Shop teacher in Gary, Indiana told me to fit up cold and I owe him for it
I was fitting a 48 inch shell course back in 2019 and my old shop teacher walked through the yard and watched me tack it hot. He said stop, let it cool, fit it cold, and check your gaps before you ever strike an arc. I blew him off for about 20 minutes until the thing pulled a quarter inch out of round and we had to cut three tacks loose. Now I fit everything cold in 4 spots minimum and my rework on roundness is basically zero. What's your fit up routine on big diameter shells, do you tack hot or cold?