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5C "Emergency" collet sticking in spindle

dkmc

Diamond
Production deburr job on Speed Lathe, 5C soft "Emergency" collet starts sticking in the spindle, gets to the point it sticks enough that you end up banging very hard on the lever closer to get it to release :angry::angry:

I've tried everything from relieving the head angle at the slots to spreading it with a tapered pin (which works for awhile), to synthetic grease on the head angle, but it still sticks after 10 minutes or about 25-50 closings.
I know if it was hardened it would keep its spring, but this is soft.....

Any ideas appreciated.....

dk
 
One simple thing: Are you over tightening it with the closer? A lever closer has a lot of leverage, and it's easy to dial way more clamping force than you really need. For a deburring job, you shouldn't need much.
 
Well, you said "Any ideas" :D

Rev up your hot glue gun. Inject glue in the slots and holes of the collet. Let it cool and trim off the excess with a sharp knife. Hopefully the springiness of the urethane might be enough to help push the sections apart when released.

I originally did this as a method to keep brass chips from getting into the collet while the lathe was in operation and it worked quite well. I did not have a problem with collets sticking in the chuck.

Perhaps in your circumstance you might try to preload the urethane by putting something just a little bit oversize in the collet to spread it just that wee bit extra before injecting the hot glue.
 
Steel collet.....
Friend gave me another one, that stuck from the git-go.....so I polished it
with scotch bright (did all that to the other one also) and it still stuck a bit but better than prev one.
Worked OK for awhile....

So then.....when it started to stick every other part, I polished again, then I mixed up a concoction of a bit of Never Seize, Greased lightning (Teflon) oil additive and Castrol Moly-Dee.

Painted it thinly on the head angle and it went about 3 hours without sticking. Can't try it on the old collet, cause I hammered it oval and threw it in the scrap barrel. That one caused me too much wasted time to keep it around.
 
I can't say this is right, but I have seen old timers use a die grinder and grind an X on the angled faces of the collets where they seat against the spindle. They say the air that gets in the groves keeps them from sucking stuck due to vacuum?

It has worked for them every time that I have seen.
 
They say the air that gets in the groves keeps them from sucking stuck due to vacuum?

Interesting if not a bit humorous......;)

I don't think it's trapped air, but we used to grind flats on the slots on the head angle (if you can follow that) on hardened collets used in production fixtures on the shop floor at Hardinge.
But the soft Emergency collets have always been a problem.

It's possible the "X" relieves the binding on the head angle......the soft ones
always 'mark up' with shiny spots on the head angle where they contact....and bind.

dk
 
collet

I have sprung collets by driving a tapered shaft in them to make them open up more. I have used the taper of a punch with a tapered shaft. I just put collet on bench and pushed taper into bore till they opened up about .03 more then bored dia.
Jim
Also done this with hardened collets .
 








 
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