VF3 tool change problem

[cata1351]

When changing tools this morning, the spindle picked up the tool from the carousel, but the tool did not get pulled completely up into the spindle. The tool was hanging out of the spinldle about 1". Just kind of dangling from the pull stud. Then the spindle turned on and was getting ready to start milling. The operator noticed the problem and shut the machine down before any damage was done. Any ideas as to why the tool would not have been pulled all the way up? We checked the taper, there were no chips wedged in, nothing appered to be wrong. We unclamped the tool, and have since made several succesful tool changes with no problems. Ideas???

[Geof]

We had a VF0 do this running unattended on a long cycle job. I came to the conclusion that the tool had moved in the carousel due to the vibration from a heavy cutting sequence that had the whole machine shaking. On a couple of occasions previously it had dropped a tool during the tool change and when I checked I found a few tools had moved forward in the fingers in the carousel. Needless to say all hell broke loose when the tool hit the job and jammed sideways in the spindle running at 7500rpm. We could see that it had been gripped with balls in the gripper riding on the rim of the pull stud not down on the angled faced and we could see the grooves they made as the tool was pushed sideways. The spindle taper was damaged so we took the machine off regular production and just use it for rough work now. But in two years since then it has never missed another tool change and it has done thousands.