Strange R8 Collet Problem.

I had the opposite problem; all the collets that came with my mill fit fine but the R8 drill chuck spindle I bought on ebay didn't. It was slightly oversize right along the keyway; a friend chucked it up on the lathe and lightly polished it until it was the right size.
 
rdsii64 said:
This is something I failed to look at. After re-reading you post, this sounds more plausible since the top of the collet measures .949 (My caliper actualy measured it at .950) It looks like I will be chucking a drimmel attachment in my drill chuck and SLIGHTLY open up the keyway and see if it works.
first I'll measure the keyway in my R8 drill chuck since it goes in and comes out properly, and If I find a difference, I'll match then with my dremmel atatchment.
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Use bluing to find exactly where the interference is. If you don't have bluing, a blue Sharpie will work. The keyway may be too narrow or too shallow.
 
You can also use the shank end of a 5/32 (.1562) drill bit to see if the slot is wide enough. Just run it up the slot to see if it hangs up somewhere.
 
I just got home from work and measure the key way depth of my collets and compared them to the key way depth of my R8 drill chuck. The drill chuck is deeper. The Key way on my 5/16 collet is .094 and my drill chuck is .134 deep.
 
Have you checked the width of the slot yet? Was there a tight spot ? From what I saw a depth of .094 is in spec. So if it is the depth causing the problem then the pin in the spindle is sticking out more than it should and you would have problems with many different collets made.
 
Billh50 said:
Have you checked the width of the slot yet? Was there a tight spot ? From what I saw a depth of .094 is in spec. So if it is the depth causing the problem then the pin in the spindle is sticking out more than it should and you would have problems with many different collets made.
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We had a problem with the key on a Grizzly G0755 mill at work. The pin was a set screw which worked its way deeper causing an interference. I machined the tip of a socket head cap screw and inserted it instead. Now it cannot work deeper and the crew can be tightened against the spindle wall instead of floating.

To access, I lowered the quill and was able to reach the spindle through a slot in the quill.

Or once you remove the offending pin, you can just leave it out.
 
I just thought it would be a good idea to check width before possibly doing something that didn't really need to be done. I always check everything first. If collet is within specs then yes I would either remove pin or fix it. I don't like removing pins because I had a drawbar gall up in a collet once and the spindle pin was removed. Had a heck of a time getting the collet and drawbar out.
 
Billh50 said:
I don't like removing pins because I had a drawbar gall up in a collet once and the spindle pin was removed. Had a heck of a time getting the collet and drawbar out.
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Good point! That may have been the original reason for keying the spindle.
 
darkzero said:
Or better yet, take that stupid thing out!
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Agreed; I had a Induma Vertical mill, more or less Bridgeport style, (Italian) where the pin was sheared off and the rack gear teeth were broken, so ordered a new quill and also the pin; I refitted the quill, and replaced the pin, and it was only a very short time that the pin sheared off again, and was never replaced (or needed) again; that was about 25 years ago or so, and it was never missed. One has to disassemble the spindle from the quill to accomplish replacement.
 
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