"Gunner" wrote in message
...
snip--

While I use collets (30 taper) almost exclusively..I have had endmills
move in the collets, screwing up the work when taking very heavy cuts.

Yep, that's a common occurrence if you're crowding the cut. It is fairly
easy to get around, just make sure that you assemble the collet and end mill
with absolutely NO lubrication on the shank of the end mill and the collet
interior. It's not beyond reason to use acetone or lacquer thinner to
make sure they're absolutely clean of lubrication, then tighten the collet
well. In truth, both holding systems present their own problems, but
neither of them should be considered a bad system.


They tend to screw Into the work, pulling the end mill deeper into
the workpiece. I still use them, but I make sure they are TIGHT and if
Im going to make agressive cuts..I stick in an endmill holder Every
time. Normal stuff..no biggie. The Collets your VN use are pretty
darned good holders..so I wouldnt worry about having problems.

There are left hand spiral end mills on the market the can work in the
opposite direction if pulling is a serious problem and one has no end mill
holders. They push the end mill into the collet instead of out, usually
stopping the movement fairly quickly because of the lighter load. Needless
to say, if you're working near the table, or you have depth constraints, one
of them can be worth it's weight in gold. I recall ruining a master
tracer template for the Boeing 747 years ago, a job I had subcontracted from
a larger shop, which had in turn sub-contracted from a source outside of
Boeing. End mill pulled out unnoticed, cutting way too deep. Sigh!

Harold