Power drawbar failure

[coldte]

After getting fed up with clouting the draw bar with a mallet to release 3mt collet holders etc and at times it takes some doing , i purchased a butterfly wrench as per info obtained via the net , manufactured the frame assy and after purchasing deep impact socket for the draw bar connected it up and nothing , it worked ok the wrench tightened the drawbar but on trying to release it spun it loose but no release . It appears that the hammer action will not release the taper . Question; Are 3m tapers difficult to release compared with R8 or any of the other machine tapers , if so any suggestions as to solving the problem?
thankyou
coldte

 

[LADmachining]

Morse tapers (MT) are self-locking, and require a tap on the drawbar to release the taper, as you have found. If the drawbar is tightened too much, the taper can become very difficult to release.

The angled portion of the R8 system is a lot steeper than the MT, so it releases automatically when the drawbar is loosened.

I have heard of designs for self-ejecting drawbars for MT taper systems. I do not have a link available though. :shrug:...

Anthony

 

[ozzie46]

coldte;

I use a tuning/pickle fork tool. The kind used to separate ball joints from tie rod ends.
If the end mill holder has a gap between the holder and the spindle you can put the tips of the forks in and a few gentle rocks of the fork gets it loose. Don't go hog wild on tightening the draw bar. It doesn't need it. Snug and then about 1/2 to 3/4 turn is enough on my setup.

Ron

 

[Ed T]

I also have a mill with MT collets so I understand your problem. I don't have a cure for it, but R-8 collets (at least those I have played with) have a keyway on the side and the spindle bore (on a Bridgeport) has a pin that engages the keyway so the collet can't spin even when loose in the taper. Probably an evolutionary feature to get around the very problem you're having. No help, but a bit of info.