Chicago Electric 91220 User manual

MINI ARC WELDER - 40 AMP
Model 91220
ASSEMBLY AND OPERATING INSTRUCTIONS
3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit ourWeb 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.
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PRODUCT SPECIFICATIONS
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.
SAVETHESE INSTRUCTIONS
WORK AREA
1. Keep your work area clean and well lit. Cluttered benches and dark areas
invite accidents.
2. Do not operate welders in explosive atmospheres, such as in the presence
of flammable liquids, gases, or dust. Welders create sparks which may
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SAVE THIS MANUAL
You will need this manual for the safety warnings and precautions, assembly, oper-
ating, 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.
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 FreightTools
at the number shown on the cover of this manual as soon as possible.
UNPACKING
Item Description
Electrical Requirements Input Power: 110 VAC / 15 AMP’s
Duty Cycle: 5% @ 40 AMP’s
Rated Load Voltage: 22 Volts
Welding Current: 40 AMP’s
Rated Output Power: 1.35 KW
Rated Input Power: 1.5 KVA
No Load Voltage: 35 Volts
2-Prong Power Plug
Electrode Sizes * 3/64” – 1/16”
Welding Capacity Up to 3/64” Steel Plate
Electrode Holder Standard Squeeze Handle
Ground Clamp Standard Zinc Plated, Spring Loaded
Overall Dimensions 8” H x 4-5/8” W x 6-5/8” L
Net Weight 14.65 Pounds
* The product includes 4 pieces of 1/16” Electrodes.
REV 09/04

3. Keep bystanders, children, and visitors away while operating a welder.
Distractions can cause you to lose control. Protect others in the work area from
arc rays, sparks, and slag. Provide barriers or shields as needed.
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 theWelder to rain or wet conditions. Water entering a welder
will increase the risk of electric shock.
8. Do not abuse the Power Cord. Never use the Power Cord to carry the
Welder or pull the Plug from an outlet. Keep the Power Cord away from
heat, oil, sharp edges, or moving parts. Replace damaged Power Cords
immediately. Damaged Power Cords increase the risk of electric shock.
9. When operating a welder 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 welder. Do not use a welder while tired or under the influence of
drugs, alcohol, or medication. A moment of inattention while operating weld-
ers may result in serious personal injury.
ignite the dust or fumes.
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11. 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.
12. Avoid accidental starting. Be sure the Power Switch is off before plugging
in. Plugging in welders with the Power Switch on invites accidents.
13. Do not overreach. Keep proper footing and balance at all times. Proper
footing and balance enables better control of the Welder in unexpected
situations.
TOOL USE AND CARE
14. 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 dangerous and may lead to loss of control and serious burns.
15. Do not force the Welder. Use the correct welder for your application. The
correct welder will do the job better and safer at the rate for which it is designed.
16. Do not use theWelder 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.
17. Disconnect the Power Cord Plug from the power source before making any
adjustments, changing accessories, or storing the Welder. Such preventive
safety measures reduce the risk of starting the tool accidentally.
18. Store idle tools out of reach of children and other untrained persons. Tools
are dangerous in the hands of untrained users.
19. Maintain theWelder with care. Properly maintained tools are easier to control.
Do not use a damaged tool. Tag damaged tools “Do not use” until repaired.
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20. Check for misalignment or binding of moving parts, broken parts, and
any other condition that may affect theWelder’s operation. If damaged,
have the tool serviced before using. Many accidents are caused by poorly
maintained tools.
21. Use only accessories that are recommended by the manufacturer for your
model. Accessories that may be suitable for one welder may become hazardous
when used on another welder.

SERVICE
22. Tool service must be performed only by qualified repair personnel. Service
or maintenance performed by unqualified personnel could result in a risk of injury.
23. When servicing a tool, use only identical replacement parts. Follow
instructions 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 electric shock, burns, or other injury.
Improperly connecting the grounding wire can result in the risk of electric
shock. Check with a qualfified 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.
DOUBLE INSULATEDTOOLS:TOOLS WITH TWO PRONG PLUGS
1. Tools marked “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 A.)
2. Double insulated tools may be used in either of the 120 volt outlets shown in the
following illustration. (See Figure A.)
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GROUNDING
WARNING!
FIGURE A
3. Your tool must be plugged into an appropriate outlet, properly installed and
grounded in accordance with all codes and ordinances. (See Figure A.)

