Buffalo Tools HIT140 Quick reference guide

ITEM # HIT140
80A MIG Welder
Assembly & Operating Instructions
READ ALL INSTRUCTIONS AND WARNINGS BEFORE USING THIS PRODUCT.
This manual provides important information on proper operation & maintenance. Every effort has been made to
ensure the accuracy of this manual. These instructions are not meant to cover every possible condition and situation
that may occur. We reserve the right to change this product at any time without prior notice.
IF THERE IS ANY QUESTION ABOUT A CONDITION BEING SAFE OR UNSAFE, DO NOT OPERATE
THIS PRODUCT!
HAVE QUESTIONS OR PROBLEMS? CONTACT CUSTOMER SERVICE.
If you experience a problem or need parts for this product, visit our website http://www.buffalotools.com or call our
customer help line at 1-636-532-9888, Monday-Friday, 8 AM - 4 PM Central Time. A copy of the sales receipt is
required.
FOR CONSUMER USE ONLY – NOT FOR PROFESSIONAL USE.
KEEP THIS MANUAL, SALES RECEIPT & APPLICABLE WARRANTY FOR FUTURE REFERENCE

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RECOGNIZE SAFETY SYMBOLS, WORDS AND LABELS
What You Need to Know About Safety Instructions
Warning and Important Safety Instructions appearing in this manual are not meant to cover all possible conditions
and situations that may occur. Common sense, caution and care must be exercised when operating or cleaning
tools and equipment.
Always contact your dealer, distributor, service agent or manufacturer about problems or conditions you do not
understand.
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 an imminently hazardous situation
which, if not avoided, will result in death or serious
injury.
WARNING indicates a potentially hazardous situation
which, if not avoided, could result in death or serious
injury.
CAUTION indicates a potentially hazardous situation
which, if not avoided, may result in minor or moderate
injury.
CAUTION used without the safety alert symbol
indicates a potentially hazardous situation which, if not
avoided, may result in property damage.

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SAFETY
Welding is dangerous, and may cause damage to you and others, so wear protection when
cutting.
Professional training is needed before operating the machine.
!Always wear ANSI-approved eyewear and protective equipment while operating this unit.
!The operator must be qualified personnel with a valid "metal welding/cutting (OFC)
operations" operation certificate.
!Cut off power before maintenance or repair.
WARNING: Electric shock—may lead to serious injury or even death.
!Install earth device according to the application criteria.
!Never touch the live parts when skin bared or wearing wet gloves/clothes.
!Make sure that you are insulated from the ground and workpiece.
!Make sure that your working position is safe.
WARNING: Smoke & gas may be harmful to health.
!Keep the head away from smoke and gas to avoid inhalation of exhaust gas from welding.
!Keep the working environment in good ventilation, use exhaust or ventilation equipment when
welding.
Arc radiation—may damage eyes or burn skin.
!Wear suitable cutting masks and protective clothing to protect your eyes and body.
!Use suitable masks or screens to protect spectators from harm.
Improper operation may cause fire or explosion.
!Welding sparks may result in a fire, so please make sure no combustible materials nearby
and pay attention to fire hazard.
!Have a fire extinguisher nearby, and have a trained person to use it.
WARNING: Hot workpiece may cause severe scalding.
!Do not contact hot workpiece with bare hands.
!Cooling is needed during continuous use of the welding torch.
Magnetic fields affect cardiac pacemaker.
!Pacemaker users should be away from the welding spot before medical consultation.
Moving parts may lead to personal injury.
!Keep yourself away from moving parts such as fan.
!All doors, panels, covers and other protective devices should be closed during operation.

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HIT140 is a gas (use solid wire) & gasless (use flux wire) MIG and MMA welder.
Specifications
ITEM
HIT140
Power voltage (v)
120
Frequency (HZ)
60
Max no load voltage output (V)
62
Output current (A)
MIG 30-80A/MMA 20-70A
Duty cycle
MIG 80A@30% / MMA 70A@30%
Suitable wire dia. (INCH)
Suitable electrode size (INCH)
MIG.030 - .035”
MMA 1-6-2.0MM
1/16" - 5/64"
Insulation class
F
Protection class
IP21S
Suggested Wire: Solid and Flux Cored Wire
Use with Gas or Without Shielding Gas
Welds Carbon Steel Between 1.2mm-3.0mm
Overload & Thermal Protection
Includes Welding Cable & Electrode Holder, MIG Torch, Grounding Cable & Earth Clamp, Wire Spool,
Clipping Hammer / Brush & Welding Face Shield
Welding Material: Carbon Steel, Stainless Steel, Aluminum, etc.

