OPERATIONB-13

12.When no more welding is to be done, close valve on gas cylinder (if used), momentarily operate gun trigger to release gas pressure, and turn off SP-255.

SPOT WELD MODE

Arc spot plug welds are used when continuous welds are not needed or to hold thin sheet metal together prior to stitch welding or continuous welding. Plug welds are made by using a punch to make a 3/16 inch (4.8 mm) diameter hole in the top sheet and arc weld- ing through the hole into the back sheet.

Spot On Time sets welding time. Start with a dial set- ting of about 1.2 seconds.

To make an arc spot plug weld, punch 3/16 inch (4.8

mm)holes in top sheet. Set the procedure for the metal thickness to be welded. Install spot weld nozzle (if available) on gun and press it against the top sheet so the top and bottom sheets are tight together. Close trigger and hold it closed until the arc goes out. If a spot weld nozzle is not used, smoother welds will result by moving the welding wire in a small circle dur- ing the weld.

STITCH WELD MODE

Used to weld thin material where warpage and burn- through are a problem. Proper adjustment of ON and OFF times and arc travel speed permits welding thin sheet metal with small welds, minimum distortion, and no burnthrough.

Stitch On Time sets welding time. Start with a dial set- ting of 0.5 seconds. Raise setting to increase penetra- tion and weld size; lower setting to reduce burn- through and distortion.

Stitch Off Time sets off time. Start with a dial setting of 0.5 seconds. Raise setting to reduce burnthrough; lower setting to make weld flatter and smoother.

To weld, set the procedure for the metal thickness to be welded. Close trigger and hold it closed for length of seam. Hold gun in one place during ON time and move gun just beyond edge of molten metal during OFF time.

NOTE: For smoothest welds on thinner metal, point gun slightly toward direction of travel.

AVOIDING WIRE FEEDING

PROBLEMS

Wire feeding problems can be avoided by observing the following gun handling procedures:

a.Do not kink or pull cable around sharp corners.

b.Keep the electrode cable as straight as possible when welding or loading electrode through cable.

c.Do not allow dolly wheels or trunks to run over cables.

d.Keep cable clean by following maintenance instructions.

e.Use only clean, rust-free electrode. The Lincoln electrodes have proper surface lubrication.

f.Replace contact tip when the arc starts to become unstable or the contact tip end is fused or deformed.

g.Keep wire reel spindle brake tension to minimum required to prevent excess reel over-travel which may cause wire “loop-offs” from coil.

h.Use proper drive rolls and wire drive idle roll pres- sure for wire size and type being used. (See Drive Roll Kits in Accessories section.)

FAN CONTROL

The fan motor is thermostatically controlled to provide cooling for the transformer and other components only when required. Even though the power switch is on, the fan motor will not run when the machine does not require fan cooling, such as when first turned on, or when welding at low current or duty cycle proce- dures.

INPUT LINE VOLTAGE

PROTECTION

HIGH LINE VOLTAGE—If the line voltage exceeds 121% of rated input voltage, the output will be reduced to the lower level to protect voltage rating of the capacitor bank. A HIGH LINE message will be dis- played if the output has been reduced (see Section on Explanation of Prompting and Error Messages).

LOW LINE VOLTAGE—You may not be able to get maximum output from the machine if the line voltage is less than rated input. If the output you want is not obtainable because of insufficient line voltage, a LOW

IDEALARC SP-255