# A Question about Turning or Modifying Toolholders



## chatter chatter cut cut (Aug 21, 2022)

recently purchased an er32 collet set and collet holder all looks ok. however the 4 in shaft collet holders shaft is too large to fit inside the 3 jaw chuck and the headstock . is it possible to turn the shaft down to fit or is it too hard? i can return it but i think the shipping will equal or more than the original cost.thinking to turn it to a diameter that will fit and cut the shaft to about 2in.  all suggestions appreciated.


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## Ulma Doctor (Aug 21, 2022)

pictures may help here

often tool holders are softer than cutting tools.
it may be doable, but you may need to do the work between centers to keep concentricity


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## homebrewed (Aug 21, 2022)

I'm not sure why you want to use a collet holder like that.  Even if the holder and collets are perfect your TIR won't be any better than the chuck.

Most who use collets in their lathe either use ones that match the spindle taper + a drawbar, an adapter like this or something like this, which mounts on the spindle in place of the chuck.  These approaches will perform much better in terms of TIR.


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## WobblyHand (Aug 21, 2022)

For what it is worth, I bought the ER32 chuck for a 4" from LMS and mounted it on my mini-lathe.  I was and still am impressed with the very low TIR.  Under 0.0003" with 1/2" and 0.375" dowel pins.  The chuck taper itself measured 0.0001", it barely moved the DTI.


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## markba633csi (Aug 22, 2022)

Yes you really want a Morse taper collet chuck and drawbar for least runout
Better yet, one of those faceplate style collet chucks that would allow you to pass work all the way through (no drawbar)


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## Chewy (Aug 22, 2022)

I used a straight shaft in a 4 jaw chuck for years. I bought it to use ER32  collets that I had for the mill.  Had very low TIR, but work holding was very limited, a couple of inches. Best bet is to get  a spindle mounted colet chuck for longer work holding.  Morse taper might be better but will be limited in length.


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## homebrewed (Aug 22, 2022)

Chewy said:


> I used a straight shaft in a 4 jaw chuck for years. I bought it to use ER32  collets that I had for the mill.  Had very low TIR, but work holding was very limited, a couple of inches. Best bet is to get  a spindle mounted colet chuck for longer work holding.  Morse taper might be better but will be limited in length.


I have a set of Morse-taper collets I bought years ago.  I don't use them much because they aren't pass-through.


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## chatter chatter cut cut (Aug 22, 2022)

I really appreciate all the responses, thank you. this hobby lathe has no morse taper.and id of about .875 ,the collet holder shaft is hollow. id .657 od .995 . my plan is to chuck the collet shaft between centers and to turn to a diameter to fit in the chuck. and then shorten the shaft so that the collet does not stick out more than is necessary.and possibly bore the id to pass 3/4 in bar.however all is presently on hold till the back problem is resolved.


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## JimDawson (Aug 22, 2022)

chatter chatter cut cut said:


> recently purchased an er32 collet set and collet holder all looks ok. however the 4 in shaft collet holders shaft is too large to fit inside the 3 jaw chuck and the headstock . is it possible to turn the shaft down to fit or is it too hard? i can return it but i think the shipping will equal or more than the original cost.thinking to turn it to a diameter that will fit and cut the shaft to about 2in.  all suggestions appreciated.



Try a file test to test the hardness.  Mine are pretty hard.  I did cut mine down to 3'' but I used an abrasive cutoff wheel.


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## brino (Aug 22, 2022)

@chatter chatter cut cut ,

Does your lathe have a threaded spindle?

If so maybe one of these would fit:
https://bealltool.com/products/turning/colletchuck.php

I previous wrote about them here:
https://www.hobby-machinist.com/threads/is-there-a-definitive-article-on-collets.36227/post-308310
and here:
https://www.hobby-machinist.com/threads/is-there-a-definitive-article-on-collets.36227/post-308552

As you can see in the second post above, on my SouthBend 9" this system allows me to put stock thru the spindle, right up to the spindle ID of 3/4".

Brian


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## Chewy (Aug 23, 2022)

chatter chatter cut cut said:


> I really appreciate all the responses, thank you. this hobby lathe has no morse taper.and id of about .875 ,the collet holder shaft is hollow. id .657 od .995 . my plan is to chuck the collet shaft between centers and to turn to a diameter to fit in the chuck. and then shorten the shaft so that the collet does not stick out more than is necessary.and possibly bore the id to pass 3/4 in bar.however all is presently on hold till the back problem is resolved.


 Something don't add up here.  If you turn the OD of the collet chuck down to .875 with an ID of.657 that leaves you with .218 divided by 2 = .109 wall thickness. That should work. If you bore out the inside to .75, that will leave you with a wall thickness of .0625 which is pretty thin for something subjected to side loading stress. I thick you will end up with a bad TIR.  Just my thoughts.


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## homebrewed (Aug 23, 2022)

The through hole diameter of my 3-jaw is .63".  Aside from the concern indicated by @Chewy, you need to examine your 3-jaw to determine what the diameter of its through hole is before boring out your collet holder.  If it's comparable to mine you won't gain much.


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## chatter chatter cut cut (Aug 25, 2022)

I went for it . the shaft was hardened however the braised carbide tool cut good and left a very smooth finish . a real birdsnest of redhot steel wool.. after many passes the shaft was reduced to the usable diameter.then cut off to about 2 in using a side grinder and cutoff wheel . it will chuck up and allow a pass through altho not a full 3/4 in. not happy about the amount of runout . not sure where the error is yet.


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## mickri (Aug 25, 2022)

If you don't want to buy the Beal collet chucks you can make one.  That's what I did.  You do have to be able to cut a 1.50mm thread.  I modified my craftsman 12x36 so I could cut the common metric threads.  By making your collet chuck runout is a non issue.  









						No excuse not to make an er32 chuck for the lathe
					

I am just about finished with the tool holders for my norman style qctp and already realize that I am going to need more tool holders.  Can you ever have too many??  I see an add on Craigslist for a company selling some 1018 crs 1 1/4" x 2" flat bar.  Stop by and it is a CNC machine shop trying...




					www.hobby-machinist.com


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## chatter chatter cut cut (Sep 3, 2022)

update  turned the shaft of the collet holder to a diameter that fits the three jaw chuck and cut to about 2 in. long. it is hardened. however a sharp braised carbide and multiple passes producing huge birds nest of red hot steel wool produced the desired result. run out is not good after careful checking the taper in the holder is not good. every other check is ok at .003  checked chuck and shaft of holder and body all are good.


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