Welding box section square and flat

[pondy]

I've a frame to make out of 40x40x3 box section for a gate, it's 1 metre wide by 2,metre tall. How do you go about welding somthing like this, keeping is square and flat when you don't have a large enough bench to clamp it all down. Issues I've had previously is once it's tacked up its fine but once welded it twists and the metal is all over the place. Is is mainly down to what bit is welded first, ie outside corner, the sides then inside corner to try and stop everything pulling? Even though I've been on this forum years I'm still very much a beginner a bloke who likes to **** about in his garage about twice a year when the kids let me

 

[Arc Tourist]

Consider tacking the framework together, weld some temporary angle clips on the four corners, lay the framework on the floor, shim it level, check its square, and screw the clips down to the floor to hold everything while welding and cooling. That's what I would do for an occasional "one of" situation. In a workshop, I look at everything being a tool, even the floor.

 

[Mark 2]

If the bench is big enough the I would join two sides then build the other two sides on top of it. You'll only have the one axis to worry about on the floor

 

[Feet 'n Inches]

The floor is no good for me, my back and knees are shot.

I have a makeshift 'bench' mounted on two trestles, a piece of 4ft x 4ft ply screwed to a frame; it's pretty good for level. If I need to work to a greater width then a couple of pieces of 2" x 2" timber can be laid on top.

I tend to position stuff roughly square using a plate square, then tack up and check corner to corner for squareness. Once I'm satisfied, I tack a couple of pieces of scrap angle or small box diagonally, a bit like a knee brace, to catch the sides. The scrap bits are only welded on one side so they can be easily broken by pulling toward the tack. Once welded and cooled, a final check for square and any twist. I've rarely had any problems with this approach but perhaps I've been lucky.

 

[hunter27]

I thought this was a good explanation

 

[pondy]

I've made the frame today. Floor turned out to be a no go as it's not level. I clamped to my small bench. And tacked of section in at a time. Its not perfect but it's very close, no twist and fairly square, you could probably get a bit of paper under the square on a couple joints. A win for me given my lack of space, decent bench and experience!

Followed the video about about weld placement which is the same as welding tips and tricks and is not moved from tacking to welding