MIG WELDER - 250 AMP Model 91146 ASSEMBLY AND OPERATING INSTRUCTIONS ® 3491 Mission Oaks Blvd., Camarillo, CA 93011 Visit our Web site at: http://www.harborfreight.com 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. For technical questions, please call 1-800-444-3353.
PRODUCT SPECIFICATIONS Item Electrical Requirements Duty Cycles Maximum Welding Thickness Capacity Welding Current Required Wire Sizes Wire Control Settings Gun Coolant Type Fuse Type Gun Power Cable Length Ground Clamp Cable Length Wheels Accessories Weight Description Input Voltage: 220V / 60 Hz / 45 Input Amperage Power Cord: 10 AWG @ 6’ Long Power Plug: 220V (not included), Requires 50 Amp Circuit 60% @ 250 Amps / 100% @ 195 Amps Up To 3/8” Mild Steel 30 – 250 Amps .024” To .
. Keep bystanders, children, and visitors away while operating welding equipment. 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 1. Grounded welding equipment 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.
2. Dress properly. Do not wear loose clothing or jewelry. Contain long hair. Keep your hair, clothing, and gloves away from hot or moving parts. Loose clothes, jewelry, or long hair can be caught in hot or moving parts. (See page 8, number 3, for recommended safety clothing.) 3. Avoid accidental starting. Be sure the Power Switch is off before plugging in. Plugging in welding equipment with the Power Switch on invites accidents. 4.
8. Use only accessories that are recommended by the manufacturer for your model. Accessories that may be suitable for one type of welding equipment may become hazardous when used on another type of equipment SERVICE 1. Equipment service must be performed only by qualified repair personnel. Service or maintenance performed by unqualified personnel could result in a risk of injury. 2. When servicing welding equipment, use only identical replacement parts.
GROUNDING WARNING! Improperly connecting the grounding wire can result in the risk of electric shock. Check with a qualified 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.
EXTENSION CORDS The minimum extension cord size for this tool is 6 GAUGE for cords UP TO 25’ LONG. CORDS LONGER THAN 25’ SHOULD NOT BE USED WITH THIS WELDER. 1. Grounded welding equipment require a 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.
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 obstructions, grease, oil, trash, and other debris. Do not use the Welder in areas near flammable chemicals, dusts, and vapors. 2. Maintain labels and nameplates on the Welder. These carry important information. If unreadable or missing, contact Harbor Freight Tools for a replacement. 3. Prevent eye injury and burns.
7. When welding or cutting in small areas, the operator should be externally accompanied by another person (standing near the enclosed work area) to observe accident prevention procedures. 8. When welding or cutting, be aware that high frequency radiation may be produced which can interfere with radio navigation, safety devices, computers, and communications equipment. Before operating, have a qualified technician check out that possibility. 9. Keep high frequency source doors and panels tightly shut.
12. Industrial applications must follow OSHA requirements. 13. Never plug the Power Cord of this product into an electrical outlet while standing on a wet or damp surface. 14. 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 operating area will reduce their effectiveness and increase the danger of electric shock. 15.
25. Performance of this Welder may vary depending on variations in local line voltage. Extension cord usage may also affect tool performance. 26. Always turn off the Welder and unplug the unit from its electrical outlet before performing any inspection, maintenance, or cleaning procedures. 27. Use the right tool or attachment for the right job. Do not attempt to force a small tool or attachment to do the work of a larger industrial tool or attachment.
PRODUCT OVERVIEW 1. This Welder is designed for MIG/MAG welding on mild steel, stainless steel, and nonferrous materials up to 3/8” thickness. Additional features of this unit are as follows: (See Figure D.) A. Constant voltage transformer with step-up adjustment. B. Digital step-less electronic speed control. C. 2/4 Times, interval, and spot/pause welding. D. Pre-gas and post-gas flow. E. Soft start, burnback. F. Real-time digital volt-amp meter. G. Two inductance outlets (High & Low). H.
