Key Slot On R8 Collets...?

[EmilioG]

I have some r8 collets that have the slots a bit dented and dinged a little.
Does this affect the collets accuracy much? When do you throw them away for
a new one? The collets I own aren't too badly worn but would like to know
if and when it becomes a problem. Thanks

R8 BP Mill collets w/ 7/16"-20 threads.

 

[Franko]

I would doubt that the grooves affect accuracy at all. R8 collets have two tapers, one on the upper and the other on the lower. I think all the groove does is keep them from slipping.

 

[RJSakowski]

I agree with Franco. As long as the ding hasn't created a burr on the upper cylindrical surface, you are OK. If there is a burr, you can remove it by hand with a stone or dress it with a grinding wheel in a Dremel. Nothing precision involved, just make sure the are no protruding surfaces.

 

[OldMachinist]

Stone off any burrs that protrude larger than the diameter and use as normal. I've seen R8 shanks that had grooves all the way around from spinning against the key that still run true once any burrs were removed.

 

[EmilioG]

Thanks. Nothing major, just some dings and dents on the key slot. I used a small file to remove any
small burrs. Same with R8 jt3 arbor. I have a good old USA Jacobs and would like to keep it. Thank you all.

 

[chips&more]

Someone said and someone agreed a R8 tool holder has two tapers? No, sorry. A R8 has two reference points, the one taper at the business end and the journal on the back end where the draw bar threads are. The key way only prevents spinning. Any burrs along the keyway big enough to get in the way, will affect collet accuracy. Some people even take the pin out of the quill/spindle so no need to align the pin to keyway and stops keyway damage. But, then I would think you risk spinning…Good Luck, Dave.

 

[EmilioG]

 

[Franko]

Oh heck, made a fool of myself again. After I posted that I knew I should have gone and looked at one. I just remembered there being two shiny smooth surfaces that do all the indexing. I was slightly mistaken.

 

[RJSakowski]

Oh heck, made a fool of myself again. After I posted that I knew I should have gone and looked at one. I just remembered there being two shiny smooth surfaces that do all the indexing. I was slightly mistaken.

We all make mistakes. The important point to convey is that the taper and the cylindrical sections are the critical reference surfaces and any burrs in either area will destroy the accuracy of the collet.

 

[darkzero]

I could care less about the key way on a R8 collet or arbor. I removed that stupid R8 pin on my mill. Tool/collet changes are so much quicker now. Spinning the taper is not a concern or problem for me.