I guess I got no idea what the need for a collet or adapter is. But I do have a suggestion for the draw bar. I personally don't think the little hardened balls are going to work for pulling in the pull stud. I started out with that very same idea, but now have work toward gripper fingers instead. My problem with the balls was one of accuracy. In order to keep from pushing the pull stud out of alignment with the spindle center line, they would need to contact the ramp on the pull stud in exactly the same place. I felt a lot had to be right for that to happen with little room for error. With fingers, or pedals as I hear them called, I think they are more forgiving as they provide a means to turn the holding feature all in one operation yielding a uniform ramp to match the ramp on the pull studs. In addition, they add way more contact area than any number of balls ever could.

It doesn't take much web searching to find stated problems with the ball type grippers, and that was what started my rethinking them. I was able to keep the outer cylinder that had the ball cage inside it and use the ramp in it to close the fingers on drawing in the tool holders, so the only changes I made was to replace the ball cage and balls with he fingers and add a shoulder bolt to the bottom of the draw bar to array the fingers around.

Attachment 262580

Bob