R-8 Spindle Key

rakort

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I'm about ready to assemble my spindle for my mill. I have acquired and installed a new set screw for indexing tooling into the R8 spindle. I've read a number of things regarding whether or not it's a good idea to have this in the spindle and want to hear what other may offer regarding this

thanks
Brian
 
In my first R8 machine the screw was broken off when I got the machine. I used it that way for a long time. My second R8 machine, same brand and type, has an intact screw. So I have used both ideas on the same basic machine. In reality, both have benefits and problems. I am equally happy with using them either way. It is certainly not worth it for me to take the spindle apart to fix or remove one of those pins. In my opinion, decide for yourself. The only thing I would never accept is a spindle with a screw that has the tip broken off and that still sticks out into the collet space, even a tiny bit. That will cause gouging of collets and wedging of collets out of proper alignment, causing inaccuracy and damage to tooling. Regardless, your choice is reversible either way if it turns out you don't like it. The important thing is to be conscientious about cleaning and getting the oil and crud off the tooling and spindle, tightening them properly every time, and trying really hard to never crash your machine and spin the R8 tooling in the spindle. R8 is not that secure of a mounting system. Don't push your luck. No good (and much bad) can come of it...

I used to fly an aerobatic single seat aircraft that had a placard on the panel that stated: "Don't try anything stupid." We should post that on our machinery as well...
 
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if you have it apart anyway, I would put it in. I have had problems getting a collet out of bridgeports because someone tightened up a collet with chips in the threads. The drawbar bound up and the collet just turned when trying to loosen. It can be a real pain in the a$$.
 
if you have it apart anyway, I would put it in. I have had problems getting a collet out of bridgeports because someone tightened up a collet with chips in the threads. The drawbar bound up and the collet just turned when trying to loosen. It can be a real pain in the a$$.

Shars sells a collet wrench for just that problem. #202-5596 I have never used one but think I will order one just in case. I pulled my pin when I got my PM935 mill.

Mike
 
My old RF had a pin, and since it was my first mill, I thought thatwas the way it was supposed to be. My current Rockwell doesn't have one, and I wish it did. I have a couple of collets that don't thread up nicely, even after chasing the threads on the drawbar.

The wrench from Shars looks like a winner!
 
I can't imagine (I know, others do it) running an R8 collet without a pin. Won't the collet spin as you try to tighten it?
 
My R8 mill doesn't have one and I've never had a collet spin, maybe lucky. My Hardinge lathe has the spindle machined for 5C collets and has the pin. Its old and has seen a lot of use before I got it. Because the collets always go in with the same orientation you can feel a slight 3 sided wear pattern in the bore. Without the pin I wonder if the wear would be more even.

Greg
 
I can't imagine (I know, others do it) running an R8 collet without a pin. Won't the collet spin as you try to tighten it?

It does, unless the drawbar goes in easily. I have to set the collet up into the spindle, and snug it up by hand. Once it's there, I can apply the spindle brake, and use the drawbar wrench.
 
no big deal to stick a bolt in the side on my mill if it spins, haven't needed to ever...

peens.jpg
 
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