Chicago Electric 66787 Installation manual

240 VOLT ARC/TIG
INVERTER WELDER
AND TIG WELDING TORCH
Model 66787
SET UP AND OPERATING INSTRUCTIONS
Visit our website at: http://www.harborfreight.com
Read this material before using this product.
Failure to do so can result in serious injury.
SAVE THIS MANUAL.
Copyright©2009 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. Diagrams within this manual may not be drawn proportionally. Due to continuing
improvements, actual product may differ slightly from the product described herein. Tools required for
assembly and service may not be included.
For technical questions or replacement parts, please call 1-800-444-3353.
Revised Manual 09h, 09k, 09l

Page 2SKU 66787 For technical questions, please call 1-800-444-3353.
CONTENTS
IMPORTANT SAFETY INFORMATION............................................................................3
General Safety Rules...........................................................................................3
 SpecicSafetyRules...........................................................................................5
PRODUCT SPECIFICATIONS.........................................................................................9
UNPACKING....................................................................................................................9
TIG TORCH ASSEMBLY.................................................................................................9
WELDER FEATURES....................................................................................................10
OPERATING INSTRUCTIONS.......................................................................................11
Tool Set Up.........................................................................................................11
Work Piece and Work Area Set Up...................................................................11
General Operating Instructions.........................................................................11
TIG TORCH Operating Instructions...................................................................13
MAINTENANCE AND SERVICING................................................................................14
TROUBLESHOOTING...................................................................................................15
WELDER PARTS LIST AND ASSEMBLY DIAGRAM...................................................16
TIG TORCH PARTS LIST AND ASSEMBLY DIAGRAM...............................................17
PLEASE READ THE FOLLOWING CAREFULLY.........................................................17
PRODUCT WARRANTY INFORMATION......................................................................18

Page 3SKU 66787 For technical questions, please call 1-800-444-3353.
SAVE THIS MANUAL
Keep this manual for the safety warn-
ings and precautions, assembly, operating,
inspection, maintenance and cleaning pro-
cedures. Write the product’s serial number
in the back of the manual (or month and
year of purchase if product has no num-
ber). Keep this manual and the receipt in
a safe and dry place for future reference.
In this manual, on the labeling,
and all other information provid-
ed with this product:
This is the safety alert
symbol. It is used to alert
you to potential personal
injury hazards. Obey all
safety messages that
follow this symbol to avoid
possible injury or death.
DANGER indicates
a hazardous
situation which, if not
avoided, will result in death or
serious injury.
WARNING
indicates a
hazardous situation which, if
not avoided, could result in
death or serious injury.
CAUTION, used
with the safety
alert symbol, indicates a
hazardous situation which, if
not avoided, could result in
minor or moderate injury.
NOTICE is used to
address practices
not related to personal injury.
CAUTION, without
the safety alert
symbol, is used to address
practices not related to
personal injury.
General Safety Rules
WARNING! Read all instructions
Failure to follow all instructions
listed below may result in
electricshock,re,and/or
serious injury. The term “power
tool” in all of the warnings listed
below refers to your line-operated
(corded) ARC/TIG Inverter Welder.
SAVE THESE INSTRUCTIONS
Work area safety1.
Keep work area clean and well lit.a.
Cluttered or dark areas invite acci-
dents.
Do not operate power tools in ex-b.
plosive atmospheres, such as in
the presence of ammable liquids,
gases or dust. Power tools create
sparks which may ignite the dust or
fumes.
Keep children and bystanders awayc.
while operating a power tool. Dis-
tractions can cause you to lose
control.
Electrical safety2.
Avoid body contact with groundeda.
surfaces such as pipes, radiators,
ranges and refrigerators. There is
an increased risk of electric shock if
your body is grounded.
IMPORTANT SAFETY
INFORMATION

