Chicago Electric MIG-100 94056 Installation manual

90 AMP FLUX WIRE WELDER
94056
SET UP AND OPERATING INSTRUCTIONS
Distributed exclusively by Harbor Freight Tools®.
3491 Mission Oaks Blvd., Camarillo, CA 93011
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©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. 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.
REV 06g, 09e, 09h

Page 2For technical questions, please call 1-800-444-3353.SKU 94056
SAVE THIS MANUAL
You will need the manual for
the safety warnings and precautions,
assembly instructions, operating and
maintenance procedures, parts list and
diagram. Keep your invoice with this
manual. Write the invoice number on the
inside of the front cover. Keep the manual
and invoice in a safe and dry place for
future reference.
SAFETY WARNINGS AND
PRECAUTIONS
WARNING: When using tool, basic
safety precautions should always
be followed to reduce the risk of
personal injury and damage to
equipment.
Read all instructions before using this
tool!
Keep work area clean1. . Cluttered
areas invite injuries.
Observe work area conditions2. . Do
not use machines or power tools in
damp or wet locations. Don’t expose
to rain. Keep work area well lighted.
Do not use electrically powered tools
in the presence of ammable gases
or liquids.
Keep children away3. . Children must
never be allowed in the work area.
Do not let them handle machines,
tools, or extension cords.
Store idle equipment4. . When not
in use, tools must be stored in a dry
location to inhibit rust. Always lock
up tools and keep out of reach of
children.
Do not force tool5. . It will do the job
better and more safely at the rate
REV 06l
SPECIFICATIONS
Welding Current
.8 mm wire on 16 ga.
sheet steel
104.3/95.5 A
(Max/Min Setting)
.8 mm wire on 1/4”
steel plate
103.7/103.1 A
(Max/Min Setting)
Duty Cycle 10% @ 90 Amps (Max Setting) or
10% @ 80 Amps (Min Setting, actual 11%)
Power Consumption 120 V~, 24 A
Ground Cable 4 AWG, single insulation, 6’
Torch Power Cable 8 AWG, single insulation, 6’
Thermal Overload Both settings:
10 min. shutdown, 3 min. back on with Light
Welder Tip 0.030”; Spare: Welder Tip 0.035”;
Will also accept a 0.023” welder tip (not included)
Wire Size 0.030” ux core wire (using 0.030” Welder Tip)
Wire Spool Size 4” diameter
Overall Dimensions 14-1/2” (L) x 7-7/8” (W) x 15-1/2” (H)
Weight 34.45 lb.
Accessories Spare Welder Tip (0.035”)
Note: Performance of this tool may vary depending on variations in local line voltage.
Extension cord usage may also affect tool performance.

