"Bob Engelhardt" wrote in message
...
Jim Wilkins wrote:
Are the cutting edges properly angled to turn down the diameter and face
the resulting shoulder when the toolpost is set square? I can't tell from
your photo. I have to grind the point angle to less than 80 degrees to be
sure my Multifix with 9 degree setting steps will allow the bit to cut
both ways.

The one that I made requires the toolpost to be angled, maybe 20 degrees.
The commercial one somewhat less. The bit is ground on one surface only,
but the point is less than 90 degrees, allowing shoulder-ing.

Bob

I set the compound to 29 degrees and the tool post square for parting, and
leave them there unless absolutely necessary. I wouldn't disturb them to
avoid an easy non-precision grinding job.

The diamond holder makes more sense with form tools that are difficult to
sharpen by grinding the outline. There are threading bit holders made that
way, except that the bit has ribs that mate with the clamping surface to
keep it from sliding down under the cutting pressure.

jsw