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Assembly
B (FOR GASLESS WELDING)

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C (FOR GAS WELDING )
D (FOR MMA WELDING )

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CAUTION ! ! ! !
1. WORKING ENVIRONMENT
1）BEST TO WORK IN DRY PLACES, NOT TOO WET OR RAINY OR FULL OF DUST ETC.
2）KEEP TEMPERATURE BETWEEN 14°F TO 140°F.
2. SAFETY
1）Please keep the machine cool, make sure the fan is working and not blocked.
2）The working voltage is AC 120V±15%, if lower or higher than this, it will cause damage.
3）The welder will automatic recover and work again when cooled down.
3. USE CORRECT CONSUMABLES
During welding, the working temperature is very hot and will cause the head of torch to be easily damaged. Please
change often.
Installation
1. Power requirement
AC single phase 120v (110-120V), 60HZ with a 20 amp time delayed fuse or circuit breaker is required.
DO NOT OPERATE THIS UNIT if the ACTUAL power source voltage is less than 105 volts AC or greater than
132 volts AC.
• High voltage danger from power source! Consult a qualified electrician for proper installation of receptacle. This
welder must be grounded while in use to protect the operator from electrical shock.
• Do not remove grounding prong or alter the plug in any way. Do not use any adapters between the welder’s
power cord and the power source receptacle. Make sure the POWER switch is OFF when connecting your
welder’s power cord to a properly grounded 120Vac, 60Hz, single phase, 20 amp power source.
2. Extension cord
It is strongly recommended that an extension cord should not be used because of the voltage drop it produces.
This drop in voltage can affect the performance of the welder. If you need to use an extension cord it must be a

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#2
#12 gauge cord or larger. Do not use an extension cord over 25 ft. in length.
3. Install the wire roller
Before installing any welding wire into the unit, the proper sized groove must be placed into position on the wire
drive mechanism. Adjust the drive roller according to the following steps, see following picture of the wire feed
mechanism:
3.1. Open the door to the welder drive compartment.
3.2. (see #1) Loosen the tension adjusting wing nut and lifting the Drive Tension Adjustor away from the Drive
Tension Arm (see #2). Pull the drive tension arm away from the wire roller.
3.3. If there is wire already installed in the welder, roll it back onto the wire spool by hand-turning the spool
counterclockwise. Be careful not to allow the wire to come out of the rear end of the inlet guide tube without holding
onto it or it will unspool itself. Put the end of the wire into the hole on the outside edge of the wire spool and bend it
over to hold the wire in place. Remove the spool of wire from the spool hub by removing the drive tensioning wing
nut and hardware.
3.4. Open the machine door using the “L” type six angle wrench, counterclockwise unscrewing the screw drive
roller on the wire, and remove the drive roller.

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3.5 Based on the wire diameter, select the correct groove using the following table:
Wire Diameter
Roller Groove
.030 inch
0.8
.035 inch
0.9
The drive roller has two wire size grooves. When installing the drive roller, the number stamped on the drive roller
for the wire size you are using should face in. This identifies the inside groove the wire will line up with. Assemble
the drive roller onto the drive roller shaft
4. Install the wire
4.1 Selecting the wire
Available wire for this machine
Wire Type
Available
MIG wire
.023 inch
Yes
MIG wire
.030 inch
Yes
Flux core
wire .030 inch
Yes
Flux core
wire .035 inch
Yes
MIG wires available are: mild steel, stainless steel or aluminum solid wire and must be used with shielding gas.
Four inch spools are available.
NOTE:
• Burn through will occur if you attempt to weld mild or stainless steel thinner than 24 gauge.
• Remove all rusted wire, if the whole spool is rusty discard it.
4.2 Install the wire
Electric shock can kill! Always unplug the power cord from the AC power source before installing wire.

