Broken R8 Collet ???

I have an ER-32 collet with a crack:
cracked_collet.jpg

I was picking up some used ones to try and complete my set.
When the seller saw the cracked one he pointed it out gave it to me free.
I have never used it.

I figure it was either dropped onto concrete, or more likely, used to hold something smaller than its specified range and collapsed too far.

brino
 
Trying to mount a smaller than range tool would result in compressive forces and shouldn't cause a fracture like that.

It may have been cause by improper insertion of the collet in the the nut. If someone inserted the collet in the chuck with an endmill mil in place and then the nut tightened, the unbalanced forces could cause a fracture like that.
 
Could be some swarf got into the slot between fingers and, being incompressible, put too much strain on the web when tightened.

Tom
 
Collets flex each time they are used. They get tired. I know that our machines with ER32 collets recommend replacing them every year when used in production.
 
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