I've just started tack welding the bottom chassis rails. Where three or more rails meet(ie the joint at A1,B2,D1,H)isn't it necessary to fully weld the parts of the joint that will be inaccesible once other rails are tacked.
For example: after tacking A1 and B2, if you tack D1 in place will you still get a satisfactory weld on the outside of A1/B2

Hope this makes sense

Mart

I see what you're getting at.

So long as you're happy with the position of all the bottom rails, all square etc, I don't see why not.

I've not got to that stage yet myself, but I can't see it'd do any harm at all.

Guys?

I just tacked it all up until I finished the chassis and then squeezed the weld in place later....Feels real solid to me. Just rememeber it's lots more of a bitch to cut full welds. I bolted all my bottom rails down with small wooden blocks to keep it flat and square...

I used pipe clamps routed through holes that I drilled in the work table... keeps everything really flat.

However... looking back... I recommend:

- tack welding around the perimeter of the bottom rail layout
- fully weld only the top seam where H will sit a top the junction of A/B/D... let it cool
- flip the whole thing over, clamp it down, and fully weld the opposite seam... let it cool
- grind flat the full welds
- keep tack welding


In short, only fully weld what you must, and always counter-weld to keep things balanced.


cheers,
-Jim M.

Yes jims right , dont fully weld unless it is firmly held in a jig, once i marked out my plyboard sheet i cut 3" lengths of angle iron and screwed them to the lines to stop the frame moving. Also try the magnetic welders clamps, quite good..
good look phil....