Bill Schwab wrote:


to clarify, are you saying the ER32 is a poor choice because it
does not adequately grip endmills, or are you simply telling me not to
put endmills in my shiny new Jacobs chuck (which I would not do)?


The ER system does not have an endmill locking system such as such as is
found in the Clarkson and Autolock systems, so, in theory it is
susceptible to allowing the cutters to work themselves out when making
heavy cuts. In practise, things seem different - at least for the
members of my model engineering club. One member, a retired toolmaker
of immense experience, uses MT collets in his Centec 2B. Another member,
the one who pointed my towards the ER system, eschewed the Clarkson
system in favour of R8, and then switched to ER. Neither have
experienced a cutter working out - nor have I. This could be because,
being hobbyists, we don't take the heavy cuts that are common in
industry. Of course, your mileage may vary.

As far as overhang is concerned, my ER32 chuck is slightly shorter than
the Clarkson, so from that point of view at least, it is slightly better.
The friend who uses MT collets is better off though; his collets don't
protrude from the spindle so there is no overhang at all. He does,
though, need to release the drawbar (and tap it out) every time he
changes a collet. And being that much longer than ER collets he needs
more space below the spindle.

--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)