Jet JNS-4031 Service manual

Operating Instructions and Parts Manual
3/8-inch Reversible Air Drill
Models JNS-4031 and JNS-4031KL
WMH TOOL GROUP
2420 Vantage Drive
Elgin, Illinois 60123 Part No. M-JNS4031
Ph.: 800-274-6848 Revision A 6/06
www.wmhtoolgroup.com Copyright © WMH Tool Group

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WARRANTY AND SERVICE
WMH Tool Group, Inc., warrants every product it sells. If one of our tools needs service or repair, one of our
Authorized Service Centers located throughout the United States can give you quick service. In most cases, any of
these WMH Tool Group Authorized Service Centers can authorize warranty repair, assist you in obtaining parts, or
perform routine maintenance and major repair on your JET® tools. For the name of an Authorized Service Center in
your area call 1-800-274-6848.
MORE INFORMATION
WMH Tool Group is consistently adding new products to the line. For complete, up-to-date product information, check
with your localWMH Tool Group distributor, or visit jettools.com.
WARRANTY
JET products carry a limited warranty which varies in duration based upon the product (MW = Metalworking, WW =
Woodworking).
WHAT IS COVERED?
This warranty covers any defects in workmanship or materials subject to the exceptions stated below. Cutting tools,
abrasives and other consumables are excluded from warranty coverage.
WHO IS COVERED?
This warranty covers only the initial purchaser of the product.
WHAT IS THE PERIOD OF COVERAGE?
The general JET warranty lasts for the time period specified in the product literature of each product.
WHAT IS NOT COVERED?
Five Year Warranties do not cover woodworking (WW) products used for commercial, industrial or educational
purposes. Woodworking products with Five Year Warranties that are used for commercial, industrial or education
purposes revert to a One Year Warranty. This warranty does not cover defects due directly or indirectly to misuse,
abuse, negligence or accidents, normal wear-and-tear, improper repair or alterations, or lack of maintenance.
HOW TO GET SERVICE
The product or part must be returned for examination, postage prepaid, to a location designated by us. For the name
of the location nearest you, please call 1-800-274-6848.
You must provide proof of initial purchase date and an explanation of the complaint must accompany the
merchandise. If our inspection discloses a defect, we will repair or replace the product, or refund the purchase price,
at our option. We will return the repaired product or replacement at our expense unless it is determined by us that
there is no defect, or that the defect resulted from causes not within the scope of our warranty in which case we will,
at your direction, dispose of or return the product. In the event you choose to have the product returned, you will be
responsible for the shipping and handling costs of the return.
HOW STATE LAW APPLIES
This warranty gives you specific legal rights; you may also have other rights which vary from state to state.
LIMITATIONS ON THIS WARRANTY
WMH TOOL GROUP LIMITS ALL IMPLIED WARRANTIES TO THE PERIOD OF THE LIMITED WARRANTY FOR
EACH PRODUCT. EXCEPT AS STATED HEREIN, ANY IMPLIED WARRANTIES OR MERCHANTABILITY AND
FITNESS ARE EXCLUDED. SOME STATES DO NOT ALLOW LIMITATIONS ON HOW LONG THE IMPLIED
WARRANTY LASTS, SO THE ABOVE LIMITATION MAY NOT APPLY TO YOU.
WMH TOOL GROUP 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. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR
CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATION OR EXCLUSION MAY NOT APPLY TO YOU.
WMH Tool Group sells through distributors only. The specifications in WMH catalogs are given as general information
and are not binding. Members of WMH Tool Group reserve the right to effect at any time, without prior notice, those
alterations to parts, fittings, and accessory equipment which they may deem necessary for any reason whatsoever.
JET® branded products are not sold in Canada by WMH Tool Group.