BACK PANEL CONTROLS 29 30 Part # Description Gas Inlet Valve Back Panel 29 30 FIGURE E PREGAS TIMER (5G) SOFT START (5F) BURN BACK TIMER (5E) POSTGAS TIMER (5D) INCHING BUTTON (36A) Part # 5D 5E 5F Description Post-Gas Timer Burn Back Timer Soft Start Potentiometer SIDE PANEL CONTROLS GAS TEST BUTTON (36B) Part # 5G 36A 36B Description Pre-Gas Timer Inching Button Gas Test Button FIGURE F SKU 91146 For technical questions, please call 1-800-444-3353.
ASSEMBLY INSTRUCTIONS NOTE: For additional references to the parts listed in the following pages, refer to the Assembly Diagrams on pages 26 and 28. To Attach A Power Cord Plug: 1. WARNING! Only a qualified, certified electrician should attach a 220 volt Power Plug (not included) to the Power Cord of the Welder. 2. For further instructions, refer to page 5 and page 6 of this manual. To Attach The Rear Wheels And Front Castor Wheels: 1.
To Attach The Gun Power Cable And Ground Clamp Cable: 1. Insert the plug of the Gun Power Cable (40A) firmly into the MIG Gun Outlet (2). (See Figure H.) 2. Insert the plug of the Ground Clamp Cable (201) firmly into the High Inductance Outlet (3A) or the Low Inductance Outlet (3B). NOTE: The High Inductance Outlet allows for a higher welding heat, resulting in a deeper penetration of the welding wire into thicker workpieces.
WIRE SPOOL (NOT INCLUDED) 4. (40A) (40A) 6” CONTACT TIP (90A) GAS NOZZLE (100A) SKU 91146 For technical questions, please call 1-800-444-3353.
6. Turn the Pressure Adjustment Knob clockwise to tighten the tension of the welding wire. NOTE: Use the Pressure Indicator Scale to set the desired drive roll pressure. (See Figure I.) 7. Remove the Gas Nozzle (100A) and Contact Tip (90A). (See Figure I.) 8. Turn the Power Switch (10) to its “ON” position. (See Figure I.) 9. Depress the Inching Button (36A) until the welding wire extends about 1” out of the Gun. Then, reinstall the Gas Nozzle (100A) and Contact Tip (90A). (See Figures F and I.) 10.
7. Adjust the flow rate of the gas by turning the Flow Adjust. The typical flow rate is 20 CFH (cubic feet per hour). Check the welding wire manufacturer’s recommended flow rate. (See Figure J.) PRESSURE REGULATOR FLOW METER (43) CYLINDER CAP CYLINDER VALVE ARGON GAS OR MIXED GAS GAS HOSE (202A) CHAIN GAS INLET VALVE (29) FIGURE J BACK PANEL (30) Welding Gun Duty Cycle And Overheating: 1.
The Four Welding Features: NOTE: The following four welding features are designed to optimize specific welding processes. (See Figure K.) 1. 2-TIME: Typically, the standard welding process used. To operate, turn the Wire Speed Mode Selector (6) to its 2-Time setting. Squeeze the Welding Gun Trigger (18A) to start the Pre-Gas. Then, weld accordingly. Release the Welding Gun Trigger to stop welding. The Post-Gas will continue to deliver the protective gas according to the setting of the Post-Gas Timer (5D).
.024” to .047” Hard or Flux Cored Wires 60% Duty Cycle at 250 Amperes Using Mixed Gases 6 Minutes Welding 4 Minutes Resting Relation Between Duty Cycle And Weld Amperes. 100 80 60 DUTY CYCLE (%) 40 20 FIGURE L 0 0 100 200 300 WELD AMPERES Relation Between Thickness, Diameter Of Wire, Wire Speed, Voltage, & Current*: FIGURE M *Do not change voltage while welding. Wire speed is a starting value only, and can be adjusted while welding.
