 5.0 18 18 16 14 12

5.1 - 7.0 18 16 14 12 12

7.1 - 12.0 18 14 12 10 -

12.1 - 16.0 14 12 10 - -

16.1 - 20.0 12 10 - - -

EXTENSION CORD LENGTH

FIGURE C

*Based on limiting the line voltage drop
to five volts at 150% of the rated amperes.

SYMBOLOGY

Double Insulated
Canadian Standards

Association
Underwriters

Laboratories, Inc.

V ~

A

n

o

xxxx/min.

Volts Alternating Current

Amperes

No Load Revolutions
per Minute (RPM)

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UNPACKING

When unpacking, check to make sure all the parts shown on the Parts List on
page 14 are included. If any parts are missing or broken, please call Harbor Freight Tools

at the number shown on the cover of this manual as soon as possible.

ASSEMBLY AND OPERATING INSTRUCTIONS

NOTE: For additional information regarding the parts listed in the following pages, refer

to the

Assembly Diagram on page 15.

1.

CAUTION: Always make sure the Power Cord of the Grinder is unplugged from

its electrical outlet

prior

to making any adjustments to the tool.

2. Attach an accessory to the Grinder by loosening the Collet Cap (15). First, press

down the Spindle Lock (12) and hold it down while loosening the Collet Cap (15)

with the wrench (included). See FIGURES 1 and 2.

Note: To exchange collets, completely remove existing collet using the same

procedure above. Replace with a new collet and tighten. See FIGURE 3.

3. Slide the accessory into the Collet (14) and tighten the Collet Cap (15) by holding

down the Spindle Lock (12) and using the wrench.

FIGURE 1

Power Switch

Speed Switch (1)

LCD (2)

Speed Switch (1)

Spindle Lock (12)

Collet Cap (15)

Loosening
Collet Cap (15)
with wrench

FIGURE 2

Wrench

Collet Cap (15)

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FIGURE 3

Replacing the Collet

Collet Cap (15)

Collet (14)

ASSEMBLY AND OPERATING INSTRUCTIONS (continued)

Using the Extension
Note: The 1/8” Collet must be attached to use the Flex Extension (30).

1. To install the Flex Extension (30) first remove the Motor Housing Nut (10) and set it

aside. Next, slide the spring around the shaft back and insert the shaft of the Flex

Extension (30) into the Collet (14) following the instructions on page 10. Tighten as

per same instructions. Tighten the nut on the Flex Extension (30) to take the place

of the Motor Housing Nut (10) you removed. See FIGURE 4.

2. To open the collet on the Flex Extension (30), pull back on the collar and turn the

Collet Cap until it locks. Loosen and tighten it with the wrench. See FIGURE 5.

FIGURE 4

Flex Extension (30)

FIGURE 5

Collet on tip
of Flex Extension

Using the Stand

Curved
Bar

Nut on Flex Extension

Motor Housing Nut (10)

FIGURE 6

Nut

Collet Cap (15)

Lock

Telescoping Stand (29)

Twist To Extend

Unlock

FIGURE 7

Nut

Placement

(For Alternate

Mounting)

Base (28)

Grinder on Stand.

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FIGURE 8

ASSEMBLY AND OPERATING INSTRUCTIONS (continued)

Using the Stand (continued)

Refer to FIGURES 6, 7, and 8 on page 11.

1. You may screw the Telescoping Stand (29) into the Base (28) as shown in FIG-

URES 6 and 8. Or, if you wish to install the unit so that the bar is facing out or

parallel to a shelf or workbench, you may remo v e the nut from the slot at the top of

the Base, insert it into the back of the Base (28), and install the Telescoping Stand

(29) there. See FIGURE 7.

2. The Telescoping Stand (29) extends in two places by twisting it to unlock, sliding it

into position, and twisting to lock it into place. On the end, you can turn the nut and

slide the curved bar out if necessary. See FIGURE 6.

Operating the Grinder

The best way to determine what speed to use, is to practice with the v arious attach­ments on scrap material. Y ou’ll learn to determine what is appropriate by making a pass at
your scrap material at various speeds. For example, when working with plastic, make a
pass a the scrap material at low speeds and then at higher speeds, to determine at what
speed the action begins to melt the material. Once you determine the melting point, just
back the speed down to find the optimum speed to operate at.

Tips:

1. Plastic and other materials that melt, should be worked on at low speeds.

2 . Polishing, b uffing, and cleaning with the wire brush should be done at speeds

less than 15,000 RPM, to avoid damaging the brush.

