slipping collet!!!

[gibl5s]

Has anyone ever experienced a bit running out of the collet while cutting afile? I saw the problem and I put a new collet on the spindle and thought that had fixxed it but it did it again. I put a micrometer on the bit to see if it was worn but it wasnt. Just kinda worried about this happening again.
anyone ever had this problem?

[Ger21]

I've been using big italian machines for almost 20 years, and have never had a bit come loose. And we cutt at 1200ipm (20i/s) full depth through 1" thick materials.

If you have bit's coming loose, there are only a few things that it could be.

1) It's just not tight enough. I think this is the culprit in the majority of cases.

2) defective collet

3) collet not installed in the nut correctly

4) bottoming the bit out in the collet

[gibl5s]

Thanks so much for your reply Gerry. Tell me this, I have read that the collet should not be tighten real tight in order to not do damage to the collet. What do you say?

[scottp55]

Perry, Gerry is on the money! Most likely is # 3 & 4.
Hope you threw the bit away also.
If possible, position your wrenches so a VERY firm 1 hand tightening is possible. If I have to struggle with 2 hands to get it off--I KNOW it was too tight. You disassembling collet and nut at every tool change and blowing out or brushing material out of both them and the spindle?

[Ger21]

At my current job, we use a torque wrench to get the proper tightness.
At my previous job, we just cranked them very tightly. These were ER32 collets, and I've never seen once get damaged. I honestly think you'd have a hard time causing damage from over tightening. From my experience, people tend to under tighten far more often than over tightening.

[Brady Watson]

...we use a torque wrench to get the proper tightness.

Yup...but few will ante up for the setup. It ain't cheap. I'm pretty sure Techniks has them.

-B

[Burkhardt]

Good article from Tormach about collet slip. More oriented towards draw bar collet types but interesting ideas about what to lubricate and what to keep dry.

Maybe the problem happens when the nut is insufficiently lubricated and most of the torque is needed to overcome the nut friction (or seizing) and too little is left to wedge the collet into the taper.

[Ger21]

Yup...but few will ante up for the setup. It ain't cheap. I'm pretty sure Techniks has them.

-B

Neither are a dozen HSK63 tool holders.

[Bob Eustace]

Here is the link to Brady's suggestion - brilliant idea and coupled with the thrust washer nut you'd end up with the perfect system.

http://www.techniksusa.com/metal/torque_wrench.htm

[Ger21]

That's the wrench we use.