VTC Spindle Pop

The spindle in my VTC unexpectedly dropped the tool on the table with a popping noise last thursday. Afterwards it sounds and acts differently. For instance, it doesn't brake when the M5 command is given and doesn't properly release the tool during tool changes. Has anyone experienced this? I'm guessing there is something amiss with the retention fingers, or the associated mechanism, but I'd like to get some opinions before diving in. Any thoughts are appreciated. Thanks for your time.

It sounds like your beveled washers have busted or the collet fingers themselves. either way you most likely have to pull the spindle out to repair.

No Fun,
Is there any way you can check tool retention.
Possibility at least puting a tool holder in the spindle (clamped) and try to pry the tool out with a screw driver. Tool retention should be approximately 2000 lbs for a 40 taper and 4 to 5000 pounds for a 50 taper. If you can remove the drive keys, clamp a tool holder in the spindle and try to turn the holder in the spindle. Even with the "drive keys" the taper should lock up tight. If you can turn the holder in the spindle you have bad bad retention problems.
Seems like the belleville springs will work and flex a million times but, If a tool holder "pop" out one time and the drawbar is allowed to "snap" up or back, that is when the springs get busted.
The drawbar can only move as fast at the unclamp cylinder will allow it to move. When a toolholder comes loose or a retention knob breaks, snap it goes and the springs seem to get all the shock.
Let us know and stay in tough.
Regards Walt...

I went back to edit what I wrote, that didn't work somehow.
I am going to try to correct my mistakes in this post.
I ment to say, remove the drive keys, clamp a tool in the spindle and with the drive keys removed, the taper should lock up the toolholder.
Last line, I ment to say stay in touch...
Regards Walt...

You left off one point. You said it does not brake when an M5 is given. That seems to be a problem with the spindle controller.

Regards,

Chippy

Google Clamprite for draw bar force guage to checking clamping force.

I you are going to recommend clamping gages. Consider Command. If you contact your Command Tool Salesman and he will have the details.
We use them all the time and are very satisfied with their performance.
Regards, Walt...

I recommended Clamprite because they are cheap. Maybe he would like Forcecheck better: it is electronic.

Command is electronic also.
Regards Walt..

Have you stuck your head in and put the mark one eyeball on it.

I broke a retention finger off of a 5800 Hor recently and changed it out relatively easily. The parts price had the typical extra 0 on the end, so it was pricey. We did from the taper end didn't have to remove anything but the draw bar. It took longer then it sounds like it should had to jiggle and jury rig. Not sure if the vtc is the same but I'm gonna look tomorrow. Shouldn't have to jerk the spindle for a simple somewhat normal occurrence.

a comment

If you go in there and replace the bellville springs or other stuff, make sure you have a proven procedure for doing it! This varies with machine type, but I've heard of torches being required in certain scenarios. Mazak tends to have internal service bulletins covering such procedures.

I can state with certainty that the Mazak New England Tech Center would provide all the procedures and diagrams you may need for this job, along with tireless phone support. I've seen them do it!


-Jim

PS - M5 not working properly is spooky and speaks to spindle controller issues as mentioned above.