wrote in message
...
On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread
lead-in?

...I like to finish screws with a rounded end. The
radius used on the end of the screw is much larger than the radius
of
the screw, so the end of the screw isn't quite flat. This type of
finishing of screws is common on screws used in high quality
inspection equipment.
ERic

The rounded form tool can be a quarter-round concave end mill, or
custom ground on a lathe bit with a conical stone in a die grinder.
The conical stone leaves a smooth and circular (or elliptical) edge
that is relieved all around for cutting clearance. You can measure and
mark the desired finish diameter on the stone.
jsw