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Jacobs spindle nose lathe collet chuck

DAN Z

Aluminum
Joined
Mar 18, 2005
Location
RI
Hi All,
I just bought this chuck with a full set of the rubber collets. No more frustration of not have a collet for the odd diameter. Mounted it on my 10ee (1942) chucked a 1/2" dowel pin in the collet and got .025" run-out for a reading!!! pulled the rubber collet out and took a reading on the cone...020" reading, rotated it in all 3 positions the same .020"! is there an adjustment that can be made? Can I regrind the cone while mount on the lathe?? How could it be so far off?
Any thought on saving this chuck will be most appreciated.
Dan
 

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Cal Haines

Diamond
Joined
Sep 19, 2002
Location
Tucson, AZ
Check the taper on the back of the chuck for a chip or burr.

Chuck a large pin in your 4-jaw and dial it in as close as you can. Then use a collet in the Jacobs chuck to grab the free end of the pin, so that the chuckis facing the headstock, with the D1 pins facing the tailstock. Check the chuck's taper with an indicator and see what you can figure out.

Cal
 

DAN Z

Aluminum
Joined
Mar 18, 2005
Location
RI
Thanks all,
A little humility to share, I did find the manual which gave me some time to think. I remount the chuck; the manual says I should have .004" between the face of the spindle and the back of the chuck before tightening. While checking this measurement I started to think about the socket cap screws holding onto the D1 pins. Sure enough one of the screws was projecting a little beyond the back of the chuck. Eureka! Remounted and the chuck was within a .001 or .002. I did find some of the rubber collets were truer than others. I was already to get tough with the seller, but the good machinist never jumps to conclusions! I had used one of these chucks years ago happy to have one in my possession again.
As always this forum is a great resource, thanks
Dan
 








 
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