[ptxman]

I have a Bison 5C collet chuck with an integral D1-4 backplate mount that I use it on my lathe. I was thinking it would beneficial for me to also mount this on my 8” rotary table. That way I can accurately hold anything with the collets for radial/indexing operations on the mill. Better yet if I could maintain the workpiece in the chuck & move it back & forth from the RT to lathe for certain operations. I haven’t come across any commercial fixtures like this, any bacplate accessories seem to be the same diameter as the chuck & notreally mountable like with a flange. I considered:

- machining a dedicated ‘disc’ with holes that mate chuck’s D1-4 pins extending off the back & with integral mounting holes on an extending flange to clamp the chuck/plate assembly to the RT tee-slots (seems like somewhat of a project, at least for my skills).

- removing the pins from the back of the chuck (they appear to be held in position with allen head cap screws, kind of indexed into the pin side) which exposes what I suspect is a pretty accurate rear face of the chuck, then mounting this to the RT with some simple type bar clamps once centered. (I’m doing this now with a conventional 3-jaw chuck, but it is already a plain back style so no pins to contend with). But is removing/replacing the pins advisable in terms of maintaining chuck accuracy?

If these options aren’t advisable for any reason, am I looking at buying a plain-back 5C collet chuck just for the use on the RT? I’ve seen less expensive 5C collet holder ‘blocks’ with variations of a lever activated clamping mechanism. They cost less than a 5C chuck & could be similarly mounted, although most appear to ground square & intended for mill vice setups etc. Any help/comments appreciated.

[DIY-Guy]

Hi,
Are you talking about remounting a tool back into the chuck in the same position without having to measure or realign the depth again?

I haven't done lathe work yet, so I don't know if this could be helped by the quick change types of tool holders. I've seen interesting devices after searching "quick change toolholders" and "automatic tool changers." Good luck!

DIY-Guy "Slowly ramping up to CNC thinking."

[ptxman]

Not so much the depth, but the centering relative to the RT center. Ive since looked into this a bit more & I think if I just modify a D1-4 backplate to align & be clamped on the RT, its pins will accept the chuck just like on the lathe & all will be well.

[Cyclotronguy]

Hi there,

My lathe uses D1-6 chucks and such. I've a 6-1/2"Yuasa spacer that has an adjust true 3 jaw chuck that bolts on from the front. Removing the chuck it appears that in theory at least taking 2" thick stock and replicating the adjust-true pocket on one side and a D1-6 on the other is fairly straight forward exercise.

Of course one has to provide locking for the pins on the chucks. OEM for lathe spindles is 1/4 turn cams that engage the pins. I was thinking that stripper bolts could be reground such that the shanks were tapered, and that those tapers would lock slightly modified pins in place.

Cyclotronguy

[Dr. Olethro]

Hello there,

I believe there is an exact solution to your problem. Emco-Maier has an adaptor which bolts directly onto a milling machine table or other flat surface and will accept any D1-4 chuck and lock it in place, as if it were a D1-4 spindle. I bought one several years ago from Blue Ridge Machinery, but I do not know if they still stock the adaptor. It was a bit pricey, but it allowed moving the chuck directly from my lathe onto my milling machine, without loosing even a thousanth. Well worth the money, in my opinnion. I also have two Bison collet chucks, one plain-back and one with the D1-4 mount. Buying the first one would ordinarily have been enough, but the closeout price of the second one was just too low to resist.

Hope this helps. Dr. Olethro