Any reason I can't use a flattened piece of copper tube to back a weld? :confused:

No reason what so ever. The MIG weld will not stick to it. It works great for filling holes.

Thanks Brian - made sense, but I wanted to be sure graemlins/clonk.gif

Be sure to wear golves. That copper will heat up in a hurry!

Randy sounds like you know from experience smile.gif

Originally posted by sevt_chevelle:
Randy sounds like you know from experience smile.gif Let's just say that there is no such thing as quick little tack weld! redface.gif

I have used steel pop rivets when doing small holes. Install the rivet as usual, weld in place, then finish off with a flap wheel. Go to the back of the panel and finish it off as well with a quick hit of the flap wheel. The density of the rivet alows it to act as a heat sink. You can get a good penetration weld that will resemble a factory spot weld before finishing it.

I get scrap copper from work along with brass and aluminum which also work fine as backers.Some kinds of stainless will work also.