Never Welded Aluminum before, got my New Combo Mig/Tig/Stick Welder a while back, still have to get the Spool Gun for doing Aluminum, but should be getting it soon. I want to add Material to the PTO Case for some Bosses for a Gear or Belt Drive like the 277 Case. I do plan to practic on a junk case before using a good one. 1. I was thinking of making a Dam around the Area using some Clay, or would I be better just Welding in some chunks of Aluminum to fill in the area. 2. Is it best to Heat part first in an Oven before Welding on it? What Temp if so?