Hello mark
This is a quite easy mistake often made by people used to the more modern taper mounts used in industry that have largely superseded the old MT to the point of obsolescence.
The big difference is that the MT was designed as a "self holding" taper whereby the action of inserting it generates sufficient friction to hold it in position and to drive the cutting tool through friction alone
It is however very reliant on the mating surfaces being clean and precise and cannot cope well with radial loads such as those encountered in milling and this led to the incorporation of a draw bar to prevent the risk of the tooling becoming detached not particularly to increase theholding forces.
As you point out overtightening can lead to problems with later removal, particularly if the tooling has been left mounted for a long time.
I have had a Sieg X2 with MT for over ten years and find less than 1/4 turn on the drawbar spanner is needed to nip up the mount. With the drawbar slackened a turn or so and given a sharp rap with a small brass hammer on the end it will "pop" lose for removal
Gerry W
Leeds UK
Sent: 06 January 2016 03:46
To: GrizHFMinimill@yahoogroups.com
Subject: RE: [GrizHFMinimill] Re: Removing collet chuck
We have a little Sherline mill at work for making small fixturing type items. One of my less-machining-savvy coworkers seriously overtightened the collet drawbar & I had a bit of a struggle extracting the collet after that.
The Sherline uses an MT style taper. In my experience, it's not necessary to tighten it much past hand-tight (at least while drilling or milling aluminum). So be careful to not over-tighten the drawbar. I have to remember this because my home machine is an R8 & has a considerably different "feel" when tightening the drawbar.
Mark
__._,_.___
Posted by: gerry waclawiak <gerrywac@hotmail.co.uk>
__,_._,___