Spot weld cutter???

Larry, I have two kinds and have used them. Both work. Depends on how much access you have, and whether you intend to reattach a part again later. Type 1 is simply an odd-looking 'drill-bit' that really needs a clamp system (think portable drill-press with a magnetic base) to keep the reverse-ground 'drill' from wandering. It often goes thru both sheets of thin steel if you push too hard, same as a std drill bit. They are usually high-speed steel & need lots of cutting oil or they dull rapidly. I always have trouble with these things.

Type 2 is a tiny hole-saw (some are carbide; long-lasting but brittle)) that removes a little disc from the top sheet without penetrating the second (much). Needs the same kind of lube & clamp/guide system or it will wander, and it leaves a large-ish hole. Some of both types use pilots for hand drilling but pilots won't correct for drilling angled or off-center with any hand-held cutter. The little saw will absolutely remove all of a spot weld; reattaching the same part later means rosebud-welding each big hole you cut, to fill in the removed disc (only if you intend to reuse the part). The result will not look stock without a LOT of work on each hole.

I've also used a thin chisel & hammer between 2 sheets to tear spot welds apart without any drilling, but this also often wrecks any re-use of the removed part. Simple, cheap, needs very little access and you can even use a small air-chisel. You'll find that some spot welds are very firm while others are almost not there. Those are easiest done with a chisel & hammer. Save the spot-weld cutters for the really difficult ones.

Hi Larry,
To add to Boss' remarks.... I use "type 2". I have tried a few and find the harbor freight pieces work as well as any other I have tried. Additionally, I grab them for inventory whenever there is a good sale, so they are even cheaper. My bottom line is if lubricated (I just use WD40)and some good force is applied (so they are cutting, not rubbing) I get as good of tooth life out of them as the others. I have found that when you screw up, they all brake..regardless of entry price. They have reversible blades / double sided, and I would guess I get 30 to 40 or so welds cut before it needs flipping/replacing.

I can usually tell when I'm through only the outer layer, but occasionally I will accidentally go through both. I usually see a little puff of dust/rust, or hear a small pop when I get through the outer layer.

I then grind down the old spot weld "disc" for installation of the new piece. In areas that I can't do real spot welding, I will actually use these cutters to make holes in the new panel, and mig weld fill the hole. Once you get into a rhythm, they look respectably close to spot welds.

El cheapo spot weld cutters

When in a bind, I will use the air chisel, however have found it fairly destructive, so don't often resort to this approach.

In the 4042 thread you can see some of this in action. Hope this helps.....

Unibits work very well and much harder then the std drill bit ...

If the area is accessible such as a floor pan, a grinder & "PATIENCE" achieve the best results. Grind the spot welds & remove the part/s.