Outer Limits 4x4 Board

Suzuki sierra Floor's in particular...

This will be my first time welding anything thinner than pipe with a 4mm+ wall or 4mm plate.

I've got access to oxy/acet and a 120amp mig. and can weld the thicker stuff pretty well with either. But a little unsure as to which way to attack this so I get the best results. My basic plan was to cut the rust plus a little, take any paint/sound deadener off near the weld, cut a sheet off the floor in a mates wreck, cut to suit doing my best to match the stiffening ribs. and then weld a little at a time starting at the centre of each side and working my way out.

My main question is how snug of a fit should the new piece be? I'm guessing I should leave a 1-2mm gap the whole way round?

How far off am I with all of this? Am I more likely to get better results with MIG or oxy/acet+mild steel filler?

hey there mate make the plate fit nicely in the hole probly bout 1 mm gap or even snug it doesnt really matter and they way i would weld it is to put some tacs around it then have ya welder turned down a bit or else you will probly blow holes in it and just take ya time doin small lines at a time.

I'd be making it fit neat as possible if not just 1mm overlap and when welded the small lap should be taken up by the weld penetration leaving no lap and an easier weld to do.

rowenb wrote:I'd be making it fit neat as possible if not just 1mm overlap and when welded the small lap should be taken up by the weld penetration leaving no lap and an easier weld to do.

X2

no gap's and heep's of tack's . befor you start welding you want tacks at leat every 10-15mm . This will keep the seam's nice and even once you start weling it out .
if you want you can basicaly just keep Tacking/spot welding your way around till you've completed the joint , trick is not to let to much heat build up in the pannel .

get your hands on a block of copper and if possible put it behind the part to be welded. This will stop you from blowing holes in the steel. Turn your amps down as low as possible and run solid wire with gas. Make sure the steel is clean with no rust. Weld a bit then move to the other side of the insert. This way you don't concentrate the heat in one place. The Copper will give you a better finish on the other side as there wont be too much hanging down. Oxy is a pain as it causes tha panels to warp. You have to keep wetting it with a rag top remove the heat. Got any copper heads for a soft hammer lying around? Perfect for the job, just chuck it in water when it gets too hot to handle.

How does one clean up the welded area once done? Just flapper/sand/bog/sand? I'm looking at welding up some holes in exterior panels.

The sanding pads with the rubber back on a grinder work better than flapper for flat surfaces and are cheaper. If you're welding the floor i wouldn't bother grinding the weld if its neat enough. I assume carpets goin over the top?

rowenb wrote:The sanding pads with the rubber back on a grinder work better than flapper for flat surfaces and are cheaper. If you're welding the floor i wouldn't bother grinding the weld if its neat enough. I assume carpets goin over the top?

carpet will be going over for rwc but thats all. underside will be cleaned and painted over with brush on sound deadner which should hide most smaller imperfections.

cheers for all the advice. will try chase up a block of copper.

rowenb wrote:The sanding pads with the rubber back on a grinder work better than flapper for flat surfaces and are cheaper.

X2 But I have seen panels warp from to much heat generated by sanding etc so taking the weld down slowy is the best way to do it, just wiping it with the sander then move on.

If is a small non-structural peice (ie not a seat mount etc), sikaflex might be an alternative for you too.

best technique is to tack it inplace then do a run of small tacks ie.. tack once the red deminishes on that tack, tack again.. theres all of 2 seconds between do an inch long then move to another side dont get it too hot...

you tube mig welding car panels