A good starting point is if you have a 1/8 rod its wire diameter Is .125 I set a machine to 125 and adjust accordingly to that. Every machine will be a bit different depending on a number of factors. Lead size and length, material being welded and even the manufactur of the rods being used. If you're using AC VS.DC things change as well. A good rule of thumb is diameter of the rod as your heat. 3/32 is .093 so your heat should be around that on a DC + machine and so on. I'm sure you will have to tweak it one way or the other.