The reason used to be that carbide inserts are not as sharp on their cutting
edge as HSS, so they generate more load on the part being machined. Not sure
if thats still true. Some of the stuff the model engineers make is tiny, and
so are their machines, so carbide was not an option. Its the same reason for
not having a flat top on the tool, back rake gives it more of a slicing
action, lowering the load on the tool and part.

regards,

John


"michael" wrote in message
...
Why not just get insert holders and use inserts with geometry that you
can't get by grinding?

michael