3. Wood should be cut at high speeds.
Note: Never press or lean on the Grinder to make it cut faster. You may
damage the tool. Experiment with different cutting accessories and speeds
to improve cutting speed.

Make sure your workpiece is secure.

1. Flip the Power Switch to the on position.

2. The LCD displays the approximate speed in units
of 1000. It begins at “5”, representing 5,000 RPM,
and goes up to “33”, representing 33,000 RPM.
See FIGURE 9.

3. To increase speed, press the (+) Speed Switch (1).
To decrease speed, press the (-) Speed Switch (1)

4. When finished, turn off the Power Switch and unplug
the Grinder.

Power Switch

FIGURE 9

LCD (2)

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Speed Switch (1)

INSPECTION, MAINTENANCE, AND CLEANING

1. WARNING! Make sure the Power Switch of the Grinder is in its “OFF”
position and that the tool is unplugged from its electrical outlet before performing
any inspection, maintenance, or cleaning procedures.

2. BEFORE EACH USE, inspect the general condition of the Grinder. Check for
loose screws, misalignment or binding of moving parts, cracked or broken parts,
damaged electrical wiring, and any other condition that may affect its safe opera­tion. If abnormal noise or vibration occurs, have the problem corrected before
further use. Do not use damaged equipment.

3. Wipe the tool clean with a lint free cloth. Do not use harsh detergents or solvents
to clean the tool.

4. Excessive sparking or diminished performance means your Carbon Brushes (7)
need to be replaced. Have the Carbon Brushes (7) replaced by an authorized
technician

5. Make sure the Collet (14) is always clean and clear of dirt, grease, and debris.

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PARTS LIST

Part Description Qty. Part Description Qty.
1 Speed Switch 1 15 Collet Cap 1
2 LCD 1 16 Armature 1
3 Lens 1 17 Bearing 625 1
4 PC Board 1 18 Rubber Sleeve 1
5 Label 1 19 Stator 1
6 Carbon Brush Spring 2 20 Tap Screw 2
7 Carbon Brush 2 21 Press Cord Board 1
8 Carbon Brush Holder 2 22 Tap Screw 2
9 Left Motor Housing 1 23 Power Cord Sheath 1
10 Motor Housing Nut 1 24 Hook 1
11 Spring 1 25 Power Cord 1
12 Spindle Lock 1 26 Tap Screw 5
13 Bearing 608Z3 1 27 Right Motor Housing 1
14

1

/8” Collet 1 28 Base 1

29 Telescopic Stand 1
30 Flex Extension 1

Accessories:

1

/16” Collet (1),3/32” Collet (1), 3/8” Wrench (1), Grinding Stones (7),

Steel Wire Wheel (1), Buffer Pad (1), Nylon Bristle Brush (1),

High Speed Cutters (6), Sanding Drum (1), Sanding Bands (4),

Cutoff Wheel Mandrel (1), Cutoff Wheels (4), Sanding Disks (4),

Felt Bob Mandrel (1), Felt Bob (1), Drill Bits (4)

PLEASE READ THE FOLLOWING CAREFULLY

THE MANUF A CTURER AND/OR DISTRIBUT OR HAS PR O VIDED THE PARTS LIST AND ASSEMBLY
DIAGRAM IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUF ACTURER OR
DISTRIBUTOR MAKES ANY REPRESENTA TION OR W ARRANTY OF ANY KIND T O THE BUYER THAT
HE OR SHE IS QUALIFIED TO MAKE ANY REPAIRS TO THE PRODUCT, OR THAT HE OR SHE IS
QUALIFIED TO REPLACE ANY PARTS OF THE PRODUCT. IN FACT, THE MANUFACTURER AND/
OR DISTRIBUTOR EXPRESSLY ST ATES THA T ALL REP AIRS AND PARTS REPLACEMENTS SHOULD
BE UNDERTAKEN BY CER TIFIED AND LICENSED TECHNICIANS, AND NOT BY THE BUYER. THE
BUYER ASSUMES ALL RISK AND LIABILITY ARISING OUT OF HIS OR HER REPAIRS TO THE
ORIGINAL PRODUCT OR REPLACEMENT PARTS THERETO, OR ARISING OUT OF HIS OR HER
INSTALLATION OF REPLACEMENT PARTS THERETO.

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ASSEMBLY DIAGRAM

NOTE: Some parts are listed and shown for illustration purposes only, and are not

available individually as replacement parts.

SKU 91082 Page 15