Page 3For technical questions, please call 1-800-444-3353.SKU 94056
for which it was intended. Do not
use inappropriate attachments in an
attempt to exceed the tool capacity.
Use the right tool for the job6. . Do
not attempt to force a small tool or
attachment to do the work of a larger
industrial tool. There are certain
applications for which this tool was
designed. Do not modify this tool and
do not use this tool for a purpose for
which it was not intended.
Dress properly7. . Do not wear loose
clothing or jewelry as they can be
caught in moving parts. Protective,
electrically nonconductive clothes and
nonskid footwear are recommended
when working. Wear restrictive hair
covering to contain long hair.
Use eye and ear protection8. . Always
wear ANSI-approved, arc-shaded,
impact safety face shield. Always use
the full face shield when welding.
Wear a NIOSH-approved dust mask
or respirator when working around
metal, chemical dusts, fumes and
mists.
Do not overreach9. . Keep proper
footing and balance at all times. Do
not reach over or across running
machines.
Maintain tools with care10. . Keep
tools sharp and clean for better
and safer performance. Follow
instructions for lubricating and
changing accessories. Inspect tool
cords periodically and, if damaged,
have them repaired by an authorized
technician. The handles must be
kept clean, dry, and free from oil and
grease at all times.
Disconnect power11. . Unplug tool
when not in use.
Remove adjusting keys and12.
wrenches. Check that keys and
adjusting wrenches are removed
from the tool or machine work surface
before plugging it in.
Avoid unintentional starting13. . Be
sure the switch is in the Off position
when not in use and before plugging
in. Do not carry any tool with your
nger on the trigger, whether it is
plugged in or not.
Stay alert14. . Watch what you are
doing, use common sense. Do not
operate any tool when you are tired.
Check for damaged parts15. . Before
using any tool, any part that appears
damaged should be carefully checked
to determine that it will operate
properly and perform its intended
function. Check for alignment and
binding of moving parts; any broken
parts or mounting xtures; and any
other condition that may affect proper
operation. Any part that is damaged
should be properly repaired or
replaced by a qualied technician. Do
not use the tool if any switch does not
turn On and Off properly.
Guard against electric shock16. .
Prevent body contact with grounded
surfaces such as pipes, radiators,
ranges, and refrigerator enclosures.
Replacement parts and17.
accessories. When servicing, use
only identical replacement parts.
Use of any other parts will void the
warranty. Only use accessories
intended for use with this tool.
REV 06g

Page 4For technical questions, please call 1-800-444-3353.SKU 94056
Approved accessories are available
from Harbor Freight Tools.
Do not operate tool if under the18.
inuence of alcohol or drugs.
Read warning labels on prescriptions
to determine if your judgment or
reexes are impaired while taking
drugs. If there is any doubt, do not
operate the tool.
Maintenance19. . For your safety,
service and maintenance should be
performed regularly by a qualied
technician.
Use proper size and type20.
extension cord. If an extension cord
is required, it must be of the proper
size and type to supply the correct
current to the tool without heating
up. Otherwise, the extension cord
could melt and catch re, or cause
electrical damage to the tool. This
tool requires use of an extension cord
of 20 amps minimum capability (up
to 30 feet), with wire size rated at 12
AWG. Longer extension cords require
larger size wire. If you are using the
tool outdoors, use an extension cord
rated for outdoor use (signied by
“WA” on the jacket).
Avoid electrical shock21. . Do not
permit electrically live parts, cables,
or electrodes to contact skin, clothing,
or gloves. Protective clothing should
be hole-free, dry, and ANSI-approved.
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 secure. Do not
weld unless you are insulated from
ground and the work piece.
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.
Avoid breathing fumes or gases22. .
They can cause serious health
problems. Use an active ventilation
system directly above the welding
area. Keep your head out of the
fumes.
Avoid eye and body damage23. .
Welding rays and infrared radiation
can injure eyes and burn skin.
Wear ANSI-approved 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.

Page 5For technical questions, please call 1-800-444-3353.SKU 94056
Know proper welding practices24. .
Read and understand the
manufacturer’s instructions, as well
as your employer’s safety practices
for welding.
Connect only to a code approved25.
power source. Connect only to a
grounding power source conforming
to the National Electrical Code and
Local Codes.
Avoid re and explosion26. . Remove
ammable and explosive material
from at least 35 feet from the welding
site to prevent welding sparks or
molten 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 being burned27. . Always wear
ANSI-approved welding gear: leather
gloves, leather apron, and shoes.
WARNING: This product, when used28.
for welding, plasma cutting, soldering,
or similar applications, 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.)
The warnings, cautions, and29.
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.
UNPACKING
When unpacking, check to make sure
the item is intact and undamaged. If any
parts are missing or broken, please call
Harbor Freight Tools at 1-800-444-3353 as
soon as possible.
ASSEMBLY
Cover
Locking
Spring (8)
Cover (31)
Handle (30)
Wire
Reel (27)
1. Attach the Handle (30) to the Cover
(31) using screw (29) inserted from the
Handle top-rear.
Attach the Cover Locking Spring (8) to2.
the front of the Base Frame (14) using
the supplied self-tapping screw.