Page 4SKU 66787 For technical questions, please call 1-800-444-3353.
Do not expose power tools to rainb.
or wet conditions. Water entering a
power tool will increase the risk of
electric shock.
Do not abuse the cord. Never usec.
the cord for pulling or unplugging the
power tool. Keep cord away from
heat, oil, sharp edges or moving
parts. Damaged or entangled cords
increase the risk of electric shock.
When operating a power tool out-d.
doors, use an extension cord suit-
able for outdoor use. Use of a cord
suitable for outdoor use reduces the
risk of electric shock.
Personal safety3.
Stay alert, watch what you are do-a.
ing and use common sense when
operating a power tool. Do not use
a power tool while you are tired or
under the inuence of drugs, alcohol
or medication. A moment of inatten-
tion while operating power tools may
result in serious personal injury.
Use safety equipment. Always wearb.
eye protection. Safety equipment
such as arc shaded, impact safety
full face shield, dust mask or respi-
rator, heavy-duty work gloves, non-
skid safety shoes, or hearing protec-
tion used for appropriate conditions
will reduce personal injuries.
Avoid accidental starting. Ensurec.
the switch is in the off-position be-
fore plugging in. Carrying power
tools with your nger on the switch
or plugging in power tools that have
the switch on invites accidents.
Do not overreach. Keep proper foot-d.
ing and balance at all times. This
enables better control of the power
tool in unexpected situations.
Power tool use and care4.
Do not force the power tool. Use thea.
correct power tool for your applica-
tion. The correct power tool will do
the job better and safer at the rate
for which it was designed.
Do not use the power tool if theb.
switch does not turn it on and off.
Any power tool that cannot be con-
trolled with the switch is dangerous
and must be repaired.
Disconnect the plug from the powerc.
source before making any adjust-
ments, changing accessories, or
storing power tools. Such preventive
safety measures reduce the risk of
starting the power tool accidentally.
Store idle power tools out of thed.
reach of children and do not allow
persons unfamiliar with the power
tool or these instructions to oper-
ate the power tool. Power tools are
dangerous in the hands of untrained
users.
Maintain power tools. Check fore.
misalignment or binding of moving
parts, breakage of parts and any
other condition that may affect the
power tool’s operation. If damaged,
have the power tool repaired before
use. Many accidents are caused by
poorly maintained power tools.
Use the power tool and its acces-f.
sories in accordance with these
instructions and in the manner
intended for the particular type of
power tool, taking into account the
working conditions and the work to
be performed. Use of the power tool
for operations different from those
intended could result in a hazardous
situation.

Page 5SKU 66787 For technical questions, please call 1-800-444-3353.
Service5.
Have your power tool serviced bya.
a qualied repair person using only
identical replacement parts. This will
ensure that the safety of the power
tool is maintained.
SpecicSafetyRules
Maintain labels and nameplates on1.
the tool. These carry important safety
information. If unreadable or miss-
ing, contact Harbor Freight Tools for a
replacement.
Do not touch the tip of the Torch2.
when the welder is connected to
power. The Torch will immediately
activate when it is plugged in. The
operator must carefully direct the
torch whenever the welder is con-
nected to power. When the operator
is not holding the Torch, it must be
sitting on a nonconductive, nonam-
mable surface.
Feed the ller metal being used into 3.
the arc with a properly insulated
holder.
Avoid electrical shock. Do not per-4.
mit electrically live parts, cables, or
electrodes to contact skin, clothing, or
gloves. Wear ANSI-approved protec-
tive clothing. This unit draws enough
current to cause serious injury or
death. Before turning the Welder on,
check the electrode holder to be sure
that there are no protruding screw
heads, and that all insulation is se-
cure. Do not weld unless you are
insulated from ground and the work
piece.
Avoid eye and body damage. Arc5.
rays and infrared radiation can injure
eyes and burn skin. Wear ANSI ap-
proved eye and body protection. Do
not allow viewing by visitors without
proper eye and body protection. Use
a Face Shield with arc shaded lter
plate.
Move ammable and explosive mate-6.
rial at least 35 feet from the welding
arc to prevent welding sparks or mol-
ten metal from starting a re. Keep a
type ABC re extinguisher within easy
reach. Thoroughly clean the object
being welded of any paint, grease, or
other foreign material.
Avoid unintentional starting. Prepare7.
to begin work before turning on the
Welder.
Do not leave the Welder unattended8.
when it is plugged into an electrical
outlet. Turn off the tool, and unplug it
from its electrical outlet before leav-
ing.
Use clamps (not included) or other9.
practical ways to secure and support
the work piece to a stable platform.
Holding the work by hand or against
your body is unstable and may lead
to loss of control.
This product is not a toy. Keep it out10.
of reach of children.
Industrial applications must follow11.
OSHA guidelines.
People with pacemakers should12.
consult their physician(s) before use.
Electromagnetic elds in close prox-
imity to heart pacemaker could cause
pacemaker interference or pacemak-
er failure. In addition, people with
pacemakers should: Rev 09h