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1. Read and understand this entire manual before attempting assembly or operation.
2. Read and understand the warnings posted on the tool and in this manual. Failure to comply with all of
these warnings may cause serious injury.
3. Replace the warning labels if they become obscured or removed.
4. This drill is designed and intended for use by properly trained and experienced personnel only. If you
are not familiar with the proper and safe operation of an air operated drill, do not use until proper
training and knowledge have been obtained.
5. Do not use this tool for other than its intended use. If used for other purposes, WMH Tool Group
disclaims any real or implied warranty and holds itself harmless from any injury that may result from
that use.
6. Always wear approved safety glasses/face shields while using this drill. (Everyday eyeglasses only
have impact resistant lenses; they are not safety glasses.)
7. Wear ear protectors (plugs or muffs) if the noise exceeds normal levels.
8. Use gloves if needed when operating the drill. Keep hands and body away from the working area of
the tool.
9. Some dust created by power sanding, sawing, grinding, drilling and other construction activities
contains chemicals known to cause cancer, birth defects or other reproductive harm. Some examples
of these chemicals are:
• Lead from lead based paint.
• Crystalline silica from bricks, cement and other masonry products.
• Arsenic and chromium from chemically treated lumber.
Your risk of exposure 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 face or dust masks that are specifically designed to filter out microscopic
particles.
10. Do not operate this tool while tired or under the influence of drugs, alcohol or any medication.
11. Maintain proper balance and keep your footing at all times. Non-slip footwear or anti-skid floor strips
are recommended.
12. Before operating this drill, remove tie, rings, watches and other jewelry, and roll sleeves up past the
elbows. Remove all loose clothing and confine long hair.
13. Excessive air pressure and too much free rotation may decrease the life of the tool and may cause a
hazardous situation.
14. Check air hoses for wear, and keep them away from heat and sharp edges. Do not carry the drill by
the air hose.
15. Do not use this air tool near flammable objects or potentially explosive environments.
16. Do not leave a connected tool unattended. When not in use, disconnect tool from the air source.
17. Disconnect drill from air supply before making adjustments or changing accessories.
18. Keep work area clean and free of clutter.
19. Keep visitors a safe distance from the work area. Keep children away.bahblahbla
20. Give your work undivided attention. Looking around, carrying on a conversation and “horse-play” are
careless acts that can result in serious injury.
21. Do not force a tool or attachment to do a job for which it was not designed. The right tool will do the
job better and safer.

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22. Repetitive motions and/or exposure to constant vibration can be harmful to hands and arms. Take
breaks and relax your hands occasionally during extended operation of the drill.
23. Compressed air can be harmful if directed toward sensitive areas of the body, and may propel small
particles caught in the air stream. Exercise proper caution.
24. Use recommended accessories; improper accessories may be hazardous.
25. Maintain tools with care. Keep the drill clean and oiled for best and safest performance.
Specifications
Stock Number..............................................................JNS-4031..........................................JNS-4031KL
Drilling Cap (in.)..................................................................... 3/8.........................................................3/8
Free Speed (no load)(RPM).................................................1800......................................................1800
Required Air Pressure (PSI).................................................... 90..........................................................90
Average Air Consumption (CFM) .............................................. 6............................................................6
Air Inlet Diameter (in.).....................................................1/4 NPT.................................................1/4 NPT
Air Hose Inside Diameter (in.)................................................ 3/8.........................................................3/8
Vibration Value (m/s2)................................................................. .(according to EN12096) x:10,y:0.5,z:0.7
Overall Length (in.) ...............................................................8.07.......................................................8.07
Net Weight (lbs.)...................................................................2.76.......................................................2.76
The above specifications were current at the time this manual was published, but because of our policy of
continuous improvement, WMH Tool Group reserves the right to change specifications at any time and
without prior notice, without incurring obligations.
Record your purchase information here for quick reference:
Stock No.: Serial No.:
Purchased From: Date Purchased:

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Unpacking
The model 4031 includes a chuck key. The
model 4031KL does not include a chuck key.
Any missing parts or damage should be reported
immediately to your JET®distributor. Read this
instruction manual thoroughly for operation,
maintenance and safety instructions.
Operation
1. The drill must be properly lubricated before
operating. See “Maintenance” section for
lubricating instructions.
2. Install a bit (not provided) into the chuck.
Insert the chuck key into the hole on the
chuck and rotate the chuck key clockwise to
tighten the bit in the chuck; or, on the
keyless model tighten the chuck firmly by
hand. Make sure the bit is centered in the
chuck.
3. Remove the protective cap from the air inlet,
and connect the air supply hose. Make sure
the air pressure is set to 90psi.
IMPORTANT: Connecting a quick-change
coupling directly to the Air Drill is not
recommended, as vibration may cause the
connection to fail. Instead, add a leader
hose and install any quick-change couplings
farther down the line.
Maintenance
The drill should be lubricated daily (or before
each use) with air tool oil through the air inlet.
During continual operation, it should be re-oiled
every 1 to 2 hours. This can be done either with
an in-line oiler, or manually. If done manually,
proceed as follows:
1. Disconnect the air hose from the drill.
2. Place 4 or 5 drops of air tool oil* into the air
inlet (Figure 1).
[*NOTE: Air tool oil not provided. It may be
purchased from your JET dealer, or is
available at most major hardware and tool
stores. SAE #10 weight oil or sewing
machine oil may be used as a substitute. Do
not use detergent oil.]
Figure 1
3. Re-connect the air. Run the drill without load
for a few seconds to distribute the oil
throughout the tool.
4. When you are finished operating the air drill,
before storing it disconnect the air hose and
place 4 or 5 drops of air tool oil into the air
inlet; re-connect the air and run the tool for a
few seconds to distribute the oil.
5. Avoid storing the drill in very humid locations
which promotes rusting of internal
mechanisms, and always oil it before
storage.
Air Connection
1. Make sure that the air compressor supplies
clean air at the correct CFM for the drill.
2. Set air pressure to 90 psi.
Excess air pressure and/or
unclean air will shorten the tool’s life and
may create a hazardous situation.
3. Drain the water from the air compressor tank
daily, as well as any condensation from the
air lines. Water in the air line may enter the
tool and cause damage.
4. Change filters on the air system on a regular
basis.
5. Air line pressure should be increased
accordingly to compensate for extra long air
hoses (usually over 25 feet). Inside diameter
of the hose should be a minimum of 3/8”.