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NOTE:
• Before installing, make sure that you have removed any old wire from the torch and cable assembly. This will help
to prevent the possibility of the wire jamming inside the Gun Liner.
• Be careful when removing the welding nozzle. The contact tip on this welder is live when the gun trigger is pulled.
Make certain POWER is turned OFF.
4.2.1 Remove the nozzle and contact tip from the end of the gun assembly. See following images for reference
4.2.2 Make sure the proper groove on the drive roller is in place for the wire to be installed. If not, change the drive
roller as described above.
4.2.3 Remove the packaging from the spool of wire and then identify the leading end of the wire secured in a hole
on the edge of the spool. DO NOT UNHOOK IT AT THIS TIME.
4.2.4 Place the spool on the spool hub with the wire coming off the bottom of the spool. The bottom of the spool
aligns with inlet to the drive system for smooth flow of the wire. See following figure.
4.2.5 The welder can use 4 inch spools only. The wing nut controls the tension on the spool.
4.2.6.
Setting the wire spool tension:
a) Turn the spool of wire with one hand.
b) Increase the spool tension by tightening (turn clockwise) the wing nut while
turning the spool. Turn the spool while tightening the wing nut until the spool
slows down and operator feels a slight drag.
Stop tightening the wing nut, operator may need to repeat these steps until proper
spool tension is achieved.
NOTE:
If TOO MUCH tension is applied to the wire spool, the wire will slip on the drive roller or will not be able to feed at
all. If TOO LITTLE tension is applied, the spool of wire will want to unspool itself when the trigger is released.
Wing nut

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Readjust the spool tension using the wing nut as necessary to correct for either problem.
4.2.7.After checking to make sure that your welder is disconnected from the AC power source, free the leading end
of the wire from the spool, but DO NOT LET GO OF IT until it is secure in the drive system or the wire will unspool
itself.
4.2.8. Using a wire cutter, cut the bent end off the leading end of the wire so that only a straight leading end
remains.
4.2.9. Loosen the tension adjusting knob holding the drive tension arm in place and lift the tension arm up off the
drive roller.
4.2.10. Insert the leading end of the wire into the inlet guide tube. Then push it across the drive roller and into the
MIG gun/torch assembly about six inches.
• Make certain that the welding wire is actually going into the torch liner. If not, the wire will jam in the mechanism.
4.2.11 Be sure the wire lines up in the groove of the drive roller then place the drive tension arm back in place
above the drive roller.
4.2.12 Position the quick release drive tension back up into position into the drive tension arm.
4.2.13 Tighten (turn clockwise) the drive tension adjusting knob until the tension roller is applying enough force on
the wire to prevent it from slipping out of the drive assembly. Do not over tighten.
4.2.14. NOW YOU CAN LET GO OF THE WIRE.
4.2.15. Plug in and turn the welder ON. Set the VOLTAGE switch to the voltage (heat) setting recommended for
the gauge metal that is to be welded. Refer to the set up chart on the inside of the wire feed compartment door.
4.2.16. Set the WIRE SPEED control in the middle of the wire speed range.
8.17. Straighten the MIG gun cable, pull the trigger on the welding torch to feed the wire through the torch
assembly. When at least one inch of the wire sticks out past the end of the torch, release the trigger.
4.2.18 Turn the Power Switch to the OFF position.
4.2.19 Select a contact tip stamped with the same diameter as the wire being used.
NOTE:
Due to inherent variances in flux-cored welding wire, it may be necessary to use a contact tip one size larger than
your flux core wire if wire jams occur.
4.2.20. Slide the contact tip over the wire (protruding from the end of the gun). Thread the contact tip into the end of
the gun adaptor and tighten securely.
4.2.21. Install the nozzle on the gun assembly. To keep spatter from sticking to inside of the nozzle use
anti-spatter spray or gel.
4.2.22 Cut off the excess wire that extends more than ¼” past the end of the nozzle.
4.2.23. Turn the welder ON
8” wire
spool

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5. Setting the wire tension
Arc flash can injure eyes! To reduce the risk of arc flash, make certain that the wire coming out of the end of the
torch does not come in contact with work piece, ground clamp or any grounded material during the drive tension
setting process or arcing will occur.
5.1. Press the trigger on the torch.
5.2. Turn the drive tension adjustment knob clockwise, increasing the drive tension until the wire seems to feed
smoothly without slipping.
6. Gas installation
Shielding gas cylinders and high pressure cylinders can explode if damaged, so treat them carefully.
-Never expose cylinders to high heat, sparks, open flames, mechanical shocks or arcs.
-Do not touch cylinder with MIG gun.
-Do not weld on the cylinder.
-Always secure cylinder upright to a cart or stationary object.
-Keep cylinders away from welding or electrical circuits.
-Use the proper regulators, gas hose and fittings for the specific application.
When MIG wire is used, shielding gas is required.
1. Polarity changing:
See page 5 for instructions.

