# Key Slot On R8 Collets...?



## EmilioG (Apr 7, 2015)

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 (Apr 7, 2015)

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 (Apr 7, 2015)

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 (Apr 7, 2015)

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 (Apr 7, 2015)

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 (Apr 7, 2015)

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 (Apr 7, 2015)




----------



## Franko (Apr 7, 2015)

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 (Apr 7, 2015)

Franko said:


> 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 (Apr 7, 2015)

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.


----------



## george wilson (Apr 8, 2015)

I also removed the blasted  pin on the mill at work. No trouble with any R8 collet ever spinning. We were careful to keep OIL out of the hole!!

I had gotten a used right angle attachment for the mill,and it had a very worn R8 shank on it. The pin had worn into the R8 shank sideways quite a bit. About 3/8" ,if I recall,before we ever got the unit. Well,the right angle head got royally stuck since the pin was way to the side of the groove. It could not be gotten loose!!

After we finally DID get it loose,I took the pesky pin out,and never regretted it.


----------



## c--line (Jan 30, 2021)

EmilioG said:


> View attachment 99143


Thanks for the specs. regards, c--line


----------



## Buffalo21 (Jan 30, 2021)

darkzero said:


> 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.


My Rockwell vertical mill and my early 80s mill/drill, never had the pin to begin with.


----------



## MrWhoopee (Feb 24, 2021)

This thread has reminded me that I need to remove the pin in my spindle. It's been buggered up ever since I got the machine and I curse it every time I change collets. Useless as neuticles.


----------

