I probably missed it, thought this was the thread about the pin being
long in import mills. The drawbar may be too long, so the threads are
bottoming out before you pull the collet closed. Add a few washers
under the head if this is the case and see if it helps. You can make a
shoulder washer for the top of the spindle for a nicer job.
On 04/02/2013 03:02 AM, John Herrmann wrote:
> Robert -
> I know this is now a relatively old thread, and maybe you've found the solution already. Nevertheless, here's my two cents' worth:
> Given that
> (1) your collets don't close when reefing on the drawbar
> (2) you only see a small amount of taper contact when using dykem
> (3) the collets seem to work OK when you wrap the taper
> I'd say that somebody's (sorry, forgot who first said it) suggestion about the collets being a bit too long has a lot of merit.
> You can check this pretty easily. Pick one of your new collets. Make sure there's no grit or burrs in the slots, and that you can close the slots by hand before putting it into the spindle. Now put the collet in the spindle *without* a mill inside. Tighten the drawbar (fingers should be enough). The gaps in the collet should close up pretty much all the way. If the drawbar seems to "hit bottom" (ie, become hard to rotate) before the collet closes, that's evidence the top of the collet is being stopped from moving upward as far as it should.
> If that's the case, you can try grinding a bit from the top of one collet and repeat the test. If it closes further or all the way, you've verified the problem and the fix. Proceed to grind all of them, and you're good to go!
> - John Herrmann