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Troubleshooting
Trouble Probable Cause Remedy
Air pressure is too low. Adjust air pressure to 90psi.
Air lines are twisted, or there is a
blockage in them. Untwist or clean out air lines.
Air compressor is malfunctioning, or is
not sufficient capacity for the tool. Replace air compressor.
Drill does not operate
at normal speed.
Air regulator is malfunctioning. Have regulator repaired or replaced at
an authorized service center.
No air pressure. Check air compressor and hoses. Make sure compressor is set at 90psi,
and air lines are not twisted.
Stops operating. Trigger or throttle valve is
malfunctioning. Have throttle valve/trigger inspected
and repaired at an authorized service
center.
Torque is diminished. Air leakage. Check connections at the air inlet, o-
rings, etc. Make adjustments/repairs
as needed.
Starts immediately as
soon as air is
connected without
trigger being pressed.
Throttle valve or trigger are
malfunctioning. Inspect and repair throttle valve and/or trigger.
Abnormal vibration
and/or excessive
heat develops in the
tool. Improper lubrication. Lubricate properly according to
instructions in this manual.

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Parts List for JNS-4031 and JNS-4031KL Air Drills
To order parts or reach our service department, call 1-800-274-6848 between 7:30 a.m. and 6:00 p.m.
(CST), Monday through Friday. Having the Model Number and Serial Number of your tool available when
you call will allow us to serve you quickly and accurately.
Index No. Part No. Description Size Qty
01.............JNS4031-01............ Chuck Screw...............................................M5....................................1
02.............JNS4031-02............ Chuck (for Model JNS-4031 only) ................ .........................................1
02KL.........JNS4031KL-02........ Keyless Chuck (for Model JNS-4031KL only).........................................1
03.............JNS4031-03............ Housing Sleeve ........................................... .........................................1
04.............JNS4031-04............ Bearing........................................................6201 .................................2
05.............JNS4031-05............ Gear Frame................................................. .........................................1
06.............JNS4031-06............ Roll Pin........................................................Ø4x14 mm........................3
07.............JNS4031-07............ Assembly Gear............................................ .........................................3
08.............JNS4031-08............ Inner Gear................................................... .........................................1
09.............JNS4031-09............ Washer........................................................ .........................................1
10.............JNS4031-10............ Front Plate................................................... .........................................1
11.............JNS4031-11............ Bearing........................................................626ZZ...............................1
12.............JNS4031-12............ Fixing Pin..................................................... .........................................1
13.............JNS4031-13............ Rotor ........................................................... .........................................1
14.............JNS4031-14............ Rotor Blade ................................................. .........................................5
15.............JNS4031-15............ Cylinder....................................................... .........................................1
16.............JNS4031-16............ Rear Plate................................................... .........................................1
17.............JNS4031-17............ Cushion....................................................... .........................................1
18.............JNS4031-18............ Bearing........................................................626ZZ...............................1
19.............JNS4031-19............ Screw..........................................................M4x6.................................1
20.............JNS4031-20............ Trigger......................................................... .........................................1
21.............JNS4031-21............ O-Ring.........................................................Ø14x1.5 mm.....................1
22.............JNS4031-22............ F/R Valve..................................................... .........................................1

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23.............JNS4031-23............ O-Ring.........................................................Ø6x1 mm..........................1
24.............JNS4031-24............ Valve Stem.................................................. .........................................1
25.............JNS4031-25............ Trigger Spring.............................................. .........................................1
26.............JNS4031-26............ O-Ring.........................................................Ø 8x2 mm.........................1
27.............JNS4031-27............ O-Ring.........................................................Ø18x2 mm........................1
28.............JNS4031-28............ O-Ring.........................................................Ø18x3 mm........................1
29.............JNS4031-29............ Trigger Base................................................ .........................................1
30.............JNS4031-30............ Pin...............................................................Ø2.5x24 mm.....................1
31.............JNS4031-31............ Main Housing............................................... .........................................1
32.............JNS4031-32............ Exhaust Deflector ........................................ .........................................1
33.............JNS4031-33............ Screw..........................................................M3x6.................................2
34.............JNS4031-34............ Air Inlet........................................................ .........................................1
35.............JNS4031-35............ Inlet Cover................................................... .........................................1
36.............JNS4031-36............ Chuck Key (for model JNS-4031 only) (not shown) ................................1
37.............JNS4031-WL........... Warning Label (not shown) .......................... .........................................1
WMH Tool Group
2420 Vantage Drive
Elgin, Illinois 60123
Phone: [phone]
www.wmhtoolgroup.com