I've started a new project making intake and discharge plenums for my supercharger and IC tubes all out of aluminum.

I am a hobbiest welding learning this stuff on the fly as I do project on my car. Generally speaking a quality weld produced by me sticks the two pieces of metal together and doesn't leak.....beauty has nothing to do with it.

But yesterday the stars were aligned or something and this happened.

Nice Weld.jpg

Unfortunately it's on the bottom where noone can ever see it.

I'm welding all the joints on both sides, the outside is going pretty well the inside.......stuck together and doesn't leak. I spend alot of time grinding tungsten on those inside welds.

Is there a trick to welding an inside box corner where three sheets come together?