Bob Engelhardt wrote:

wrote:
Are you aware you can grind any drill bit, including Metric, flat on
the tip and use it for counterboring? ...

Without a pilot? It doesn't wander? If not, why not?


"Paul wrote:

Are you aware you can grind any drill bit, including Metric, flat on
the tip and use it for counterboring? First, start the hole with a
normal drill bit of the size you need, and then finish it with the
flat bottom drill."

The drilled hole using a conventional hole is the pilot. The flat ground one guides on
the previous drilled hole and takes out the drill cusp.

Wes