Welding Thick To Thin Metal.

[Guest rich205]

Do any of you guys have any tips for welding steel of two different thicknesses together.

 

The reason I ask is that the mounting feet for the cage (OMP bolt in) that I'm going to fit are substantially thicker than the floor and sills of the car. IIRC the mounting feet are 4mm thick and I guess the floor is about 1mm.

 

I have some experience mig welding, and therefore know how easy it is to blow holes in thin bodywork. So my concern is that by using a suitable power setting for the thin bodywork, will I get adequate penetration in the thicker cage mount?

 

I was also thinking about reinforcing the floor and sill where the cage mounts with another sheet of thin steel, then welding the mounting foot onto this double layer.

 

Your opinions are welcome.

 

Cheers, Rich

[Pugnut 9 1 Cars]

chamfer the edges of the thick plate . and most important of all - practice on a test piece first.

[Pugnut 9 1 Cars]

welding the mounting foot onto a thin plate , then onto the floor ?

 

seems pretty pointless in my opinion especially on the main hoop feet , but if you can get ones on the underside of the body and bolt right through sandwiching the body inbetween two plates it should add strength, but if its an sd cage you'll only really manage this sucessfully on the two front feetand possibly one of the bolts on the rear feet

[Guest rich205]

Thanks for the advice, I like the idea of chamfering the edges. Thinking about it, welding another thin plate to the floor first probably isn't going to achieve much as the cage mount foot will then only be attached to that, and so will be less solidly fixed to the floor.

 

Cheers, Rich

[16v205 9]

Im not sure if its right or wrong but this is what i do.

 

I chamfer the edge of the thicker metal, then set the welder for the thicker of the two materials and strike against the thicker plate. Once the pools up and going i dip into the thinner metal and back into the thick plate. I seem to get good penetration this way without blowing many holes in the thinner stuff. Id prefer to get good penetration of the thicker plate and risk blowing than get good penetration of the thinner stuff and a surface weld on the thick plate.

 

Rich

[M_R_205 5 1 Cars]

16v205 is spot on, thats exactley how i do it, it also helps to do it in sections and leting it cool down slightly,

[Guest rich205]

Thanks chaps, think I'll practice on some scrap metal first.

 

One other question though; the cage I have is the lightweight OMP chromoly one. Now I'm planning to fit door bars when the cage is in the car, but I'm unsure if any special techniques, or a different filler wire is required for welding chromoly steel. Or if you can weld chromoly to regular mild steel?

 

Can anyone shed any light on this?

 

Cheers, Rich