What size of spot weld drill bit

[crj7driver]

I am on to the body work of my frame off and need to pick up a spot weld drill bit. When I went to eastwood, it never occured to me that they came in different sizes. So what size is the best for the spot welds on a TR6? 8mm, 10mm, 3/8, 1/2, other?

Thanks

 

[TR6oldtimer]

I am not a millimeter guy, but 3/8's bit works fine for me. Plenty wide enough to span dimpled welds. Get a couple, they are easily dulled.

Remember, you are only going through the top piece of sheet metal with the spot weld drill bit. Hopefully the piece you are replacing.

I found that when removing an old panel, a cutoff wheel and grinder took care of most of the welds, making the spot weld drill bit a little used, but when needed a handy tool.

 

[martx-5]

When I was removing welded panels on my TR3 resto, I found that just using a regular 3/16" drill bit in the middle of the spot weld worked better then any specialty spot welding drills. I played around with different style drills, and finally settled on 3/16" cobalts that have a 135 deg. split point. Try differnet sizes, to see what works best for you. Then get several of that size in cobalt. Cobalts always have the 135 deg. split point. The split point centers much better then the standard chisel point, and cobalts last much longer then high speed. Sometimes the 3/16" size (or whatever size you found to work) isn't quite large enough in diameter to free the weld, but once all of the welds in a section are drilled, the stubborn ones can usually be finished off with a thin chisel between the panels. If you're careful with the drilling, the grinding afterward is minimal.