I sometimes use up odd pieces making boxes of aluminum. My garage has open studding I padded out to 11" deep. At 12" spacing shelving fits between made from 3/4" thick stock. It makes it easier to grab associated parts in one container and go. I usually weld from 16 gauge 6061 starting with outside corners, then reinforcing by doing inside. On those I grind the weld smooth, I sometimes find the outside corner weld has little penetration. With very deep boxes it is difficult to get down inside to do a inside corner. When in the grinding process I discover a crack, it is very challenging to fill it in.

Is there a trick to get deeper penetration on these outside corners so they can be sanded to 3/32" radius smooth. I'm using a Dialarc HF as the Diversion doesn't work well at all on these.