R8 collet

[rzw0wr]

I have some cheap R8 collets that came with my machine.
They are new however they let the cutter slip under a heavy load.

Is this normal for a collet?

What is a decent collet to buy?

Thanks,
Dale

 

[ddillman]

That is not normal

 

[OTmachine]

Not normal. Hardinge collets are Good!

 

[ThinWoodsman]

Again, not normal. I haven't had any problems with TTC collets from Travers.

 

[RJSakowski]

How much torque are you using on the drawbar? 30 lb-ft of torque is recommended by Tormach for the their machines with 40 -60 lb-ft for more demanding work.

 

[projectnut]

How much torque are you using on the drawbar? 30 lb-ft of torque is recommended by Tormach for the their machines with 40 -60 lb-ft for more demanding work.

Bridgeport is similar recommending 40 ft. lbs. on the drawbar. Keep in mind the largest end mill Bridgeport recommends using is 3/4". I have used up to 1 1/4" end mills in an end mill holder, but that was for plastic or aluminum.

 

[Buffalo21]

The biggest problem I’ve had with collets, is either the collet or the shank of the end mill are not clean, no oils or grease on either surface.

 

[Bob Korves]

It is possible that your drawbar threads are bottoming out in the collets before tightening on the work? Something as simple as a spacer washer under the drawbar, decreasing the effective length, can cure the problem.

 

[Tozguy]

What do you mean by 'heavy loads'?

 

[yendor]

You say they are NEW - is there a chance you didn't clean them on the inside contact surfaces and they have protective OIL from the Mfg for storage & shipping that needs to be removed.