Relation Between Wire Feed Speed, Size Of Wire, & Welding Current: FIGURE N TROUBLESHOOTING GUIDE - WELDING MACHINE Use larger welding leads. SKU 91146 For technical questions, please call 1-800-444-3353.
TROUBLESHOOTING GUIDE - WELDING GUN & WIRE DRIVE Problem No arc. Arc between gas nozzle and workpiece. Welding gun body or power cable overheated. Welding wire melted onto contact tip. Irregular wire feed. Possible Cause 1. Interruption of welding power circuit to welding gun or workpiece. 2. Power source or control defective. 3. Trigger wire broken, cut, or disconnected. 4. Power source contractor not activated. 1. Spatter build-up inside gas nozzle. 1. 2. 3. 4. 5. Welding current too high.
4. To replace the 3 AMP Buss Fuse: Failure of the Welder to operate may be caused by a blown 3 AMP Fuse (7) as indicated by its melted wire strand within the Fuse. To replace the Fuse, unscrew and remove the Fuse Cap. Remove the old Fuse, and install a new 3 AMP Fuse. Then, replace the Fuse Cap. 5. When storing, make sure to store the Welder in a safe, clean, dry location out of reach of children and unauthorized users. 6.
5. To replace the Gun Liner: Disconnect the Gun’s Power Cable from the Welding machine. Remove the Nozzle, Contact Tip, Adapter, Gas Diffuser, and Wire Outlet Guide. Then, remove the old Liner. Lay the Gun’s Power Cable out straight before installing a new Liner. Blow out the Gun Casing with compressed air. Install and tighten the new Liner. Cut Liner off 3/4” from the Head Tube (3/8” for aluminum). Then reinstall the Wire Outlet Guide, Gas Diffuser, Adapter, Contact Tip, and Nozzle. (See Figure P.
6. To clean exterior of Welding Gun: Use a damp cloth with a mild detergent. Then, dry. Do not use solvents to clean the Gun. 7. When storing: Make sure to store the Welding Gun in a safe, clean, and dry location out of reach of children and unauthorized users. 8. WARNING! All maintenance, service, and repairs not listed in this manual are only to be attempted by a qualified service technician.
PARTS LIST - WELDING MACHINE P a rt # 1 2 3A D e s c rip tio n F ro n t P a n e l M IG G u n O u tle t H ig h In d u c ta n c e O u tle t P a rt # 12 13 14 P a rt # 31 32 33 D e s c rip tio n C y lin d e r S u p p o rt Fan W ire S p o o l H u b 15 16 17 18 19 20 21 22 23 24 25 D e s c rip tio n D ig ita l V o lt/A M P D is p la y F ro n t P a n e l B ra c k e t D ig ita l W ire F e e d S p e e d D is p la y W e ld in g T ra n s fo rm e r M a g n e tic C o n tra c to r 8 -P in R e la y 8 -P in R e la y
PARTS LIST - WELDING GUN Part # 1A 4A 6A 7A 10A 18A 40A 40.1A 44A 45A 46A 54A 56A 57A 57.1A ------------- SKU 91146 Description Part # Swan Neck (MB 25 AK, 50° Bent) 58A Nozzle Spring 59A Gun Body, Brass 60A Gun Body, Plastic 61A Ergonomic Handle 62A Trigger 80A Power Cable (4.
ASSEMBLY DIAGRAM - WELDING GUN 201A: GROUND CLAMP CABLE NOT SHOWN. 202A: GAS HOSE NOT SHOWN. 4A 90A 80A 1A 100A 10A 7A 200A 18A 44A 45A 44A 45A 120A 40.1A 130A 131A 133A 132A 54A 56A 40.1A46A 58A 62A 54A 62A 57A 57.1A 59A 60A 61A 46A NOTE: Some parts are listed and shown for illustration purposes only, and are not available individually as replacement parts. SKU 91146 For technical questions, please call 1-800-444-3353.
ELECTRICAL SCHEMATIC - WELDING MACHINE SKU 91146 For technical questions, please call 1-800-444-3353.
