Jeff,
That's why we refer to ball-end mills by 'tip radius', and the flats on v-engravers as 'tip diameter'. 'least... that's the way I was always taught to differentiate them.
Don,
"A flat seems to be counter intuitive for engraving to me and less useful.
Where to they come from the engravers with a flat?"
Most two-flute types have a 'drill bit-like' face, not unlike that of twist drill or an end mill. It's not truly a flat -- It's really two 'wings' that cause a circular flat-milled surface when touched to the work. The face-ends of the two flutes are beveled and sharpened. Don't ask ME how they work a flute that small! I'm still trying to figure out 10-mil diameter carbide twist drills! <G>
All my good carbide v-mills are like that. I have not a single one with a radiused tip. You can get the carbide Vees all the way down to tip diameters of 2-mils. The smaller they are, the easier they are to break, of course. I won't even handle mine anywhere but on a rubber work pad. Even a 2" drop to a metal surface might chip that little point.
Oh... for reasons cited earlier... don't buy the cheap off-shore cutters. I get the best I can muster when I'm working with diameters that small. A couple of mils runout on a cutter 2 mils in diameter is 100%!
LLoyd
