Hi there.
I am aboute so start making a chassis for a locost based on a BMW e30, my question is about if I schould tig or mig weld the chassis. If you recommend MIG welding, schould I make 2mm clearrence between the pipes for better result.
Pls. Advise.
Best regards
Cr325

Mig weld and if you are using thin wall tubing no gap is needed.

quote:

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Originally posted by Peteff
Mig weld and if you are using thin wall tubing no gap is needed.

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Do you fiend off.the welding afterwards. Since.MIG.leaves some material after.welding, when welding without a gab

I meant grind off the welding. :-)

I only ground off the welds where I wanted a flat surface, as with fitting the side alloy panels and floor, other than that just left as was. HTH Ray

[Edited on 26-11-11 by Chippy]

I use a 60 grit fibre disc on the angle grinder to take the tops off the weld where any panels are going to sit others are left alone and just painted with the rest of the chassis. The weld penetrates into the metal it doesn't work like glue so if you just level the top off there will be metal still holding it together

I wouldn't leave any gaps, you'll get plenty penetration when MIG welding 2mm box section once you're practiced at it & it'll be much easier to assemble with the parts cut dead on the right length so they meet right up rather than trying to get the gap right all the time.

I used 2mm tube, no gaps but I 'v' preped all the joints before welding

[Edited on 27/11/11 by will_08]

in my opinion there is no need to prep that size of box section. butt up tight, then MIG weld, prob around equivelent of 120amps, dependent on machine and wire feed speed.

i may TIG mine, but to be honest think it will take so much longer for no gain. a properly setup MIG using argon/co2 mix will produce very tidy welds in the right hands.

v prepping and leaving a root gap is for much heavier metals than 25x25 box section.

as said above it will also aid fabrication by butting the chassis tight up, cutting each section in turn, etc.

im looking forward to getting started on my build, but the fabrication bit will be the easy bit, as im welding most days at work anyway.