I need to spot weld together 2 pieces of 16 gauge. Drilling a hole and welding it with the mig is getting old now that I need to make many of the same part. I have been looking at resistance spot welders but I am having a hard time finding information on the amps needed. I need to use 18 inch tongs with a 3/16 tip. I can ourchase a miller spot welder used locally that is sec. Amps 3600 with 18 inch tongs but I am not sure if that is enough. How can I figure out what size welder I need? Thanks