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2. The gas hose, regulator and gas cylinder connections
Connect the gas hose to the gas solenoid valve on the back panel of the welder. Connect the other end to the
regulator connected to the shielding gas cylinder. See the following illustration.
3
2
1
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Cylinder valve: Controls GAS CYLINDER flow.
1. Cylinder pressure gauge
2. Gas flow gauge, set at 20 CFM
3. Regulator
4. Adjustment knob: Controls gas flow to the welder.
5. Gas hose
6. Gas cylinder
NOTE:
Slowly open the cylinder valve by turning it counterclockwise until the cylinder pressure gauge registers the
cylinder pressure. Turn the adjustment knob clockwise slowly to increase gas flow to 20 CFM. To reduce the gas
flow turn the adjustment counterclockwise. The gas solenoid valve is on the back panel of the welder. Gas flow
can be heard at the end of the gun when the trigger is activated. No gas flow will result in a harsh arc with
excessive spatter, a smooth weld bead will not be obtained.
3. Gas Selection
Different materials require different shielding gas when MIG welding, refer to the set up chart inside the wire feed
compartment also.
Mild steel: Use 75% Argon and 25% for reduced spatter and reduced penetration for thinner materials.
Do NOT USE Argon gas concentrations higher than 75% on steel. The result will be extremely poor penetration,
porosity, and brittleness of weld.
Mild Steel: Use CO2 for deeper penetration but increased spatter.
Stainless steel: Use a mixed gas consisting of Helium, Argon and CO2.
Aluminum or bronze: Use 100% Argon

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Operation*
High voltage danger from power source! Consult a qualified electrician for proper installation of receptacle at the
power source. This welder must be grounded while in use to protect the operator from electrical shock. If you are
not sure if your outlet is properly grounded, have it checked by a qualified electrician. Do not cut off the grounding
prong or alter the plug in any way and do not use any adapters between the welder’s power cord and the power
source receptacle. Connect your welder’s power cord to a properly grounded 120 VAC (110v-120v), 60Hz, single
phase, 20 amp power source.
1. Main Control Component
Power Knob - The power knob supplies electrical current to the welder. One knob controls the wire feed, output
current and output voltage.
2. Hold the MIG gun
The best way to hold the MIG gun is the way that feels most comfortable to you. While practicing to use your new
welder, experiment holding the torch in different positions until you find the one that seems to work best for you.
3. Position the MIG gun to the work piece
There are two angles of the MIG gun nozzle in relation to the work piece that must be considered when welding.
3.1. Angle A can be varied, but in most cases the optimum angle will be 60 degrees, the point at which the MIG gun
handle is parallel to the work piece. If angle A is increased, penetration will increase. If angle A is decreased,
penetration will decrease also.
3.2. Angle B can be varied for two reasons: to improve the ability to see the arc in relation to the weld puddle and to
direct the force of the arc.

