Posted by Joe Lorenzino on Tuesday, May 18, 2004 at 0:55AM :
In Reply to: Re: Breaking Spot Welds?? posted by Paul B on Monday, May 17, 2004 at 11:34PM :
At work, we use a combination of the methods already mentioned, with a few added twists. If putting new panels on with a mig welder, we drill a hole at least as large as the spot weld, through both pieces, from the "throw away" side. Then, instead of a chissel, I use a heavy old putty knife with brass handles on a blade that goes all the way to the back. It cuts very well when used with a hammer, and does not distort the "keep it" side as badly. I have also made up longer "chissels" from old tapered leaf springs. We flatten them out, notch out a piece of shafting for welding on (with soft stainless rod)as a handle/hammer surface, and sharpen the thin end as a cutting edge.We have made these up to 20" in length for reaching spot welds in farm equipment panels, and the guys haven't broken one yet. When we weld things back together with the mig, we use a piece of 5/8"aluminum plate as a "chill plate" behind the new piece, and plug weld it on quite hot from the side with the hole. The chill plate makes sure that you have little or no grinding to do on the face of the new material. We ALWAYS use a welding visegrip (the horse shoe shaped one) to hold the panels and the chill plate together while welding. Skip around while welding, instead of going from one end to the other. If the seam curves due to the welding heat, allow it to cool, then "strech" the welds by hammering them with a back up dolly. J.V.L.