Are there any small manual chucks with two piece jaws, master jaws with top jaws? The closest I found was a Bison 4" chuck with one piece jaws but they offer soft master jaws. This is for the Emco lathe, it won't fit a larger chuck.
No matter what chuck you go for, if you can get a set of soft jaws for it, then take the opportunity to purchase them.
I have been using soft jaws for years, when soft jaws were nearly the price of a new chuck, and they are the cheapest and easiest way to get high precision turning on your lathe. In fact about 3 weeks ago, I turned up some 0.020", 0.040" and 0.060" thick by 2.5" diameter ali shims on my 5C version of soft jaws.
I have soft jaws for all my lathe chucks from 80mm right up to 6", in fact I won't buy a chuck unless I can easily get soft jaws for it.
The Taig 3 jaw has removable Jaws. They are aluminum. It is 3/4-16 mount, I have a MT3 arbor that is threaded 3/4-16 that I purchased from Little Machine Shop so I can mount the Taig chucks on my Mini Lathe, and with a MT5-3 adapter on my big lathe as well. They also sell a MT-2 to 3/4-16 adapter which works out good for my rotab and indexer. Good to get multi uses on all the different machines.
Hmm.. this is going onto a CNC machine and would need to be fairly stout with a speed rating of at least 4000RPM. The Bison while priced at 250-300USD seems like my only choice. i looked at other big name manufacturers, but turned up nothing. I also looked at the Bison 4" 5C chuck. I took a look at the Taig now, but it just doesn't look sturdy enough.
After a lot of searching any chuck manufacturer I could come up with I found TOS of the Czech Republic makes a 4" with two piece jaws. Now, I have to figure out how to get one.
That is an interesting problem, Nothing better than soft jaws bored to size for accuracy. Next best is an adjustabe chuck like the Buck Set-tru. one piece jaws all of them( 4"). The jaws are not as hefty as say a Burnerd in the 4" size but being able to accuratly center the work is the aim. On ebay those little Bucks are generally lightly used as they are very common on dividing heads. The Myford super 7 has one, much better than the 50 year old Burnerd that was on it.
I did also find Kalamazoo, Buck, and Pratt Burnerd make some 4" chucks, but no two piece jaws. I was really hoping to find a 4" manual chuck that used serrated jaws like used in CNC chucks. I only found one source, for a manual chuck like this, but 5" and larger.
The TOS is exactly what I want. I'm waiting on a reply. Not sure if I'd send my credit card info over there, however.
No reply from TOS. I did read online FWIW, that some Pratt Burnerd chucks are produced by TOS now. A little more searching yielded a company in Florida that listed some TOS chucks. I'm waiting on a reply to email, but will probably call them next week.