[cdunson]

My uncle showed me a trick once when we were welding on my car. In areas where you have a small hole to fill or a slight gap we used a copper block (I think it was anyway) behind the panel so that the weld wouldn't go through nor would it stick to the block.

Is that the right metal I'm thinking of?
​

 

[BelAirBob]

Yes, Copper is the correct metal to use. It dissipates the heat cutting down on warpage,and the MIG welds will not stick to it.

 

[Daydreamer]

yes it is, It's called a copper backer. I use one when filling holes. Make life so much easier. The copper does get hot fast so use a glove or vise grips to hold.

 

[Daral]

If your hole is in a flat spot where you can't get vise grips on it and you can't reach it with a glove, like the middle of your trunk, I found that a couple strong magnets work well to hold the copper in place.

 

[Daral]

OH, and make sure the magnets are not close to the spot you are welding. They could distort the weld.

 

[dnult]

I've used those right angle magnets before and it does some crazy weird stuff to your bead.

 

[Matt M.]

I like to use a piece of 3/4–inch copper water pipe (about 10 to 12-inches long). I smash the end flat and then bend it over.

 

[DHONDAGOD]

Brass hammer heads, drift's, aluminum blocks or round stock work well too...



Chris