What makes ER collets good quality?

[Susquatch]

I've used these Collet Nuts with internal bearing for decades.

Can you take the nut off for us and take a photo of the bearing? No rush. I'm just curious about it cuz I've never seen a nut with a bearing in it.

 

[StevSmar]

…original ETM nuts.. Haven't noticed any problem with the collet spinning or concentricity.

Thanks for letting me know you’ve had good success

They’re pricey in the ER40 size!
ETM 4513028 ER40 Collet Chuck Clamping Nut

 

[eotrfish]

Can you take the nut off for us and take a photo of the bearing? No rush. I'm just curious about it cuz I've never seen a nut with a bearing in it.

Sorry - mine don't come apart. I did find this rendering on Ali that shows how the Chinese knock-offs are assembled.

 

[Susquatch]

Sorry - mine don't come apart. I did find this rendering on Ali that shows how the Chinese knock-offs are assembled.

Oh my! I'm sure glad you didn't take it apart! Cuz that's not what I meant at all. I meant to take it off the arbour and remove the collet and try and take some inside photos. If I had a bearing nut and someone asked me to take it apart for them, I prolly wouldn't be as polite as you are!

I get the drift from the Ali photo though. Looks like there is only a flat ball bearing between two flat races in there. This begs the question of how concentricity is maintained.....

I assume the reason for the bearing is to facilitate additional tightening torque on the nut and thereby tighten the collet taper better.

I also assume that's only meaningful with big endmills, because you run up against the maximum holding limits of the R8 taper and pin itself at some point. But of course, that assumes its R8 and not 40 or whatever.

Very interesting! Thanks for digging up the photos. Much appreciated!

 

[DPittman]

Oh my! I'm sure glad you didn't take it apart! Cuz that's not what I meant at all. I meant to take it off the arbour and remove the collet and try and take some inside photos. If I had a bearing nut and someone asked me to take it apart for them, I prolly wouldn't be as polite as you are!

I get the drift from the Ali photo though. Looks like there is only a flat ball bearing between two flat races in there. This begs the question of how concentricity is maintained.....

I assume the reason for the bearing is to facilitate additional tightening torque on the nut and thereby tighten the collet taper better.

I also assume that's only meaningful with big endmills, because you run up against the maximum holding limits of the R8 taper and pin itself at some point. But of course, that assumes its R8 and not 40 or whatever.

Very interesting! Thanks for digging up the photos. Much appreciated!

Here's a picture of the inside of my colet nut. My holder is a "Oz 25" but I think all collet holder nuts are similar?

 

[thestelster]

Oh my! I'm sure glad you didn't take it apart! Cuz that's not what I meant at all. I meant to take it off the arbour and remove the collet and try and take some inside photos. If I had a bearing nut and someone asked me to take it apart for them, I prolly wouldn't be as polite as you are!

I get the drift from the Ali photo though. Looks like there is only a flat ball bearing between two flat races in there. This begs the question of how concentricity is maintained.....

I assume the reason for the bearing is to facilitate additional tightening torque on the nut and thereby tighten the collet taper better.

I also assume that's only meaningful with big endmills, because you run up against the maximum holding limits of the R8 taper and pin itself at some point. But of course, that assumes its R8 and not 40 or whatever.

Very interesting! Thanks for digging up the photos. Much appreciated!

I believe all bearing nuts will look to have two parts looking from the front, and the purpose, I believe is so that when you tighten the outer ring, the inner ring which bears onto the front taper of the collet doesn't rotate with the outer ring. So less wear on the collet and collet nut, and collet chuck pocket, and possibly more even clamping forces.

 

[thestelster]

Also, collet nuts are consumables, and should be replaced at some point.

 

[Susquatch]

I believe is so that when you tighten the outer ring, the inner ring which bears onto the front taper of the collet doesn't rotate with the outer ring. So less wear on the collet and collet nut, and collet chuck pocket, and possibly more even clamping forces.

Didn't think about collet and nut wear. Makes GREAT SENSE. Way more sense than just tightening force.

 

[Susquatch]

Here's a picture of the inside of my colet nut. My holder is a "Oz 25" but I think all collet holder nuts are similar?

My ERs are very similar. I was wondering about the nuts that have bearings. But I think my curiosity is satisfied.