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Gripping Smaller Stock

jephw

Aluminum
Joined
Jul 23, 2020
Good morning folks.
I am looking for an efficient way to grip smaller stock in our machine for small quantity jobs. We run a Mori Sieki NL3000 mill turn with a 15" chuck. Every now and then we get orders for parts that require smaller stock, like 1.25" and down and gripping anything smaller than 1" is a challenge.
I am exploring the option of getting a smaller chuck, 6 or 8" to grip in the 15" chuck and clamp my stock that way. Would that be a safe way of doing these kind of jobs?
Are there other options anyone can suggest?
Any information is appreciated.
 
That's pretty typical, you can find lots of Youtube vids of big chucks holding small ones. Among other things it gives you an "Adjust-Tru" capacity if the large chuck is a four jaw.

Another option is a cylindrical 5C collet adapter in the big chuck, they're around 3" in diameter. Not the same holding power as a chuck perhaps, but for small rod stock hard to beat.
 
First thing that comes to mind is a collet chuck. I have a nice 16C collet chuck that will grip up to 1.625 diameter. After that, I have to go to the chuck. You can swap back and forth within about 5 minutes.
 
That's pretty typical, you can find lots of Youtube vids of big chucks holding small ones. Among other things it gives you an "Adjust-Tru" capacity if the large chuck is a four jaw.

Another option is a cylindrical 5C collet adapter in the big chuck, they're around 3" in diameter. Not the same holding power as a chuck perhaps, but for small rod stock hard to beat.
It's a 3 jaw chuck but tolerances aren't too tight on most parts, 0.002 is all. Also, research I've done shows the smaller chucks are usually a little cheaper, so I'll probably go for that. Thanks for your input.

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First thing that comes to mind is a collet chuck. I have a nice 16C collet chuck that will grip up to 1.625 diameter. After that, I have to go to the chuck. You can swap back and forth within about 5 minutes.
That would be a perfect setup if those jobs would be big orders. But generally small quantities.
Thank you for the information.

Sent from my moto g(7) play using Tapatalk
 
That would be a perfect setup if those jobs would be big orders. But generally small quantities.
Thank you for the information.

Sent from my moto g(7) play using Tapatalk

Help me out here. What would the size of the order have to do with ease of holding small diameter work?
 
I do not understand the question. Is there a problem making soft jaws for smaller diameters? I run loads of .5" dia parts on a 10" chuck. Bar loop stuff. Peet and re peet. Sub spindle too.
 
I do not understand the question. Is there a problem making soft jaws for smaller diameters? I run loads of .5" dia parts on a 10" chuck.
10" ain't 15". A 15" chuck is pretty cumbersome. Had this exact problem ... but instead of trying to hold a small chuck in the big one, I made a backing plate for the small chuck, adjust-tru type, with bolts threaded into the nuts in the 15" hydraulic chuck (4 1/2" thru-hole), that way the jaws weren't trying to crush the smaller chuck.

Still fonky because 2,000 rpm was all it got, but better than trying to hold dinky stuff with ten-pound topjaws.

Then I bought a little lathe, which worked much much better. If you do this very often, I can recommend it :D
 
I think a Warner & Swasey collet chuck that would fit a lathe chuck would be the berries because you would have a broad range of sizes.
Perhaps have some tool steel hardened to 46c or so and make it if such can not be found.

One to fit a 4jaw could be adjusted to near zero.
 
Thank you for the replies everyone. We decided to buy a smaller, 6" chuck to hold in the 15". That should allow us to clamp the range of different diameters we need to.
Cheers!

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Just make sure you are conscious of loosening the right chuck b/w parts, I have seen people loosen the large chuck when they meant to loosen the smaller one, and kaboom, chuck and damaged part on the floor.
 
I posted same question here a few months ago. Ended up with boring soft jaws to grip onto a straight ER32 shank. That means I can grab anything from 22mm and below. Cheap, fast and good solution.
 
Help me out here. What would the size of the order have to do with ease of holding small diameter work?
If I'd have jobs with large quantities or needed to use it every day I'd be willing to shell out money for a solution like collet chucks. As we stand now, we only need to hold small stock for small quantities and it doesn't happen often. A cheaper solution for us is better atm.

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