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EXTENSION CORDS
1. Double Insulated tools can use either a two or three wire extension cord.
2. As the distance from the supply outlet increases, you must use a heavier gauge
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 B.)
3. The smaller the gauge number of the wire, the greater the capacity of the cord.
For example, a 14 gauge cord can carry a higher current than a 16 gauge cord.
When using more than one extension cord to make up the total length, make
sure each cord contains at least the minimum wire size required.
(See Figure B.)
4. 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 B.)
5. 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.
6. Protect your extension cords from sharp objects, excessive heat, and damp or
wet areas.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.
FIGURE B
RECOMMENDED MINIMUMWIRE GAUGE FOR EXTENSION CORDS*
(110VOLT)

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SYMBOLOGY
Double Insulated
Canadian Standards
Association
Underwriters
Laboratories, Inc.
Volts Alternating Current
Amperes
No Load Revolutions
per Minute (RPM)
noxxxx/min.
A
V ~
FIGURE C
SPECIFIC SAFETY RULES
1. Maintain a safe working environment. Keep the work area well lit. Make sure
there is adequate surrounding workspace. Always keep the work area free of ob-
structions, grease, oil, trash, and other debris. Do not use the Mini Arc Welder in
areas near flammable chemicals, dusts, and vapors.
2. Maintain labels and nameplates on the Mini ArcWelder. These carry important
information. If unreadable or missing, contact Harbor Freight Tools for a replace-
ment.
3. Never plug the Power Cord of this product into an electrical outlet while stand-
ing on a wet or damp surface.
4. Do not unplug the Mini Arc Welder by pulling on the Power Cord. Keep the
Power Cord away from heated surfaces.
5. Use eye, skin, and breathing protection. Always wear ANSI approved safety
glasses with side shields under an ANSI approved welding helmet. Wear fire resis-
tant work gloves, a heavy, long-sleeved shirt, trousers without cuffs, shoes with
high insteps to protect skin from arc rays and metal sparks. Also wear an ANSI
approved air respirator.
6. Always turn off the Mini Arc Welder and unplug the unit from its electrical
outletbeforeperforminganyinspection,maintenance,orcleaning procedures.
7. Never leave the Mini ArcWelder unattended when it is plugged into an electri-
cal outlet. Make sure to unplug it from its electrical outlet before leaving the area.
8. Do not allow children to handle or play with this product.

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9. Store idle equipment. When not in use, tools and equipment should be stored in
a dry location to inhibit rust. Always lock up tools and equipment, and keep out of
reach of children.
10. Do not use this product if under the influence of alcohol or drugs. Read
warning labels on prescriptions to determine if your judgement or reflexes are im-
paired while taking drugs. If there is any doubt, do not attempt to use this product.
11. Industrial applications must follow OSHA requirements.
12. Maintain this product with care. Keep this product clean and dry for better and
safer performance.
13. Maintenance: For your safety, service and maintenance should be performed
regularly by a qualified technician.
14. Check for damaged parts. Before using this product, carefully check that it will
operate properly and perform its intended function. Check for damaged parts and
any other conditions that may affect the operation of this product. Replace or repair
damaged or worn parts immediately.
15. Connect the earth ground as near as possible to the operating area. Earth
connections to structural parts of the building or other places distant to the operat-
ing area will reduce their effectiveness and increase the danger of electric shock.
16. Do not pass equipment cables through or near lifting chains,crane cables,or
any electrical lines.
17. In addition to grounding the workpiece with the Mini Arc Welder Grounding
Cable, an earth grounding of the workpiece is recommended. Ground it di-
rectly to an earth pipe or grounding rod with a separate cable of appropriate size
(not included). IMPORTANT:Only a qualified, certified electrician should perform
this procedure.
18. Do not touch the electrode if you are in contact with the workpiece,ground,or
another electrode from a different machine.
19. Never use the Mini ArcWelder near water. Ensure that the surrounding area and
cutting objects are dry. Do not spray water or other liquids on or near the Mini Arc
Welder.
20. Avoid all direct contact between the skin and wet garments and metal parts
under electrical power. Check that gloves and protective clothing are dry.
21. Always wear welding gloves and rubber soled shoes when working in damp
areas or standing on metal objects.
22. Always turn off the Mini ArcWelder in the event of a power failure.
23. Do not allow the Electrode Holder to touch earth ground. Accidental earth
discharges may cause overheating and fire hazards.
24. Significant DC voltage exists after turning off and unplugging the Inverter Arc
Welder. Discharge the electrode to ground before handling.
25. Position a fire-resistant screen (not included) around the welding area to pro-

