We change a LOT of tools using the ATC. Some may remember the photos of worn TTS tool holder ends I posted. Speculation was that the tool holder were just soft to start with. Checked using our Rockwell Bench Tester however they were all Rc 50+. We just change a LOT of tools.

One problem that has raised it's head now and again is the breaking of the nylon bolts holding the ATC fingers - dropping the tool and stripping the fingers off the tray. After a while inserting new bolts becomes almost as fast as manually changing tools (well maybe not that fast) but it is still a pain in the ass and tends to chip carbide tools. I also noticed that once it started on a particular tool position, it became more frequent. Looking closely during tool change it was apparent that the tool holder was being pushed in and out by the descending spindle due to misalignment. So the tray would be realigned, helped for a while but the problem would return. Finally noticed that the nylon fingers no longer held the tool holder tightly. The offending ones were just worn out. Replaced with new fingers and problem solved.

Attached are photos of two worn fingers and a new finger. You can notice the white stress marks on the finger around the hole for the toolholder and the holder doesn't fit snug in the finger any longer. It has about 1/16" of play.

I think that the worn fingers may be capable of being heated, closed up and rebored to correct size and location. But for now I have just replaced then with new. So far I have replaced 6 of the 10 fingers. Happy to say that once the finger is replaced the problem with breaking bolts at that location goes away.

Hope this helps someone.

gary