How can I pick & choose a new Sherline 3-jaw self-centering chuck?

[cazclocker]

Hey guys - I need to replace my #1041 Sherline chuck (the 2-1/2" diameter with 3/4"-16 threads) because my old one has runout that is unacceptable. I've dismantled, cleaned & oiled it at least twice now, and the chuck still throws a piece of drill rod more than .006" measured 2" away from the jaws.

How can I acquire a new one (same model) and be assured of better runout specs? I'll have to order online because there's no local dealers. It seems awkward to contact one of the sellers and say "hey would you sort through all your inventory and sell me the best one". I'd hate to resort to that.

I guess Sherline chucks are "built to a price point", meaning I can't expect the specs I might get from a higher quality brand.

PS - if I can find an acceptable #1041, I'll keep my old one and try to stone the jaws until I get better TIR. I've never tried that and I expect it will be a tedious, trial-and-error project. If I succeed, I'll keep it as a backup. If I botch it - well, I have room for it in the circular file (cringe!).:angry:

 

[cazclocker]

Input, anyone? Should I contact Sherline themselves..?

 

[Bill C.]

Input, anyone? Should I contact Sherline themselves..?

I found this web-page http://www.sherline.com/1040inst.htm They say run out is between .002 and .003 for a three jaw chuck. But .006 is in my opinion way to much. They said if less run out is required to use a four jaw chuck. Sorry

 

[cazclocker]

I found this web-page http://www.sherline.com/1040inst.htm They say run out is between .002 and .003 for a three jaw chuck. But .006 is in my opinion way to much. They said if less run out is required to use a four jaw chuck. Sorry

Thanks Bill. I probably should have mentioned that when I say "unacceptable runout", what I mean is that the jaws fail to hold things parallel to the bed ways. In other words, a piece of drill rod (for example) is somewhere close to the chuck's center right at the point of the jaw's ends. But further out from the jaws, the piece veers off to the side by about .006", measured 2" from the jaw's ends. I'm not really sure if what I'm describing is correctly called runout or not. I can live with a chuck that may hold a piece within a few thousandths with successive chuckings, but I really want the workpiece to be held square to the chuck, and parallel to the lathe bed ways.

Is what I've described called "runout"? If not, what's it called?

Thanks,
...Doug

 

[mikey]

Doug, you can send your chuck to Sherline for evaluation and they will advise you on whether you need to just change the jaws or perhaps replace the chuck. 0.006" of run out is way too much for this chuck. Either you have some significant damage or perhaps you might want to recheck it with a precision-ground rod or dowel pin after being sure the chuck jaws and pin are oil-free.

My experience with Sherline's chucks is fairly good. I just checked my 15+ year old 3-jaw with a 3" long, 3.8" OD dowel pin at 100 RPM and got less than 0.0005" run out (it's about 0,0004") at the end of the pin. While this is not great it is pretty good for a sub-$200.00 chuck that has seen a lot of use. My 4-jaw scroll chuck has similar run out so its possible you got a bad sample.

 

[wwunder]

Could you buy a taig three jaw chuck with aluminum soft jaws? Bore them out and they will be perfect. That's what I did when I had a craftsman 109 lathe.

 

[mikey]

It appears that some posts have disappeared from this thread - Bernie posted about grinding the chuck jaws and referenced another post on HM about this subject. Hopefully, Bernie will post that again.

Doug, I'm not sure how old or how used your chuck is. If the chuck is fairly new or in very good shape and the jaws were somehow "sprung" from clamping something at the jaw tips then maybe a light grinding them might work. This assumes there is no significant wear in the scroll threads of the chuck body or the back of the jaws or the lands on the sides of the jaws. It also requires a tool post grinder, a jaw-loading ring and the ability to pull the jaws into parallel before grinding. If you do this then you might reduce run out in the single area that the jaws were in when you ground them but it may not be so in any other area of the chuck. Just something to think about.

I'm sure you're aware that if Sherline determines that the chuck jaws are the issue they will hand-match a new set of jaws to your chuck to bring it back into specs.

Good luck!

 

[itsme_Bernie]

Hah hah! I thought something was wring with the server! I can't remember exactly what I said, but one of our trusty moderators, 8ntsane, did repost his pcs of the chuck-jaw grinding plate he made, in the original thread.

I wonder if that is still posted?
Let me try to find it again

Bernie

 

[Lee in Texas]

FWIW- Bison makes a new 3-jaw chuck to fit Sherline. At $350, it's not cheap, but it may be what you're looking for.

 

[D.C.Clark]

Thanks Bill. I probably should have mentioned that when I say "unacceptable runout", what I mean is that the jaws fail to hold things parallel to the bed ways. In other words, a piece of drill rod (for example) is somewhere close to the chuck's center right at the point of the jaw's ends. But further out from the jaws, the piece veers off to the side by about .006", measured 2" from the jaw's ends. I'm not really sure if what I'm describing is correctly called runout or not. I can live with a chuck that may hold a piece within a few thousandths with successive chuckings, but I really want the workpiece to be held square to the chuck, and parallel to the lathe bed ways.

Is what I've described called "runout"? If not, what's it called?

Thanks,
...Doug

Doug,

What you describe doesn't sound like runout at all to me. It sounds like the axis of rotation of the headstock is not parallel to the travel of the cross slide. It that is the case, you will cut a tapered cylinder. Chuck up a piece of stock a few inches long and take a cut. Mike the diameter at the beginning and end of the cut. If it is not the same that clinches it. Even with the alignment key in place, it may be possible to adjust parallelism a few thou. Also make sure that that the alignment key is installed with the ground sides of the key against the sides of the slot.

You don't say how you measured the veering off. The way to do it is with an indicator in the tool post.

Further checks: Indicate the drill rod in a collet, a well-centered 4 jaw chuck, and the 3 jaw. Are the results similar? Rotate the spindle by hand. Does the rod wobble?

"Self centering chuck" is a very misleading term. None of them are. They are not intended to be a centering datum. They are intended to be a way to quickly and firmly hold a work piece. If your work piece requires two or more coaxial diameters, and you use a 3 jaw chuck, you must cut each diameter in the same setup, without loosening the chuck. If this can't be done, you must cut the first diameter, then center on it in a 4 jaw to cut the others. Or, hold the first cut diameter in a collet.

For more on headstock alignment Google "Rollie's Dad's Method".

Finally, here's a fixture I've added to my Sherline to make and hold a very accurate spindle alignment.

Best regards,

David Clark in Southern Maryland, USA