Collets are more convenient, and clamp with less potential 'runout', but
do not hold the cutter as securely as an end mill holder. Sooner or
later you will likely have a collet slip under the cutting force of the
mill. This can (and likely will) cause damage to workpiece and or
cutter, and could cause damage to the operator or machine.

Unless you confine yourself to making very light cuts, end mill holders
are more dependable in the long run. That said, many just use collets
with only rare problems. I HAVE had collets slip, but I still use them
on occasion (odd cutter shank sizes, etc.), though I prefer end mill holders.

Dan Mitchell
==========

Bradford Chaucer wrote:

I just acquired am benchtop vertical mill that takes R8 colletts. It comes
with a drill chuck which I know is not advised for milling. I have seen
sets of both R8 colletts and R8 endmill holders. The difference as I see it
is that the endmill holder protrudes from the end of the sleeve more than
the collett does and it has a set screw for clamping on the flat on an end
mill.
My question is whether a collett is sufficient for holding endmills or am I
advised to opt for the end mill holders??

BTW the mill is the mini-bench top unit sold by Harbor Freight. I made the
"Mistake" of dropping in on the store in South Carolina :-)
Anyone have any comments or suggestions for improving tweaking this unit
(aside from you shouldn't have bought it!!)