[marsheng]

I've had my Doall CNC mill for 8 or so years. It is probably a mid 1980 machine. It works 3-8 hours most days. It has a pneumatic tool changer which works very well. Literally used 10k time over the past 8 years. Recently however, the tools are not dropping out when I use the air control. The pressure is there to force the tool down, but, now 9 out of 10 times I have to use a screwdriver to break the taper lock.


I was wondering if after so many uses, that the taper lock has bedded itself in with the tools so perfectly that it doesn't want to release any more.

PS if I keep the pneumatic button pressed, the spindle actually moves down with the tool still in place.

Any suggestions?

[RICHARD ZASTROW]

Have you cleaned the inside of the spindle taper? And the outside of the tool shank tapers? They can collect a coating of oil and coolant film that makes them stick in the spindle. Ditto the I.D. taper.

Dick Z

[underthetire]

And check to make sure the spindle is not heating up. That can sweat tools in.

[JimBoyce]

The spindle moves down? This could be the cause, that should be checked out since it could be stealing the movement needed to disengage the holder.

[handlewanker]

"the spindle moves down"!!!!....this sounds like a spindle rebuild, unless you mean the quill moves down....the spindle is inside the quill....usually......

I had to apply some wet and dry paper on a stick to clean the inside of my Int 40 taper on my Ajax mill ( manual)....it had a patina of dark brown dried oil residue that made the tool run out almost .04mm......I got a shock when I tested some new ER collets and found the all ran out ( before cleaning)....LOL.....now they run dead true.
Ian.