I thought I would start working on removing the rear quarter on the passenger side of the Chevelle. A previous owner cut it across the top and did not weld things back together. As well, the bottom (behind the rear tire) was rotted out. Finally, just behind the door the panel had a decent size crack.
The question I had was how to remove the spot welds. I've tried the fancy spot weld cutting bits and was underwhelmed with them. They broke often and I have quite a few spot welds to cut through.
Looking at:
I have the sander / grinder he is using (yes, I realize that the presenter leaves much to be desired). I tried that and it worked, but it seemed like it was taking a long time.
I then tried use the plasma cutter to remove the spot welds, as shown at:
So far, the plasma cutter has done an excellent job. It does take a steady hand, though. I did put a couple of pin holes in the base panel when my attention was not fully on the work, but those will easily fill with the TIG. If I simply go along the edge of the two panels pointing outward, then bringing it into the panel, I can do it without any base metal damage (even less than what the video shows).
I knock them down with a small 3M weld grinding disc in a die grinder followed by a hit with a very sharp cold chisel bit in my air chisel. I like the plasma cutter idea but i don't have one. I hate drilling out spot welds. This method is very quick.
Same advice on a good quality cutter, but the big thing for me is getting myself in the right frame of mind. It is tedious as hell, no way around that. No matter how careful I try to be, I always mangle the flange somewhere and have to do a bunch of work on it. I've even had to just give up before and chop the old flange off completely, remake that, then bring in the new panel....
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You remind me of the timing on a turbo engine...
try a air belt sander you would be surprised how easy it grinds weld and pretty precise at that I have a cheap astro one and some 60 grit belts and just use the tip of it
Use a spring loaded Center punch and spot weld cutter. The trick is to center punch the spot weld so the cutter has a guide. Then start off slow with the spot weld cutter. Once it starts cutting you can apply more pressure and go faster.
I use the cheap Harbor freight spot weld cutters. I've used the same one for tons of cuts before I pressed to hard being in a rush and broke one. I just flipped it over since it's two cutters in one and went back to work. $5 for the cutter . Perfect for someone who's not going to use it for me then one project.
I use the Blairs also. Center punch and also a quick hit with a 1/8" or so bit (not all the way through) so it doesn't wander. I drilled about 50 this afternoon taking my cowl off.
I like the spot weld cutting bits that have the spring loaded centering pin. Use a center punch first for the pin, and the rest is easy. You hardly ever end up going through the backing sheet metal, and you don't have any holes to weld up either. I used to grind everything and then hit it with a chisel, and still do on messy ones, but the tool is WAY more efficient!