Adding pre-flow to spool gun

[Gadgeteer]

I discovered a short time ago that the problem with aluminum wire burn-back at startup when using my spool gun was due to not having sufficient Argon gas coverage upon initiation of the arc. I solved the problem by holding the trigger for a few seconds before starting to weld, so the gas could get through the hose to the gun’s tip. But, then I had to grab my side cutter, and snip the excess wire before I could start the weld. My modification allows me to trigger the gas solenoid without powering the wire drive motor. Thusly, I can, now, just grab the gun, cut the motor, and charge the hose with gas each time I want to initiate the weld.