I have been grinding and lapping carbide tools by hand for over 30
years. I have gotten pretty good at it. But with the relatively newer
micrograin carbides it is possible to buy carbide inserts for aluminum
that are extremely sharp and with a polished finish. It is hard for me
to attain the very highly polished surfaces in a reasonable time. So
normally I just buy inserts. But occasionally I need a special tool
shape or radius or whatever and I make my own tool or modify an
insert. I use diamond paste with cast iron lapping wheels and flats.
When using a wheel to lap a positive rake cutter is it better to have
the direction of the wheel going down in relation to the cutter, as if
the cutter was cutting the wheel, or is it better to have the wheel
rotate in the opposite direction? I am lapping with the flat side of
the wheel, not the periphery. Similar to an Accu-Finish
grinder/lapper. The machine I use is a Leonard Grind-R-Lap which is a
slow spinning machine and the precurser to the Accu-Finish machine.
I'm thinking that if the wheel is going past the cutter in a downward
direction that minute particles of diamond that have been freed from
the wheel surface and particles of carbide removed from the cutter
might tend to pile up on the cutter edge and round it slightly. On the
other hand, if the wheel direction is up past the cutter will the
diamond tend to pull particles from the cutting edge leaving it
ragged? With the older, larger carbide particles it was better to have
the wheel going down past the edge. But now I want to achieve the
sharpest possible edge I can with the better carbide available.
Thanks,
Eric