Central Pneumatic 33171 User manual

3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit our Web site at: http://www.harborfreight.com
TO PREVENT SERIOUS INJURY,
READ AND UNDERSTAND ALL WARNINGS
AND INSTRUCTIONS BEFORE USE.
Copyright© 2005 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.
Manual Revised 11h
MINI AIR ANGLE DIE GRINDER
Model 33171
ASSEMBLY AND OPERATING INSTRUCTIONS
Due to continuing improvements, actual product may differ slightly from the product described herein.

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PRODUCT SPECIFICATIONS
SAVE THIS MANUAL
You will need this manual for the safety warnings and precautions, assembly, operating,
inspection, maintenance and cleaning procedures, 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 in the following
pages may result in re, and/or serious injury.
SAVE THESE INSTRUCTIONS
UNPACKING
When unpacking, check to make sure all the parts shown on the Parts List on page 9
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.
Collet Size 1/4”
Air Inlet 1/4” NPT
Maximum Air Pressure 90 PSI
Air Consumption 4 CFM @ 90 PSI
Maximum RPM 21,000
Length about 5”
Accessories Collet Wrench (Qty. 2)

Page 3SKU 33171 For technical questions, please call 1-800-444-3353.
WORK AREA
1. Keep your work area clean and well lit. Cluttered benches and dark areas invite
accidents.
2. Do not operate pneumatic tools in explosive atmospheres, such as in the
presence of ammable liquids, gases, or dust. Pneumatic tools create sparks
which may ignite ammables.
3. Keep bystanders, children, and visitors away while operating a pneumatic
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.
PERSONAL SAFETY
1. Stay alert. Watch what you are doing, and use common sense when operating
a pneumatic tool. Do not use a pneumatic tool while tired or under the inu-
ence of drugs, alcohol, or medication. A moment of inattention while operating
pneumatic tools may result in serious personal injury.
2. Dress properly. Do not wear loose clothing or jewelry. Contain long hair.
Keep your hair, clothing, and gloves away from moving parts. Loose clothes,
jewelry, or long hair can be caught in moving parts.
3. Avoid accidental starting. Be sure the Trigger (4) is off before connecting to
the air supply. Carrying pneumatic tools with your nger on the Trigger, or con-
necting pneumatic tools to the air supply with the Trigger on, invites accidents.
4. Remove both Spanners before turning on the tool. A Spanner (27) that is left
attached to a rotating part of the tool may result in personal injury.
5. Do not overreach. Keep proper footing and balance at all times. Proper foot-
ing and balance enables better control of the tool in unexpected situations.
6. Use safety equipment. Always wear ANSI approved safety goggles underneath
a full face shield, a dust mask or respirator, and hearing protection.
TOOL USE AND CARE
1. Use clamps or other practical ways to secure and support the workpiece to
a stable platform. Holding the work by hand is unstable and may lead to loss of
control. Only work on a workpiece that is properly secured.
2. 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.
3. Do not use the power tool if the Trigger (4) does not turn it on or off. Any tool
that cannot be controlled with its Trigger is dangerous and must be replaced.
4. Disconnect the air hose from the tool before making any adjustments, chang-
ing accessories, or storing the tool. Such preventive safety measures reduce

Page 4SKU 33171 For technical questions, please call 1-800-444-3353.
the risk of starting the tool accidentally.
5. Store idle tools out of reach of children and other untrained persons. Tools
are dangerous in the hands of untrained users.
6. Maintain tools with care. Do not use a damaged tool. Tag damaged tools “Do
not use” until repaired.
7. Check for misalignment or binding of moving parts, breakage of parts, loose
parts, and any other condition that may affect the tool’s operation. If dam-
aged, have the tool serviced before using. Many accidents are caused by poorly
maintained tools.
8. 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
1. Tool service must be performed only by qualied repair personnel. Service
or maintenance performed by unqualied personnel could result in a risk of injury.
2. When servicing a tool, use only identical replacement parts. Follow instruc-
tions in the “Inspection, Maintenance, And Cleaning” section of this manual.
Use of unauthorized parts or failure to follow maintenance instructions may create
a risk of injury.