Page 6SKU 66787 For technical questions, please call 1-800-444-3353.
• Avoid operating alone.
• Do not use with power switch locked
on.
• Properly maintain and inspect to
avoid electrical shock.
• Any power cord must be properly
grounded. Ground Fault Circuit Inter-
rupter (GFCI) should also be imple-
mented – it prevents sustained elec-
trical shock.
WARNING: This product, when used13.
for welding, produces chemicals
known to the State of California to
cause cancer and birth defects (or
other reproductive harm). (California
Health & Safety Code § 25249.5, et
seq.)
14. Prevent eye injury and
burns. Wearing and using
ANSI-approved personal
safety clothing and safety
devices reduce the risk for
injury.
Wear ANSI-approved safety impact•
eye glasses underneath welding
eye protection featuring at least a
Number 10 shade lens rating.
Leather leggings, re resistant •
shoes or boots should be worn
when using this product. Do not
wear pants with cuffs, shirts with
open pockets, or any clothing that
can catch and hold molten metal or
sparks.
Keep clothing free of grease, oil,•
solvents, or any ammable sub-
stances. Wear dry, insulating gloves
and protective clothing.
Wear an approved head covering•
to protect the head and neck. Use
aprons, cape, sleeves, shoulder
covers, and bibs designed and
approved for welding and cutting
procedures.
When welding/cutting overhead•
or in conned spaces, wear ame
resistant ear plugs or ear muffs to
keep sparks out of ears.
15. Prevent accidental res.
Remove any combustible
material from the work
area.
When possible, move the work to a•
location well away from combustible
materials. If relocation is not pos-
sible, protect the combustibles with
a cover made of re resistant mate-
rial.
Remove or make safe all combus-•
tible materials for a radius of 35 feet
(10 meters) around the work area.
Use a re resistant material to cover
or block all open doorways, win-
dows, cracks, and other openings.
Enclose the work area with por-•
table re resistant screens. Protect
combustible walls, ceilings, oors,
etc., from sparks and heat with re
resistant covers.
If working on a metal wall, ceiling,•
etc., prevent ignition of combus-
tibles on the other side by moving
the combustibles to a safe loca-
tion. If relocation of combustibles
is not possible, designate someone
to serve as a re watch, equipped
with a re extinguisher, during the
cutting process and for at least one
half hour after the cutting is com-
pleted.
Do not weld or cut on materials•
having a combustible coating or
combustible internal structure, as
in walls or ceilings, without an ap-
Rev 09h

Page 7SKU 66787 For technical questions, please call 1-800-444-3353.
proved method for eliminating the
hazard.
Do not dispose of hot slag in con-•
tainers holding combustible materi-
als. Keep a re extinguisher nearby
and know how to use it.
After spot welding, make a thorough•
examination for evidence of re. Be
aware that easily-visible smoke or
ame may not be present for some
time after the re has started. Do
not weld or cut in atmospheres
containing dangerously reactive or
ammable gases, vapors, liquids,
and dust. Provide adequate ven-
tilation in work areas to prevent
accumulation of ammable gases,
vapors, and dust. Do not apply
heat to a container that has held an
unknown substance or a combus-
tible material whose contents, when
heated, can produce ammable or
explosive vapors. Clean and purge
containers before applying heat.
Vent closed containers, including
castings, before preheating, weld-
ing, or cutting.
Do not touch live electrical parts.16.
Wear dry, insulating gloves. Do not
touch electrode or conductor tong
with bare hand. Do not wear wet or
damaged gloves.
Protect yourself from electric shock.17.
Do not use outdoors. Insulate your-
self from the work piece and ground.
Use nonammable, dry insulating
material if possible, or use dry rubber
mats, dry wood or plywood, or other
dry insulating material big enough to
cover your full area of contact with
the work or ground.
Ensure that the unit is placed on a18.
stable location before use. If this unit
falls while plugged in, severe injury,
electric shock, or re may result.
Ground this product. This Welder19.
requires the attachment and use of
a UL-listed, 240 volt, grounded,
3-prong, electrical Power Cord
Plug (not included). Only a quali ed
electrician should install the Power
Cord Plug. Never remove the ground-
ing prong or modify the Power Cord
Plug in any way. Do not use adapter
plugs with this product.
Avoid overexposure to fumes and20.
gases. Always keep your head out
of the fumes. Do not breathe the
fumes. Use enough ventilation or
exhaust, or both, to keep fumes and
gases from your breathing zone and
general area.
Where ventilation is questionable,•
have a qualied technician take
an air sampling to determine the
need for corrective measures. Use
mechanical ventilation to improve
air quality. If engineering controls
are not feasible, use an approved
respirator.
Follow OSHA guidelines for Permis-•
sible Exposure Limits (PEL’s) for
various fumes and gases.
Follow the American Conference•
of Governmental Industrial Hygien-
ists recommendations for Threshold
Limit Values (TLV’s) for fumes and
gases.
Have a recognized specialist in•
Industrial Hygiene or Environmental
Services check the operation and
air quality and make recommenda-
Rev 09h

