A rule of thumb that has served me well is: Ok to use collets for holding
endmills under 3/4 inch. Above that, endmill holders are required.

Bob Swinney
"Pete Bergstrom" wrote in message
...

I'm pretty much a newbie to milling (last fall I took a manual machine
tools
class at the local vo-tech and we did turning projects on 13x40 lathes,
milling on Bridgeports, and surface grinding on 6x12 and 6x18 machines).

I found a nice small mill (Schaffner vertical/horizontal, 2hp motor, a
7x30
table on a knee, but no quill) in February and brought it home. It's now
awaiting installation of a VFD to make it go. The mill takes NMTB 30
toolholders, and I've got a few endmill holders in very good visual
condition (I'll check each one with an indicator one of these days). My
plan
is to be able to futz around the shop, and build up my machining skills
with
small projects including robots and tools.

My first question is when would I choose to use a collet chuck, say an ER
or
DA, over an endmill holder. Clearly the collets have the potential to give
lower run-out, but I'm a little worried about the tool pulling out (OK, it
didn't pull out of the R8 collet in the Bridgeport, but that seems like it
had a much larger contact area - maybe I'm wrong).

There doesn't seem to be much of a cost advantage to going with collets vs
EMHs and I'm at the decision point of which type to use as a primary
toolset. Any suggestions?

Thanks,
Pete Bergstrom
St. Paul, MN