Nesting Collets

[Cannonmn]

CNC lathe takes 16c collets, but we don’t have let’s say 7/8” needed for aluminum shaft to be threaded. We do have 1.25” 16c collet and 7/8” 5c collet that is 1.25” od and slips right into the 16c, to be held by friction when hydraulic collet closer activates. The 7/8 aluminum rod would be inside the 5c for that collet’s full length. Already tried the multi-jaw chuck and it doesn’t work well on this shaft so installed the collet chuck. Haven’t tried this yet and there’s no emergency, if this is definitely a bad idea we won’t do it. Slippage between collets I doubt will occur, the collet closer exerts a huge squeeze, forgot the number.

 

[johnmontrose]

Hardinge makes a 16C to 5C adaptor:

https://shop.hardinge.com/medias/sys_master/images/h93/h8e/8802520006686/16C-to-5C%20Spindle%20Collet%20Adapter/16C-to-5C-Spindle-Collet-Adapter.pdf?attachment=true

Looks to be a bit specialised, only working with other things made by them.

Another one here made by Vicon, which looks more universal:

Vicon Precision Universal Collet 16C to 5C Adapter - 7249-16C

Offering a huge selection of industrial tool sales online. Find over 100,000 metalworking products, precision measuring tools, power tools & accessories.

www.penntoolco.com

 

[CarlBoyd]

CNC lathe takes 16c collets, but we don’t have let’s say 7/8” needed for aluminum shaft to be threaded. We do have 1.25” 16c collet and 7/8” 5c collet that is 1.25” od and slips right into the 16c, to be held by friction when hydraulic collet closer activates. The 7/8 aluminum rod would be inside the 5c for that collet’s full length. Already tried the multi-jaw chuck and it doesn’t work well on this shaft so installed the collet chuck. Haven’t tried this yet and there’s no emergency, if this is definitely a bad idea we won’t do it. Slippage between collets I doubt will occur, the collet closer exerts a huge squeeze, forgot the number.

Lyndex 16C 7/8" Round Collet | eBay

Used Lyndex 16C 7/8" Round Collet.

www.ebay.com

CarlBoyd

 

[Cannonmn]

Thx, $279. + s., I’d buy if I thought I’d need this exact work-hold even a few times a year but too much for a one-time need. If no one thinks doing this will somehow damage the lathe, I might try it.

 

[atex57]

A simple collared sleeve, 7/8 ID 1 1/4 OD sawed partly through in 3 places and through in 1. Spring it open a little. 5 minutes to make it.

Ed.

 

[L Vanice]

Thx, $279. + s., I’d buy if I thought I’d need this exact work-hold even a few times a year but too much for a one-time need. If no one thinks doing this will somehow damage the lathe, I might try it.

The 7/8" 16C collet on eBay in post #3 is only $49 with free shipping.

You should have a few 16C emergency collets on hand for this sort of situation. Used ones with holes smaller than your new need would be cheaper than $49.

But, if you have more time than cash, try the split bushing idea. I prefer to have a collar on the head of my split bushings in case there is heavy axial force on the work, like drilling.

Larry

 

[wesg]

Make a collar. Using a 5c in a 16c collet will likely only clamp at the rear of the taper. The front will be 'loose', likely not hold well, and possible damage the collet.

 

[Philabuster]

Make a collar. Using a 5c in a 16c collet will likely only clamp at the rear of the taper. The front will be 'loose', likely not hold well, and possible damage the collet.

X2. This is a bad idea. Make a split sleeve like others suggested instead to get you going.

 

[Dan from Oakland]

The Vicon adapters work pretty well in my experience. Contact Vicon directly, they are in San Jose, Ca.

 

[Toolmaker51]

The 7/8" 16C collet on eBay in post #3 is only $49 with free shipping.

You should have a few 16C emergency collets on hand for this sort of situation. Used ones with holes smaller than your new need would be cheaper than $49.

But, if you have more time than cash, try the split bushing idea. I prefer to have a collar on the head of my split bushings in case there is heavy axial force on the work, like drilling.

Larry

The collar offers resitance to getting pushed in, and visual reference of pulling out... Mine get a collar, entirely different reason.
Makes it impossible to mismatch the sides and potential axis. Cut carefully, even four separate 'petals' can be slid into a chucking arrangement.
I can't picture an instance choosing to close a collet in a collet. A collet developes grip to a surface via the taper, not the body. With minutes expent on a bushing HAS to be lower cost than replacing a sprung collet, a thrown part, or both.

 

[Bluejeep]

Mcmaster sells 16c collets. easy to have the correct one next day.

 

[rdenney]

I have a shop-made collet system that came with my lathe that uses sleeves to adapt the tapered collet to smaller sizes. It works well, providing a tight grip right to the opening.

Before cleanup:

After cleanup, holding a 1-1/4” bar (the tapered collet is 1-1/2”):

Rick “who will make sleeves as needed” Denney