seam welding Thinnest steel?

[zippy500]

What is the thinnest sheet steel that can be seam mig welded.

I have a floor pan to be fitted, going to try butt weld as to lap in my classis resto, my mig seam welding seems to run away from me!!

I can lay down individual tack welds which look quite good

You can image it will take a long to tack weld a floor pan. I don't want to blow holes in the floor pan.

floor pan is probably 1.0mm thick

 

[pedrobedro]

You can seam weld anything if you can get the amps down low enough. With my Minarcmig 180 I can quite easily weld .8 sheet with .8 wire as long as the fit is close enough.

 

[Sean]

0.6mm steel.....0.6mm wire argoshield light and a modified SIP (25A)

chill bars help as does having the steel immaculate and absolutley no gap, ive butted 0.5mm using the thin metal technique but thats not much fun

 

[steveo3002]

would you not replicate the original spot welds rather than seam weld the whole thing

 

[Sean]

if your letting a patch into 1mm floor pan then cut the patch to cover the rust scribe round the patch then cut the floor to just inside the scribe and gently buff back to the scribe with a flap wheel. once you have a good fit tack and tack some more and again till its about every inch, you should be able to run an inch of weld without it dropping through on 1mm

cotamination from paint, underseal oil and even the dust residues from grinding it away contribute to the weld pool popping and blowing holes

 

[atomant48]

chill bars help as does having the steel immaculate and absolutley no gap, ive butted 0.5mm using the thin metal technique but thats not much fun

Ive found on a recent project (welding a large patch into a bonnet) that having no gap actually caused the join to bow upwards or downwards as it cooled. I found leaving a small gap (using the 20mm box panel clamp thingies) gave a better - flatter - result. But i pretty much used the "thin metal (pulse) technique" all the way around.

Does anyone else find this? I guess on a floor pan the ribs etc will tend to provide a bit of rigidity and resist bowing to some degree?

 

[bert]

I cant remember the last time i tried to run a constant bead on any car panels. I only ever use the thin metal technique and I have my clark 100E set almost at max. If i blow through using this then i probably have not cut out enough of the old metal to find a good solid base.

on patching I generally leave a small gap all the way round to ensure 100% penetration.

 

[pedrobedro]

on patching I generally leave a small gap all the way round to ensure 100% penetration.

Don't leave a gap on thin metal, you need it as close as possible not to burn the edges away and there's no problem getting penetration.