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tect people in the vicinity from arc rays, sparks, and slag.
26. Clear away or protect flammable objects. Protect objects such as wood, saw-
dust,clothing,paints,solvents,petroleum products,natural gas,acetylene,propane,
and other substances with fireproof material (not included).
27. Keep an ABC type fire extinguisher near the work area.
28. Never perform welding or cutting operations on closed pipes or containers,
as the possible internal fumes may cause an explosion.
29. Never perform welding or cutting operations on open pipes or containers
that may have come in contact with moisture,chemicals, or flammable mate-
rials. Always clean and dry the areas first.
30. Welding and cutting fumes and gases may be hazardous if inhaled for long
periods of time.
31. Install a natural or forced-air ventilation system in the work area. If the venti-
lation system is inadequate, use an air respirator.
32. Use a forced-air ventilation system when welding or cutting lead, beryllium,
cadmium,zinc,zinc-coated or painted materials. Always wear an air respirator.
33. When welding or cutting in small areas, the operator should be accompanied
by another person (standing near the enclosed work area) to observe acci-
dent prevention procedures.
34. Do not perform welding or cutting operations near chlorinated hydrocarbon
vapors produced by degreasing or painting. The heat generated by arc rays
can react to form phosgene, a highly toxic gas.
35. Irritation of the eyes, nose, and throat are symptoms of inadequate ventila-
tion. Take immediate steps to improve ventilation. Do not continue operations if
symptoms persist.
36. Electric shock can be fatal. Never touch exposed electrical parts.
37. Switch off and disconnect the power source (power plug) before installing
the Mini Arc Electrode.
38. Installation must be performed by a qualified technician. Installation proce-
duresmustcomply withthe NationalElectricCode,and allother relevantregulations.
39. When welding or cutting, be aware that high frequency radiation may be pro-
duced which can interfere with radio navigation, safety devices, computers,
and communications equipment. Before operating, have a qualified technician
check out that possibility.
40. Avoid InterferenceWith Electronic Equipment. Usepropergroundingand shield-
ing to minimize the possibility of interference. Keep all cables close together and
close to the ground. Locate the welding or cutting operation as far as possible from
sensitive electronic equipment, or have the electronic equipment shut down tempo-
rarily.
41. Performance of this Mini Arc Welder may vary depending on variations in

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local line voltage. Extension cord usage may also affect tool performance.
42. Welding and cutting operations are a source of radiation, noise, heat, and
noxious fumes. The protection of the operator and any spectators must be guar-
anteed with suitable safety devices and precautions. Never approach arc rays or
hot metal without protection. Failure to observe these standards during operation
could lead to serious health risks.
43. Use the right tool or attachment for the right job. Do notattempt toforce asmall
tool or attachment to do the work of a larger industrial tool or attachment. There are
certain applications for which this product was designed. It will do the job better
and more safely at the rate for which it was intended. Do not modify this product,
and do not use this product for a purpose for which it was not intended.
44. Replacement parts and accessories: When servicing, useonlyidentical replace-
ment parts. Only use accessories intended for use with this product.
45. WARNING! The brass components of this product contain lead, a chemical
knowntothe StateofCaliformia tocause birth defects (orotherreproductiveharm).
(California Health & Safety code 25249.5, et seq.)
46. WARNING! This product, when used for welding, cutting, and similar appli-
cations, produces chemicals known to the State of Califormia to cause cancer
and birth defects (or other reproductive harm).
(California Health & Safety code 25249.5, et seq.)
47. 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.
48. WARNING! The warnings, precautions, and instructions discussed in this
instruction manual cannot cover all possible conditions and situations that may
occur. It must be understood by the operator that common sense and caution are
factors which cannot be built into this product, but must be supplied by the operator.
49. Use eye and breathing protection. Always wear ANSI approved, arc shaded,
impact safety face shield.Always use a full face shield when arc welding.Wear an
ANSIapproveddustmask orrespiratorwhen workingaroundmetal, chemicaldusts,
fumes and mists.
REV 05/04

ASSEMBLY AND OPERATING INSTRUCTIONS
NOTE: For additional references to the parts listed in the following pages, refer to the
Assembly Diagram on page 15.
1. WARNING! Prior to performing any assembly procedures, make sure
the Power Cord of the Mini Arc Welder is unplugged from its electrical
outlet.
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2. Before use, ground the Body Grounding Connector (13) directly to an earth pipe
or grounding rod with a separate cable of appropriate size (not included).
IMPORTANT: Only a qualified, certified electrician should perform this
procedure.
3. Install an electrode (not included) into the Electrode Holder (7) by squeezing the
Holder while positioning the electrode at the desired angle.
(See Figure D, next page.)
4. Connect the Ground Clamp (8) to the workpiece or to a metal welding table
where the workpiece will be placed. (See Figure D.)
5. Plug the Power Cord (9) into the nearest 110 volt, grounded, electrical outlet.
6. Hold the Electrode Holder (7) away from all objects. Then, turn the Power Switch
(5) to its “ON” position. (See Figure D.)
7. To begin welding, position the electrode at about a 60 degree angle and touch
the tip of it to the workpiece. Once the arc is stable, move the electrode along
the workpiece and down as the welding process consumes the electrode. Re-
place the electrode as needed to complete the job. (See Figure D.)

