I want to weld up a modestly heavy steel table to build a 4x8(+) CNC router for sheet goods. I can of course take the attitide that sheets goods are mostly just cut through so as long as the spindle roughly follows the warp of the table its mostly ok... and it really would be. Well for depth anyway. LOL.
I'd like to do a little better than that. I know I'll have to shim and space the rails to get it as good as I want it, but I'd like to start with the best table I am capable of. Maybe not the best some of the rest of you are capable of.
My thought is to clamp up the tube as best as I can to get it square, tack the 4 corners of each join whether its a t-joint or a brace joint, and then only weld in the longitudinal direction along the main runners and legs.
What else can I do? Yeah I know the tube isn't straight. I'll just have to adjust for that. Cross pieces cut to a stop, and legs cut to a stop may help, but I know they still won't make it perfect.
P.S. I'm strictly a hack welder. I've never taken a welding class in my life. Just hacked it out. I'd have to say most of what I know about welding I learned from his group. I have a flux core only Lincoln MIG, and decent Miller Mig (212 NOT Autoset), and an old Lincoln AC Cracker box.
I seem to weld the best with the little flux core mig, but the tube wall is right at the limit for it, and it has a very low duty cycle.
I mostly use the 212 for aluminum with a spool gun, but its dual stinger dual tank so switching to steel is just a matter of grabbing the other stinger. I have some tri mix on the stinger and I do not like how it welds. I've been told I'd be better off saving that for stainless and get a bottle of C25 for regular daily work. I could of course throw a spool of flux core in it, but I really don't want to run that nasty stuff in my nice machine.
On heavier stock I seem to do the best with the AC cracker box, but it also has a limited duty cycle. It doesn't shut down, but the welds start to get nasty looking. A ten minute cool down and its ready to go again.