Page 8SKU 66787 For technical questions, please call 1-800-444-3353.
tions for the specic welding or cut-
ting situation.
WARNING: Handling the Power21.
Cord on this product will expose you
to lead, a chemical known to the
State of California to cause cancer,
birth defects, and other reproductive
harm. Wash hands after handling.
(California Health & Safety Code §
25249.5 et seq.)
WARNING
INHALATION HAZARD:
Welding and Plasma Cutting Produce
TOXIC FUMES.
Exposure to welding or cutting
exhaust fumes can increase the risk
of developing certain cancers, such as
cancer of the larynx and lung cancer.
Also, some diseases that may be linked
to exposure to welding or plasma cutting
exhaust fumes are:
• Early onset of Parkinson’s Disease
• Heart disease • Ulcers
• Damage to the reproductive organs
• Inammation of the small intestine or
stomach • Kidney damage
• Respiratory diseases such as
emphysema, bronchitis, or pneumonia
Use natural or forced air ventilation and
wear a respirator approved by NIOSH to
protect against the fumes produced to
reduce the risk of developing the above
illnesses.
23. The warnings, precautions, and in-
structions discussed in this instruction
manual cannot cover all possible con-
ditions 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.
SAVE THESE
INSTRUCTIONS.
REV 09e; 09h

Page 9SKU 66787 For technical questions, please call 1-800-444-3353.
SPECIFICATIONS
Electrical
Requirements
240V~ / 60 Hz / 25A max.
Power Cord: SJT 12AWG x 3C
Power Plug: 3-Prong, 240 VAC
(Not Included)
Output
Amperage
Range
10-130 Amps
Maximum
Open Circuit
Voltage
61V
Duty Cycle
40% @ 130 Amps
60% @ 120 Amps
100% @ 80 Amps
Maximum
Welding
Capacity
1/4” - For Welding Steel Only
Electrode
Diameter
Capacity
For Use With
1/16”, 3/32” and 1/8” Diameter
Rods
Electrode
Holder Head
Ground Cable
75”
65”
Torch Cable
Length 12’ 9”
Gas Hose 8’ 6” L, 0.34” OD, .19” ID
Additional
Features
May be used for both arc and tig
welding.
Quick starting with high open
voltage.
Anti-Stick circuit works with
rutile, basic steel, stainless
steel, and cast iron electrodes.
Additional amperage during
short arc length conditions
increases electrode penetration.
UNPACKING
When unpacking, check to make sure
that the item is intact and undamaged. 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.
Note: For TIG Welding Torch Parts
List and Diagram, refer to page 17.
REV 09h, 09l
When assembling Torch, make1.
sure Torch Cable is not connected
to Welder or argon gas supply.
Ceramic
Nozzle
(3a/3b)
Rod
Holder
(2a)
Gas Flow
Knob
Handle
(Front) (Back)
2. Thread either Rod Holder (2a) or Plug
(6a) securely into back of Torch (1a).
Choose a matching set of Collet and3.
Collet Holder, either 1/16” (4a & 5a)
or 3/32” (4b & 5b), depending on the
rod to be used. Insert the Collet, nar-
rower end rst, into the Collet Holder,
and then thread the Collet Holder
loosely into the front of the Torch.
Place a prepared tungsten welding4.
rod (the correct diameter for the Col-
let used) into Collet. Tighten Collet
Holder in place.
Attach desired Ceramic Nozzle (3a or5.
3b) onto Collet Holder. Do not over-
tighten. Ceramic Nozzles of larger
sizes will contain shielding gas in a
larger area, but may require more gas
ow to be effective.
Connect the gas hose securely to the6.
regulator on the argon bottle. Set the
argon regulator to 18-22 PSI. Fol-
low the gas cylinder manufacturer’s
instructions for set-up and use.
Connect the cable to the Welder.7.
Twist to lock in place.
TORCH ASSEMBLY

Page 10SKU 66787 For technical questions, please call 1-800-444-3353.
WELDER FEATURES
Electrode Holder (8):1. Connect the
Electrode Holder Cable to the POSI-
TIVE Terminal located at the front of
the Welder. (See Figure A.)
Ground Clamp (9):2. Connect the
Ground Clamp Cable to the NEGATIVE
Terminal located on the front of the
Welder. (See Figure A.)
Potentiometer Dial (4):3. Turn the Dial
clockwise or counterclockwise to regu-
late the welding current (from 10 to 130
amps). (See Figure B.)
Green “Power On” Light (5):4. When
illuminated, indicates the Welder is
receiving electrical power and is ready
for use. (See Figure B.)
Yellow “Overheating” Light (5):5.
When illuminated, indicates overheat-
ing caused by an excessively intense
duty cycle. In this case, stop welding
and wait until the welder has cooled
down. The welder will automatically
restart after the yellow “overheating”
light turns off.(See Figure B.)
Fan (14):6. The Fan must operate con-
tinuously when operating the Welder to
prevent the unit from overheating.
(See Figure C.)
Power Switch (16):7. The Power Switch
must illuminate before welding opera-
tions can begin.
(See Figure C.)
Tig Welder Torch8.
REV 09h