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POWER
SWITCH
(5)
POWER
CORD/PLUG
(9)
ELECTRODE
HOLDER
(7)
ELECTRODE
(NOT INCLUDED)
WORKPIECE GROUND
CLAMP
(8)
FIGURE D
8. NOTE: The Mini Arc Welder is equipped with an automatic “Hot Start”. This
feature momentarily surges the current output, which makes starting the elec-
trode easier. Should the electrode stick to the workpiece, usually a quick twist of
the Electrode Holder (7) will break the electrode free. If the electrode is not
broken loose, shut down the Mini Arc Welder and physically remove the
electrode from the Electrode Holder and workpiece. CAUTION! The electrode
and metal are hot.
9. When the job is completed, turn the Power Switch (5) to its “OFF” position,
and unplug the Power Cord (9) from its electrical outlet. Then, remove the
Ground Clamp (8) from the workpiece or metal table. (See Figure D.)

TROUBLESHOOTING GUIDE
1. The Mini ArcWelder will not turn on.
A. Make sure the Power Cord (9) is plugged in.
B. Make sure the Welder has not overheated. Use in a cool, shaded area.
When the Mini Arc Welder overheats it will automatically shut down tem-
porarily. When this happens stop welding, but leave the Welder on until it
cools down. Then, you may continue welding.
C. If the Welder does not cool down as described above, check to see if the Fan
(3) is operating. If the Fan is operating, check the side panel vents to see if
anything is obstructing airflow from the Fan. If obstructions exist, remove
them and wait for the Welder to cool.
2. The Mini ArcWelder is turned on, but will not strike an arc.
A. Make sure the electrode is securely attached to the Electrode Holder (7).
B. Make sure the Ground Clamp (8) is securely attached to the workpiece or
metal table on which the workpiece is placed, and that the point of attach-
ment is clean from rust, paint, or any other material that would insulate the
connection.
3. The current output is unstable and unable to produce a smooth welding
bead.
A. Make sure the Power Cord (9) is properly connected to its electrical outlet.
B. Make sure the Ground Clamp (8) is securely attached to the workpiece or
metal table on which the workpiece is placed, and that the point of attach-
ment is clean from rust, paint, or any other material that would insulate the
connection.
C. Make sure the electrode is in good condition. If not, replace the electrode.
INSPECTION, MAINTENANCE, AND CLEANING
1. WARNING! Make sure the Power Switch (5) is in its “OFF” position.
Unplug the Power Cord (9) from its electrical outlet, and allow the Mini Arc
Welder to completely cool before performing any inspection, maintenance, or
cleaning procedures.
2. Before each use, inspect the general condition of the Mini Arc Welder. Check
for damaged electrical wiring, loose connections, cracked, burnt, or broken
parts, 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.
SKU 91220 PAGE 13

3. Before each use, clean or, if necessary, replace the electrode.
4. To clean, use a shop vacuum cleaner, or use compressed air.
5. When storing, make sure to store the Mini Arc Welder in a safe, clean, and dry
location.
PLEASE READTHE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS
LIST AND ASSEMBLY DIAGRAM IN THIS MANUAL AS A REFERENCE TOOL ONLY.
NEITHERTHE 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
DISTRIBUTOREXPRESSLYSTATESTHAT ALL REPAIRSANDPARTSREPLACEMENTS
SHOULD BE UNDERTAKEN BY CERTIFIED AND LICENSEDTECHNICIANS, AND NOT
BYTHE 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.
SKU 91220 PAGE 14
Part # Description Qty. Part # Description Qty.
1 Machine Box 1 11 Flat Washer 8
2 Shell 1 12 Round Cross Head Screw 4
3 Self-Tapping Screw 12 13 Body Grounding Connector 1
4 Main Transformer 1 14 Grounding Connector Screw 1
5 Power Switch 1 15 Grounding Connector Washer 1
6 Lock Stud 3 16 Grounding Connector Nut 1
7 Electrode Holder 1 17 Nut (M6) 4
8 Ground Clamp 1 18 Flat Washer 4
9 Power Cord/Plug 1 19 Round Head Cross Screw 4
10 Foot 4
PARTS LIST

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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.

SCHEMATIC DIAGRAM
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