A Question about Turning or Modifying Toolholders

[Chewy]

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.

 

[homebrewed]

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.

 

[chatter chatter cut cut]

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.

 

[mickri]

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

 

[chatter chatter cut cut]

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.