Page 5SKU 33171 For technical questions, please call 1-800-444-3353.
SPECIFIC SAFETY RULES
1. Maintain labels and nameplates on the Grinder. These carry important information.
If unreadable or missing, contact Harbor Freight Tools for a replacement.
2. Always grip the Grinder rmly when operating the tool.
3. Always use accessories that have an RPM rating of at least 21,000 and a 1/4”
diameter shank. Using accessories not rated to meet the RPM capacity of this
tool or with an improperly sized shank can result in damaged accessories, personal
injury, and/or property damage.
4. Use clean, dry, regulated, compressed air at 90 PSI. Do not exceed the
recommended 90 PSI. Never use oxygen, carbon dioxide, combustible gases, or
any other bottled gas as a power source for this tool.
5. Always disconnect the Grinder from its compressed air supply source, and
squeeze the Trigger (4) to verify that the tool cannot operate before performing
any maintenance or services.
6. Before using the Grinder, make sure that any accessories are properly attached
to the tool. Make sure to wrench tighten the collet before use.
7. Check accessories for any signs of excessive wear or damage before use.
DO NOT USE DAMAGED ACCESSORIES.
8. Accessories may become hot while grinding. Allow accessories to completely
stop and cool before touching.
9. Allow the accessory to move at full speed before feeding them into the
workpiece. Do not force the accessory into the workpiece when grinding. Apply
moderate pressure, allowing it to grind without being forced. When turning off the
Grinder, allow the accessory to stop on its own; do not press against it to stop it.
10. Industrial applications must follow OSHA requirements.
11. WARNING! The brass components of this product contain lead, a chemical known to
the State of California to cause birth defects (or other reproductive harm). (California
Health & Safety code § 25249.5, et seq.)
12. WARNING! The warnings, precautions, and instructions discussed in this manual
cannot cover all possible conditions and situations that may occur. The operator
must understand that common sense and caution are factors which cannot be built
into this product, but must be supplied by the operator.

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AIR LINE CONNECTION
NOTE:
For additional references to the parts listed in the following pages,
refer to the Assembly Diagram at the end of this manual.
For best service you should incorporate an oiler, regulator, and inline lter, as shown in the
diagram above. Hoses, couplers, oilers, regulators, and lters are all available at Harbor
Freight Tools.
1. You will need to prepare a 1/4” air connector (not included) to connect to the Inlet
(10) on the Die Grinder. First, wrap the 1/4” air connector with pipe thread seal tape
before threading it into the Inlet (10). Connect the 3/8” ID Air Source Hose to a quick
connect coupler (not included), and then to the Die Grinder.
Note: If you are not using an automatic oiler system, before operation, add a few
drops of Pneumatic Tool Oil to the airline connection. Add a few drops more after
each hour of continual use.
2. Set the air pressure on the regulator to 90 PSI. Do not exceed the maximum air
pressure of 90 PSI.
3. Check the air connection for leaks. Disconnect from the air source.
Die
Grinder

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ACCESSORY INSTALLATION
1. Make sure the air supply is disconnected rst. Insert the Collet (24) into the
Collet Nut (25). Then, thread the Collet Nut onto the Spindle (33) a few turns.
(See Figure A.)
2. Insert the shank of the accessory upward into the ared end of the Collet (24).
3. Place the small end of the Spanner (27) on the flats of the Spindle
(33). Place the large end of the other Spanner (27) on the flats of the
Collet Nut (25). Then, tighten the Collet Nut to secure the accessory in place.
(See Figure B.)
SPANNER
(27)
TIGHTEN
FIGURE B
SPANNER
(27)
COLLET (24)
COLLET NUT (25)
SPINDLE (33)
COLLET NUT (25)
COLLET (24)
(NOT SHOWN)
FIGURE A
SAFETY LE-
VER (39)

