Replacing old Collets

[RaisedByWolves]

I put better in quotes - because objectively it holds better, with far more contact area. But to do this, on an ER40 collet you need to apply 90 - 130 foot pounds to tighten it. Most people don't tighten them enough, and so they don't seem to work 'better'... Your mill needs a good brake or you need an adapter with flats so you can use 2 wrenches.



In fact from an engineering perspective, ER collets win in every way. *IF* they are properly tightened. BUT I still use my E8 collets. Habit. Comfort. But not because R8 is better, because it is not.

For proper tightening, see https://www.shars.com/media/manuals/clamping-torque.pdf

There are many other sources that all agree with these numbers.

Better is a subjective term. Are you talking holding power? Ease of use? Grip Range?


Also curious as to why are the bearing nut torque values higher than the others?

This seems backwards to me, but I never would have thought, or even been able to torque them that tight with conventional wrenches.

After looking at this and thinking a bit, it doesn't say anything about holding power from one nut style to the other either. Seems more like recommended max torque values irrespective of holding power.

Not trying to argue, just looking for info as Im now using these after years of avoiding them. We had/have ER40 collets for one of our machines that never get/got used as we had nothing but trouble with endmills pulling out. We would have had to beat the wrench with a hammer to ever see 130ftlbs on those.

Then again that was long before the internet where you could easily look up everything.

 

[Dabbler]

We would have had to beat the wrench with a hammer to ever see 130ftlbs on those.

All the commercial wrenches are too short in my opinion. I made mine to accept a 1/2" torque wrench to hit above 120lbs. I've never had an end mill pull out. I just like the R8 more...

The contact area on the ER40 is many times more than on an R8, and that is why the high torque is required. To hold the end mill securely, the torque has to be right. In Europe it is common practice to use a torque wrench to tighten an ER collet.

 

[sdelivery]

I think you would be better off with a power drawbar. Your R8 collets will hold better because they will be tight enough.
It can be tough to wrench the drawbar while holding the brake while trying to maintain balance. Maybe you can find a used setup?

 

[COMachinist]

I bought a set new Vertex R8s they are nice! There is so little run out in my PM935TV mill it is't worth mentioning. Less than 6 or7 tenths on these collets. By my Sterrett dti. I have a R8 Er40 Collett chuck and the Tormach TTS system with their 3/4" special Collet. I have less great experiences with the ER40 holding end mills secure I even bought one those realy high grade bearing lock nuts, ie expensive. They do work good when they work, but you never know when they won't. The PM935 has a power draw bar on it and that makes it easy to change tooling with R8s.
CH