On Fri, 29 Aug 2003 12:50:59 +0000 (UTC), DejaVU wrote:
what is DOESN'T do well at all is sneak up on a dimension which is
what the home machinist does a lot of becasue we do ONE part so it is
not set up for production runs to tolerance. sharp HSS can take off
curls of steel that just about float in the air and can be the
difference between a fit and a scrap part. can carbide do that? no
it cannot, because its edge is not *sharp*. Also, HSS is much easier
to grind to shape or sharpen with nothing more than an ordinary bench
grinder with the wheels it came rom China with on it.

Actually, carbide *can* do that. You want *uncoated* carbide. The
coated stuff has a rounded edge, but uncoated carbide can be
scary sharp (and you can make it even more so with a diamond
hone). It'll stay that way a lot longer than HSS too. When it
does dull, just rotate the insert to bring a fresh edge to the work.
You don't have to reset the tool, your geometry is still perfect.

HSS has a place in the shop. It is still the most economical thing
for form cutters, and it stands up well to interrupted cuts. But carbide
insert tooling is the way to go for most shop tasks. Just remember
that for small lathes you want positive rake tooling and *uncoated*
carbide inserts.

The coated negative rake carbide is for the big boys with high
horsepower rigid machinery. It'll handle feeds and speeds you
wouldn't dream of attempting on small machinery, but it won't do fine
shaving cuts. Positive rake uncoated carbide will.

Gary