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4. Distance from the work piece
If the nozzle is held off the work piece, the distance between the nozzle and the work piece should be kept
constant and should not exceed 1/4 inch or the arc may begin sputtering, signaling a loss in welding performance.
5. Tuning in the wire speed
This is one of the most important parts of MIG welder operation and must be done before starting each welding
job or whenever any of the following variables are changed: wire diameter, or wire type.
EXPOSURE TO A WELDING ARC IS EXTREMELY HARMFUL TO THE EYES AND SKIN!
Prolonged exposure to the welding arc can cause blindness and burns. Never strike an arc or begin welding until
you are adequately protected. Wear flameproof welding gloves, a heavy long sleeved shirt, trousers with out cuffs,
high topped shoes, and an ANSI approved welding helmet.
5.1. Connect the Ground Clamp to a scrap piece of the same type of material which you will be welding. It should
be equal to or greater than the thickness of the actual work piece, and free of oil, paint, rust, etc.
5.2. Hold the torch in one hand, allowing the nozzle to rest on the edge of the work piece farthest away from you,
and at an angle similar to that which will be used when welding. (See HOLDING THE TORCH if you are uncertain
of the angle at which you will be welding).
5.3. With your free hand, turn the Wire Speed Dial to maximum and continue to hold onto the knob.
5.4. Lower your welding helmet and pull the trigger on the torch to start an arc, then begin to drag the torch toward
you while simultaneously turning the Wire Speed Dial counter-clockwise.
5.5. LISTEN! As you decrease the wire speed, the sound that the arc makes will change from a sputtering to a
high-pitched buzzing sound and then will begin sputtering again if you decrease the wire speed too much. The
point on the wire speed adjustment where the high-pitched buzzing sound is achieved is the correct setting. You
can use the wire speed control to slightly increase or decrease the heat and penetration for a given heat setting by
selecting higher or lower wire speed settings. Repeat this tune-in procedure if you select a new heat setting, a
different diameter wire, or a different type of welding wire.
6. Welding Techniques
EXPOSURE TO A WELDING ARC IS EXTREMELY HARMFUL TO THE EYES AND SKIN! Prolonged exposure
to the welding arc can cause blindness and burns. Never strike an arc or begin welding until you are adequately
protected. Wear flameproof welding gloves, a heavy long sleeved shirt, trousers with out cuffs, high topped shoes

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and an ANSI approved welding helmet.
ELECTRIC SHOCK CAN KILL! To prevent ELECTRIC SHOCK, do not perform any welding while standing,
kneeling, or lying directly on the grounded work.
6.1 Moving the torch
Torch travel refers to the movement of the torch along the weld joint and is broken into two elements: Direction and
Speed. A solid weld bead requires that the welding torch be moved steadily and at the right speed along the weld
joint. Moving the torch too fast, too slow, or erratically will prevent proper fusion or create a lumpy, uneven bead.
Travel direction is the direction the torch is moved along the weld joint in relation to the weld puddle. The torch is
either PUSHED into the weld puddle or PULLED away from the weld puddle.
For most welding jobs you will pull the torch along the weld joint to take advantage of the greater weld puddle
visibility.
Travel speed is the rate at which the torch is being pushed or pulled along the weld joint. For a fixed heat setting,
the faster the travel speed, the lower
the penetration and the lower and narrower the finished weld bead. Likewise, the slower the travel speed, the
deeper the penetration and the higher and wider the finished weld bead.
6.2 Types of welding beads
As you become more familiar with your new welder and better at laying some simple weld beads, you can begin to
try some different weld bead types.
The STRINGER BEAD is formed by traveling with the torch in a straight line while keeping the wire and nozzle
centered over the weld joint. see following figure
The WEAVE BEAD Used when you want to deposit metal over a wider space than would be possible with a
stringer bead. It is made by weaving from side to side while moving with the torch. It is best to hesitate momentarily
at each side before weaving back the other way.
6.3 Welding position
FLAT POSITION Is easiest of the welding positions and is most commonly used. It is best if you can weld in the flat

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position if at all possible as good results are easier to achieve.
HORIZONTAL POSITION Is performed very much the same as the flat weld except that angle B (see HOLDING
THE TORCH) is such that the wire, directed more toward the metal above the weld joint is to help prevent the weld
puddle from running downward while still allowing slow enough travel speed. A good starting point for angle B is
about 30 degrees DOWN from being perpendicular to the work piece.
VERTICAL POSITION Is easier for many people to Pull the torch from top to bottom. It can be difficult to prevent
the puddle from running downward. Pushing the torch from bottom to top may provide better puddle control and
allow slower rates of travel speed to achieve deeper penetration. When vertical welding, angle B (see HOLDING
THE TORCH) is usually always kept at zero, but angle A will generally range from 45 to 60 degrees to provide
better puddle control.
OVERHEAD POSITION Is the most difficult welding position. Angle A (see HOLDING THE TORCH) should be
maintained at 60 degrees. Maintaining this angle will reduce the chances of molten metal falling into the nozzle.
Angle B should be held at zero degrees so that the wire is aiming directly into the weld joint. If you experience
excessive dripping of the weld puddle, select a lower heat setting. Also, the weave bead tends to work better than
the stringer.
6.4 Multiple pass welding
Butt Weld Joints When butt welding thicker materials, you will need to prepare the edges of the material to be
joined by grinding a bevel on the edge of one or both pieces of the metal being joined. When this is done, a “V” is
created between the two pieces of metal, that will have to be welded closed. In most cases more than one pass or
bead will need to be laid into the joint to close the “V”.
Laying more than one bead into the same weld joint is known as a multiple-pass weld.
The illustrations in following figure show the sequence for laying multiple pass beads into a single “V” butt joint.

