How To Repurpose Center Drill?

[ericc]

I read somewhere that a broken center drill could be reuse as a spotting drill by grinding off the rest of the nub. This doesn't work. The drill won't drill. I tried grinding a facet at a shallower angle at the cutting edge. This works,but requires quite a bit of drilling force. Is this expected? Or does the web need to be relieved as well. Center drills don't really look like spotting drills in the center, and probably they shouldn't because that wasn't their original purpose. It would be nice to repurpose them since they are pretty common.

 

[tertiaryjim]

I've hand sharpened and reground/re-purposed a number of center drills. Relieving the web has also worked well for me though many will caution that it can't be perfectly ground on center by hand and may
pull off center a bit.
Grinding lip relief on a 118deg bit is easy but grinding 45 or 60deg relief is much more difficult.
One lip can be ground down and the other sharpened for your purpose. I find this is a bit more easy.
Save all the old/broken high speed tools for those special needs.

 

[old toolmaker]

Broken center drills can be re-purposed for boring bar bits, special lathe bits and special form tools. I save any I might have. They come in handy at times and cost nothing.

 

[Jimsehr]

I have hand ground broken centerdrills for years. If the tip is gone you can make them into spotting drills. Just keep trying till you get the hang of it. And try to learn how to split the points.
Jimsehr
.

 

[ericc]

Hi Jim. Thanks to a kind forum member who helped show me, I can do it now. I just ground one and it worked great. Thanks, Jim.