weld shrinkage

Center tack and weld the flats first . Then center tack and weld the inside corners a quarter at a time alternating sides . Good clamping can't hurt . And small beads are going to pull less than big ones . Don't you have a wire welder ?

I would weld the outside edges, rather than the inside corners. Maybe a tiny bit weaker.

That's what I thought. I bought the acetylene tank after the blacksmithing class last year and haven't gas welded anything this large yet, and want to try on something non-critical like this tee that I can saw apart and do over.

Based on experience with similar square tubing joints on the sawmill frame I plan to weld the outside flat joints but not the inside corners, then grind flush and add triangular gusset plates.

The sawmill's open-ended ladder frame stayed straight until I welded the rungs' inside corners, then cooling shrinkage pulled the outer ends together and I had to jack them back parallel.

The ladder frame ends have to be open to install the bandsaw blade.

On 7/8/2019 11:03 AM, Jim Wilkins wrote: ...

I once stick welded a 3/8" plate to another 3/8" plate, in a tee. There was only inside corners & I was astonished how much the plate was bent by the cooling weld. When you consider how little leverage the weld has, the force has to be extreme.