"Gary Wooding" wrote in message
...
Bill Schwab wrote:
I am very much leaning toward the ER32 solution, but want to read a
little more before buying them. Basically, I do not care (much) about
the height of the chuck, but I do care about the relative height between
the business end of a drill bit and an end mill, and about the vertical
space required to make the common changes.

One question about ER32, and put this to the seller I listed, is how
much room does one need to change a collet? It looks a lot more spindle
friendly than changing an R8 collet. ER32

Since you don't need to remove the chuck, and the collet closer is not
as deep as the collets, the vertical space needed to change a collet is
just a little more than the hight of a collet, which is 40mm.

The friend who pointed me towards the ER system has a Myford mill with
an R8 spindle. Although he has almost the complete set of R8 collets he
decided to switch to ER and never regretted it. Unlike the R8s, each ER
collet covers a 1mm range, so with ER32, for example, the complete set
of 18 collets allow you to grip any diam. from 2-20mm. Neither of us
have yet experienced the problem of endmills working their way out of
the chuck. It could happen, of course, but we haven't had it happen.


It is generally accepted that end mills should not be run from chucks, due
in part to the hardened shanks, which do not hold well by that method, nor
are they supported properly for the serious forces generated in the cut.
It's far different from a twist drill, which has a soft shank and typically
does all its cutting on the end, so there are no side forces. While you
can, and probably do, achieve a level of success, such a setup is prone to
eccentricity, chatter and hogging, which is reduced by the use of a proper
collet setup. These words I say in the hopes of helping a newbie.
I realize you folks know it. :-)

Harold