Power Drawbar Getting Stuck

I have been using a pneumatic power drawbar for about 6 months. I purchased it from Priest Tools. It uses a ram to press against a stack of Belville washers that pull up on the drawbar. The drawbar is connected to an Tormach/Lyndex R8 collet that I use for TTS tooling. For the most part it works great.

I have had a problem a few times when I don’t use the machine for a few weeks and find that the R8 collet sticks and won’t release. To make sure there are no tiny burrs, I very lightly wet sanded the collet and spindle with 2000 paper. I then re-apply anti-seize to the collet and all was good. It worked better than ever!

It worked great for a few months, then I did not use the machine for 3+ weeks and once again it was stuck when tried to use it.

I examined the inside of the spindle and could see some marks where the slots in the R8 collet have been rubbing against the inside of the spindle (Please see below). There are marks like this for each of the three slots on the R8 collet. Does this look normal? If not, any idea as to how to stop these from happening? Better yet… any idea as to how to stop this thing from getting stuck?

Sorry I missed your post. Perhaps unrelated, but the problem I had with the drawbar was with the set screw inside the spindle the keeps the collet from spinning. Too tight and the collet won’t release, but if it is too loose, then during a heavy cut it will skip over the slot and deform the collet. My damage collet then left a similar mark on the inside of my spindle.

Since it has been several months, let me know if you discovered a different cause of this issue besides the one I mentioned.