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OVERLOAD PROTECTION
OUTPUT OVERLOAD
The Handymig 170i is equipped with a circuit breaker which protects the machine from damage if a severe overload occurs. The circuit breaker button will extend out when tripped. The circuit breaker must be manual- ly reset.
THERMAL PROTECTION
The Handymig 170i has a rated output duty cycle of 30%. If the duty cycle is exceeded, a thermal protec- tor will shut off the output until the machine cools to a reasonable operating temperature. This is an auto- matic function of the Handymig 170i and does not require user intervention. The fan continues to run during cooling.
ELECTRONIC WIRE DRIVE MOTOR PROTECTION
The Handymig 170i has
LEARNING TO WELD
No one can learn to weld simply by reading about it. Skill comes only with practice. The following pages will help the inexperienced operator to understand welding and develop this skill. For more detailed infor- mation, order a copy of “New Lessons in Arc Welding” listed at the end of this manual.
WARNING
Fumes and slag generated from Innershield type electrodes recom- mended for use with this welding machine can be toxic.
•Avoid contact with eyes and skin.
•Do not take internally.
•Keep out of reach of children.
•Follow all safety precautions found in this operating manual.
THE ARC-WELDING CIRCUIT
The operator’s knowledge of arc welding must go beyond the arc itself. The operator must know how to control the arc, and this requires a knowledge of the welding circuit and the equipment that provides the electric current used in the arc. Figure B.7 illustrates the welding circuit for a typical welding machine. The circuit begins where the gun cable is attached to the welding machine. Current flows through the gun cable, gun, and contact tip, to the wire and across the arc. On the work side of the arc, current flows through the base metal to the work cable and back to the welding machine. This circuit must be complete for the current to flow.
This machine’s welding circuit has a voltage output of 33 volts DC maximum. This voltage is quite low and is only present when the gun triggers depressed.
To weld, the work clamp must be tightly connected to clean base metal. Remove paint, rust, dirt or oil as necessary and connect the work clamp as close as possible to the area you wish to weld. This helps pre- vent current from going through an unwanted path. Avoid allowing the welding circuit to pass through hinges, bearings, electronic components, or similar devices that can be damaged. See Figure B.8. Always disconnect electrical devices before welding upon them.
FIGURE B.8
Electronic Components
Hinges
Bearings
The gun and cable assembly is held by the operator who guides the automatically fed wire along the joint, maintaining a contact tip to work distance of about 3/8 to 1/2 inch (10 – 12 mm). This is called electrical stickout. This electrical stickout (ESO) must be prop- erly maintained by the operator. The electric arc is made in the gap between the work and the tip end of a small diameter wire. When the power source is properly set, the arc gap is maintained automatically.
Arc welding is a manual skill requiring a steady hand, good physical condition, and good eyesight. The operator controls the welding arc, and, therefore, the quality of the weld made.
Handymig 170i