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NOTE:
WHEN USING SELF-SHIELDING FLUX-CORE WIRE it is very important to thoroughly chip and brush the slag off
each completed weld bead before making another pass or the next pass will be of poor quality.
Fillet Weld Joints. Most fillet weld joints, on metals of moderate to heavy thickness, will require multiple pass
welds to produce strong joint. The illustrations in Figure 19 show the sequence of laying multiple pass beads into a
T fillet joint and a lap fillet joint.
6.5 Spot welding
There are three methods of spot welding: Burn-Through, Punch and Fill, and Lap. Each has advantages and
disadvantages depending on the specific application as well as personal preference.
1. The BURN-THROUGH METHOD welds two overlapped pieces of metal together by burning through the top
piece and into the bottom piece. With the burn-through method, larger wire diameters tend to work better than
smaller diameters. Wire diameters that tend to work best, with the burn-through method are .035 inch self-shielding
flux-core wire. Do not use .030 inch self-shielding flux core wires when using the burn-through method unless the
metal is VERY thin or excessive filler metal build-up and minimal penetration is acceptable. Always select the
HIGH heat setting with the burn-through method and tune in the wire speed prior to making a spot weld.
2. The PUNCH AND FILL METHOD produces a weld with the most finished appearance of the three spot
weld methods. In this method, a hole is punched or drilled into the top piece of metal and the arc is directed
through the hole to penetrate into the bottom piece. The puddle is allowed to fill up the hole leaving a spot weld that
is smooth and flush with the surface of the top piece. Select the wire diameter, heat setting, and tune in the wire
speed as if you were welding the same thickness material with a continuous bead.

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3. The LAP SPOT METHOD directs the welding arc to penetrate the bottom and top pieces, at the same time, right
along each side of the lap joint seam. Select the wire diameter, heat setting, and tune in the wire speed as if you
were welding the same thickness material with a continuous bead.
6.6 SPOT WELDING INSTRUCTIONS
1. Select the wire diameter and heat setting recommended above for the method of spot welding you intend to use.
2. Tune in the wire speed as if you were going to make a continuous weld.
3. Hold the nozzle piece completely perpendicular to and about 1/4 inch off the work piece.
4. Pull the trigger on the torch and release it when it appears that the desired penetration has been made.
5. Make practice spot welds on scrap metal, varying the length of time you hold the trigger, until a desired spot
weld is made.
6. Make spot welds on the actual work piece at desired locations.
Maintenance
The welder needs the regular maintenance as following:
Periodically clean dust, dirt, grease, etc. from your welder. Every six months, or as necessary, remove the cover
panel from the welder and air-blow any dust and dirt that may have accumulated inside the welder.
TROUBLESHOOTING

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Problem
Correction
1. The wire feeder is not working, no wire
coming out from the MIG torch
1. Please check the roller if it is running.
2. Please put the wire deep inside the MIG torch, then push the trigger
again.
2. The wire automatic coming out from the MIG
torch and non-stop, even push the button of
MIG torch
Electric board is broken (change board)
3. Whatever the wire feeder if working, there's
no wire coming from the MIG torch, even push
the button of MIG torch
First check the trigger of MIG torch, if trigger has a problem, please
change a new one;
If not OK , then check if the Electric board is broken (change board)
4. The machine is not working, OC light is on,
power is on, fan is working
Wait a few minutes, the machine may be over-heated. Allow it to cool
5. The wire feeding speed is not powerful and
slowly
The four -angles switch (on the wire feeder) is too tight, make it a little
loose