View Full Version : TR2/3/3A Drilling spot welds

07-28-2013, 11:16 AM
I'm gearing up to start drilling the tub apart. Just wanted to get an idea of what you guys have done that works, or doesn't work, for drilling out spot welds.


07-28-2013, 11:22 AM
I bought a special drill bit for spot welds... it looks like an end mill. I replaced the rusted floor in my TR6 using this drill bit.

07-28-2013, 12:34 PM
I tried one of those spot weld drill bits - it worked but I convinced myself its not worth the hassle unless you absolutely don't want to drill through all the layers. Seemed likes it was easier to just find a bit that covered the spot weld and drill away and then worry about plug welding everything closed later. And use a spare putty knife as a chisel to separate anything stubborn without distorting things.

Of course, I found I was good at tearing things down that way but I've never tried to put it back together like you have John!

07-28-2013, 02:36 PM
I have one of the spot-weld cutters. I leaves a hole about 1/4in o 5/16in dia.

Most of the spots will breal with a 1/8in or 3/16in ordinary drill.

So you choose if you want a big hole in one panel or smaller holes in two panels. Actually the welds break without going right through both panels sometimes.

How is the chassis doing?


07-29-2013, 07:42 AM
I tried the "spot weld" drills, but wound up using regular drill bits, as there was less "clean up" grinding afterwards. However, i did find that 135 deg split point cobalt stubs worked the best. With he split point, the drill doesn't want to wander around (self-centering). Not ususally a problem drilling out spot welds, but more importantly, they cut with less pressure then chisel point drills. Also, the stub length allows better control. Cobalt because that's usually how split point stubs come. I used a couple of sizes depending on the size of the spot weld. 3/16" most often, followed by an occasional 1/4" .

I also used a stiff putty knife as a chisel every now and then to spring the welds loose.

07-29-2013, 08:01 AM
I use a spot weld cutter. (Link below to picture). Putty knives are OK to separate panels. "Painters tools" are similar but made of thicker steel so you can hammer and pry a bit more.


07-29-2013, 10:25 AM
I tried the spot weld cutters but found drill bits more useful. I think I got a pack from H.F. and went thru a few on the battery box welds. The rockers just took a cold chisel. Inside my trunk, I remember one of my plug welds ended up in the wrong place, and I was happy I had some weld cutters. I was able to cut it out and reposition without too much fuss. So I'd say have a little of everything and use what suits the situation best.

07-29-2013, 10:59 AM
I went the drill bit route as well. I have some spot weld cutters but they seem to be less effective than the drill bits. I found that an air hammer with a thin/sharp chisel bit can help out quite a bit as well. Cheers,Tush

07-29-2013, 11:17 AM
I used spot weld cutters and drill bits. I found the bits would last about as long and cost a lot less. You don't have to drill all the way through the lower panel. Use your die grinder and a Roloc 40 grit pad and expose the welds and drill right on the weld spot. Also, I used a panel knife a lot to separate welds, after I drilled them. I found this tool invaluable for not deforming panels and splitting stubborn welds. Called a Steck Seam Buster. Eastwood has a panel separating knife too, that looks like it is lighter duty.



07-30-2013, 08:48 AM
Thank you all for the responses. I see several tools I did not know existed! I'll have to put them on order and try them out! I'll let you know how it goes...