Hello Bill, Good luck in this years class. I think those welds started looking pretty good there bud. Yet like one of the guys said a lot of welding on such a small piece will change how the welding goes as far as heat penetration is.

The crater is an area where I have seen many cracks develop from in aluminum. What I like to do is when coming to end of weld , yes a little lighter on pedal, easing the amps down a bit, but I will then break the contact for just a second or two and then restart and add filler there by filling any would be crater.