Page 6For technical questions, please call 1-800-444-3353.SKU 94056
DUTY CYCLE
Duty cycle is a welding equipment
specication, which denes the number of
minutes, within a 10-minute period, during
which a given welder can safely produce
a particular welding current. For example,
this 90 amp welder with a 10% duty cycle
must be rested for at least 9 minutes after
1 minute of continuous welding.
Failure to carefully observe
duty cycle limitations can easily over
stress a welder’s power generation
system contributing to premature
welder failure. Many welders do not
have internal protection systems
that prevent this sort of over stress
-- leaving the task to the owner or
operator.
OPERATION
This Welder is used to weld sheet
metal and light carbon steel.
Caution: Before welding, read and
understand all safety precautions and
warnings listed on pages 2 through 5.
Securely clamp the Ground Cable1.
Clamp (33) as close as possible to
the metal object to be welded, or
to the metal work bench where the
object is mounted and electrically
connected.
Set the switch on the control panel to2.
MIN or MAX, as appropriate.
Verify that the Power Switch is in the3.
OFF position, then plug the Welder
plug into a dedicated, 110 VAC, 20
amp line with delayed action type
circuit breaker or fuses.
If an extension cord is used, it must
have the following wire size: up to 30
feet, use 12 AWG size wire; 30 to 50
feet, use 10 AWG wire; Over 50 feet,
use 8 AWG wire.
CONTROLS
Switch (7) Power On / Off
Switch (7) Current Min. / Max.
Overload Indicator Light (22)
Wire Feed Speed Knob (9)
Torch (1) Cable
Ground Cable (33) Power Cord (32)
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Page 7For technical questions, please call 1-800-444-3353.SKU 94056
While holding the Torch Cable Clamp4.
with electrode wire clearly out of the
way of any grounded objects, turn the
Power Switch to the ON position.
Momentarily press the Torch switch5.
to test the wire feed speed. Adjust
the speed by turning the Wire Feed
Speed Knob (9).
Orient yourself on the area to be6.
welded, then place a face shield over
your eyes.
Warning: Never look at the ignited
arc without ANSI-approved,
arc-shaded, eye protection in a
full face shield. Permanent eye
damage or blindness can occur.
Skin burns can occur. Never
breathe welding fumes.
Press (and hold) the Torch button and7.
stroke the area to be welded with the
electrode wire to ignite the arc.
Never tap the electrode wire into the
welding surface to ignite the arc. This
damages its external coating on the
electrode which prevents oxygen
in the air from coming into contact
with the molten metal, causing it to
oxidize.
8. Once the arc is ignited, tilt the
electrode wire forward at an angle of
approximately 35°.
The wire feeds automatically at a
speed dependent on the Min. or Max.
current setting.
Note: If too much current is drawn from
the Welder, the Thermal Overload
protector will activate, the amber
indicator will light, and the Welder
will turn off until it cools down. If this
happens, turn the Power Switch to
the OFF position and wait about 3 ~ 5
minutes.
When the weld is complete, lift the9.
electrode wire clearly away from any
grounded object, set the face shield
down, turn toward the Welder, and
turn the Power Switch to the OFF
position.
Unplug the Power Cord from the10.
electrical outlet.

