Welding Tips and Tricks

Hello forum This is my first (likely of many) post. I am building a grille shell and grille for a 1940 Ford COE cab. The grille shell is 20 gauge steel. The large elliptical opening in the center of the shell that will contain the grille will be supported by round pipe that has been rolled to form the ellipse perimeter.

I need to weld or braze the 20 gauge shell to this 1/8 inch thick steel pipe. Quite a thickness difference. This shell to pipe lap joint is not structural. It’s more of an appearance issue on the front face of this grille/shell.

How do I connect these two pieces of steel. Tig or mig? Silicon bronze wire/filler?
Thanks for your advice.

hi
what process is up to you. tig, mig, gas, stick, it all works.

its simply a matter of thick to thin. takes a bit of practise. generally you don't weld the join directly, you weld on the thick part and wash over to the thin part.
what can make it difficult is if your also having to weld over a gap. if you can get perfect fit up it will be a whole lot easier.
the other thing to think about is controlling warpage.

Tweake
Thanks much. The sheet metal when clamped in place has no gap. My thought was that silicon bronze with its lower melting point would be easier to braze the thick to thin decreasing the chance of melting the edge of the 20 gauge. Just not sure if mig would be easier than tig. I am less experienced with tig.

Thoughts?

SilBr is an excellent choice for the very reasons you outline. MIG SilBr uses 100% argon, not 75/25, so don’t make that mistake.

If you do MIG it, tack tack tack! Put lots of tacks along the ellipse before you undertake finish welding it. Also, the more you tack, the more the sheet metal will soak up heat, so be patient and skip around. You can also use an air hose to help cool the material regularly.

The hardest part of body work welding is having the patience to let the material rest.

mig will be fine if your using thin hard wire. (0.25" i think it is). its more down to the fact you don't weld directly on the thin. weld on the thick and move over and clip the thin.
i find it easier if you use the O style manipulation and make sure the cross over is on the thick side. it can take a bit to get mig settings dialed in because you need to run hotter than the thin material.

with tig its similar. build up some metal on the thick then wash it over to the thin.

practise first.

welddoc88 wrote: ↑Fri Jul 15, 2022 10:02 pm My thought was that silicon bronze with its lower melting point would be easier to braze the thick to thin decreasing the chance of melting the edge of the 20 gauge.

Although true, the biggest challenge on things like this will be to control the inevitable warping that will happen to the sheet steel. Burning back the sheet is really the least of your challenges

Make sure to work on very small sections at a time and 'jump' from one end to the other constantly and like one of the other posters already mentioned, let it rest and cool/equalise often. Avoid giving in to the temptation of welding/brazing such a piece out in 1 go.

Still.. I hope your sheet-metal working skills are OK as some deformation/warping is inevitable on thin sheet and you'll need to work out any resulting dips and bumps with hammers and dollies and the like.

If you do braze then a little 'lip' on the plate metal that lies over/on the thick hoop is an advantage as the braze can wick between and increase the bonding area and it's strenght.

The advantage of brazing something like this is that it's a little more ductile and will be less prone to cracking on the 'weld' with any required sheet metal work afterwards.

Bye, Arno.