Awl--
Iny trad'l methods? idears?
Here's my 2c:
A triangular insert is circumscribed by a circle whose diameter is 1.15 x the length of an edge of the insert. Or, if measuring perpendicularly from an edge to a vertex, mult. by 1.33. Barring faulty algebra. :)
Along those same, uh, lines, a triangular endmiill should obey the same relationship, *even tho* the corners are rounded--I think.
With endmills, it's def'ly easier to measure flat-to-vertex, and for a 10 deg conical 3-flute em, a .110 measurement indicates about a .147 diam tip. It's a "Conical" conical 10 deg (# J203, USA made), if anyone has any data to perhaps verify this.
If anyone wants the derivation, ax or email.