Page 8For technical questions, please call 1-800-444-3353.SKU 94056
MAINTENANCE
Caution: Before performing any
maintenance on the Welder, unplug
the Power Cord from the electrical
outlet.
Periodically remove the Right and1.
Left side panels (12 and 13), and
using compressed air, blow out all
dust from the interior.
Store in a clean and dry location.2.
Replacing the Wire Reel
When the wire on the Feed Reel is
used up, you will need to replace it as
follows.
Wire Sheath
Wire Feed
Knob (37a)
Wire Feed
Arm (36a)
1. Press on the Cover Locking Spring
(8), then lift the Cover (31) using
Handle (30) to expose the Wire Feed
Unit (23a).
Unscrew the Wing Nut (25) and2.
remove the Reel Locking Knob (26).
Remove the empty Wire Reel (27).3.
Wire Reel
Wire
Sheath
Wire
Unwind wire t
h
i
s
d
i
r
e
c
t
i
o
n
4. Place the new Wire Reel over the
shaft and onto the Reel Spring (24).
The wire on the reel should unwind
counterclockwise so that it comes off
the reel straight into the wire sheath,
as illustrated above.
Replace the Reel Locking Knob and5.
the Wing Nut. Tighten well.
Loosen the Wire Feed Knob (37a)6.
and swing it off the Wire Feed Arm
(36a) to remove tension.
If the end of the wire is crimped or7.
bent, cut it off. Guide at least 12
inches of wire into the Wire Sheath.
Swing the Wire Feed Knob (37a)8.
back onto the Wire Feed Arm (36a)
and tighten it until the spring starts to
compress.
9. Turn the Torch Handle Nozzle
counterclockwise and pull to remove.
Turn the Contact Tip10.
counterclockwise and remove.
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Page 9For technical questions, please call 1-800-444-3353.SKU 94056
Lay the Torch Sheath out in a straight11.
line so that the wire moves through it
easily.
Warning: The following steps require
applying power to the welder. Do not
touch anything with the Torch Handle
or an arc may be ignited.
Plug the Power Cord into its electrical12.
outlet, press the Current Switch to
Max., and turn the welder ON.
Lift the Torch Handle and continue13.
pressing the Trigger until the wire
feeds through two inches.
If the wire does not feed, view the
Wire Feed Unit and see if the wire
is being pushed. If it is not, turn the
welder OFF and tighten the Wire
Feed Knob (37a).
Turn the welder ON again and press14.
the Trigger.
Once the wire is exposed, turn the15.
welder OFF and unplug it.
Slide the Contact Tip over the wire16.
and screw it into Torch Handle.
Replace the Nozzle and cut off any17.
excess wire over two inches.
Secure the Cover.18.
PLEASE READ THE
FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR
HAS PROVIDED THE PARTS DIAGRAM IN
THIS MANUAL AS A REFERENCE TOOL
ONLY. NEITHER THE MANUFACTURER NOR
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.

Page 10For technical questions, please call 1-800-444-3353.SKU 94056
Part Description Qty.
1 Torch 1
2 Contact Tip 1
3 Nozzle 1
4 Liner 1
5 Fixing Pole (A) for Gun Body 1
6 Fixing Pole (B) for Gun Body 1
7 Switch 2
8 Cover Locking Spring 1
9 Knob 1
10 Nut 1
11 Speed Control Circuit Board 1
12 Right Side Panel 1
13 Left Side Panel 1
14 Base Frame 1
15 Foot 4
16 Washer 4
17 Screw, ST 4.2 x 13 4
18 Transformer Carriage 2
19 Thermostat 1
Part Description Qty.
20 Transformer 1
21 Middle Partition Board 1
22 Overload Indicator Lamp 1
23a Wire Feed Unit 1
24 Reel Spring 1
25 Wing Nut M6 1
26 Reel Locking Knob 1
27 Wire Reel 1
28 Reel Holder 1
29 Screw, ST 4.2 x 25 1
30 Handle 1
31 Cover 1
32 Power Cord 1
33 Ground Cable 1
34 Wire Feed Roller 1
35 Wire Feed Bearing 1
36a Wire Feed Arm 1
37a Wire Feed Knob 1
PARTS LIST AND DIAGRAMS
Parts list
Record Product’s Serial Number Here:
Note: If product has no serial number, record month and year of purchase instead.
Note: Some parts are listed and shown for illustration purposes only, and are not
available individually as replacement parts.
REV 09e