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GRINDER OPERATION
1. WARNING! Always wear ANSI approved safety goggles underneath
a full face shield, a dust mask or respirator, and hearing protection when
operating the Grinder.
2. Place the material you will be working on into a vise, or otherwise clamp the mate-
rial so that it will not move around when you use the Grinder.
3. Grip the Grinder rmly. To begin, press the Safety Lever (39) forward and squeeze
the Trigger (4). (See Figure A, previous page.) Make sure to squeeze the Trigger
and allow the grinder to spin at full speed before you touch the accessory to the
material you will be working on.
4. The Grinder’s speed is variable. To adjust the speed of the Grinder, vary the pres-
sure on the Trigger (4).
5. Allow the accessory to do the work. Do not use excessive force to press the acces-
sory into the surface you are working on. If the Grinder stalls, immediately release
the Trigger (4) and pull the accessory off the surface.
6. When nished grinding, release pressure on the Trigger (4). Turn off the compres-
sor. Squeeze the Trigger to release any compressed air in the air line and tool.
Then, disconnect the Grinder from the air hose.
7. Make sure to store the Grinder in a safe, clean, dry location out of reach of children
and other unauthorized people.
INSPECTION, MAINTENANCE, AND CLEANING
1. WARNING! Always make sure the Safety Lever (39) is in its locked position,
and disconnect the Grinder from its compressed air supply before performing any
inspection, adjustments, maintenance, or cleaning.
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
air hoses, loose, cracked, or bent accessories, 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. Yearly, or more often if used on a regular basis, inject grease into the Grease
Fitting (37).
4. Daily: With a soft brush, cloth, or vacuum, remove all dust and debris from the Grinder.
5. WARNING! All maintenance, service, or repairs not listed in this manual
should only be performed by a qualied service technician.

Page 9SKU 33171 For technical questions, please call 1-800-444-3353.
NOTE:
Some parts are listed and shown for illustration purposes only,
and are not available individually as replacement parts.
PLEASE READ THE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS LIST AND ASSEMBLY
DIAGRAM IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER OR
DISTRIBUTOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO 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 STATES THAT ALL REPAIRS AND PARTS REPLACEMENTS SHOULD BE
UNDERTAKEN BY CERTIFIED 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.
PARTS LIST
Part Description Q’ty Part Description Q’ty
1 Housing 1 21 Air Regulator 1
2 Pin 1 22 Pinion Gear 1
4 Trigger 1 23 Retainer 1
5 Throttle Valve 1 24 Collet (1/4”) 1
7 O-ring 1 25 Collet Nut 1
8 Valve Spring 1 26 Housing Lock Ring 1
9 O-ring 1 27 Spanner 2
10 Inlet 1 28 Angle Head Housing 1
11 O-ring 1 30 Spindle Gear 1
12 Rotor Brush 1 31 Clamp Nut 1
13 Ball Bearing 2 32 Key 1
14 Rear End Plate 1 33 Spindle 1
15 Rotor 1 34 Bushing 1
16 Rotor Blade 4 37 Grease Fitting 1
17 Pin 2 38 Spring 1
18 Cylinder 1 39 Safety Lever 1
19 Front End Plate 1 40 Roll Pin 1
20 Ball Bearing 2

Page 10SKU 33171 For technical questions, please call 1-800-444-3353.
NOTE:
Some parts are listed and shown for illustration purposes only,
and are not available individually as replacement parts.
ASSEMBLY DIAGRAM

Page 11SKU 33171 For technical questions, please call 1-800-444-3353.
90 Day Warranty
Harbor Freight Tools Co. makes every effort to assure that its products meet
high quality and durability standards, and warrants to the original purchaser that
this product is free from defects in materials and workmanship for the period
of 90 days from the date of purchase. This warranty does not apply to damage
due directly or indirectly, to misuse, abuse, negligence or accidents, repairs or
alterations outside our facilities, criminal activity, improper installation, normal
wear and tear, or to lack of maintenance. 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 product. Some states do
not allow the exclusion or limitation of incidental or consequential damages, so
the above limitation of exclusion may not apply to you. THIS WARRANTY IS
EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS.
To take advantage of this warranty, the product or part must be returned to us
with transportation charges prepaid. Proof of purchase date and an explanation
of the complaint must accompany the merchandise. If our inspection veries the
defect, we will either repair or replace the product at our election or we may elect
to refund the purchase price if we cannot readily and quickly provide you with a
replacement. We will return repaired products at our expense, but if we determine
there is no defect, or that the defect resulted from causes not within the scope of
our warranty, then you must bear the cost of returning the product.
This warranty gives you specic legal rights and you may also have other rights
which vary from state to state.