Identify This Chuck

Well that just sucks

The ''spiral assembly'' is called a scroll or scroll plate. You are proabaly going to need jaws to go with it also.

Somebody might have some ideas on fixing that one. I don't know how to do it.

Does it make any difference which scroll socket you use to loosen and tighten the chuck? I know on mine it makes quite a difference. Try it out...might keep it useable if you just have to use only one pinion/socket.

Randall Marx said:

Does it make any difference which scroll socket you use to loosen and tighten the chuck? I know on mine it makes quite a difference. Try it out...might keep it useable if you just have to use only one pinion/socket.

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I tried all of them and now it's completely random.

If I loosen then tighten several times it may vary anywhere from two or three up to about 10 if I try it's a 10 times I might be able to get below 2 it's totally random crazy

Yeah, what you have is a very worn chuck in regards to the area where the scroll plate rides on. These surfaces wear over time from use. Not much you can do for it other than buy a new chuck to replace it. I have heard of people going in and building up the worn areas and remachine to snug fit to the scroll. But is it really worth doing so? Ken

4gsr said:

Yeah, what you have is a very worn chuck in regards to the area where the scroll plate rides on. These surfaces wear over time from use. Not much you can do for it other than buy a new chuck to replace it. I have heard of people going in and building up the worn areas and remachine to snug fit to the scroll. But is it really worth doing so? Ken

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No it's not worth it. Now I gotta consider what I'm going to do about a 3 jaw Chuck or if I'm going to it all I have a couple of 4 jaw

Iced tea brands at I'm not familiar with like interstate and Phase 2 they sell a 6 inch 3 jaw Chuck for a couple hundred bucks I know these brands are Chinese so I have no doubt about that are they worth messing with it all?

It's a ***** to buy them used because you can't check them out unless it's Craigslist then I guess you can if there's a lathe set up

I have an old 6" 3-jaw that I got with my Atlas 12-inch lathe, both used very much before I got them. The chuck is a Phase II. After I fixed the backplate, I got it to less than .0005 TIR at the jaws and under .001 at 3" out from the jaws. I don't know if that is the normal for these chucks or not, but I'm very happy with it.

I have a 6" 3-jaw Chinese chuck with two-piece jaws I bought in 2000. First thing I had to do was dismantle it and clean out all of the grinding crud embedded into the chuck. Used a little moly-disulfide grease on the gear and scroll reassembled. Been using it since then. I have the back plate setup where the register is about .005" loose to the chuck so I can dial it in to run zero like a Adjuster-True chuck.

Okay well thank you all again maybe I'll try a phase 2. My health condition just turn for the worse so you won't see me for a little bit probably. It gets worse sometimes and I get it to sleep or try to

A scroll chuck is quicker to chuck up and it is easier to do repeat turning as opposed to a 4J independent. But many machinist just use a 4J and can dial down the TIR very quickly. Usually takes me 1-2 minutes on the 4J, but if you do a lot of repeat work it is a bit of a PTA. TIR is relative, if you are just turning and parting the piece off than it should not be a problem, but if you rechuck or do repeat work, then it is more important.

I like Ken's method of tweaking the TIR on the chuck, providing you have the repeatability and linearity in the scroll TIR. The TIR can change a bit over the clamping range of the scroll chuck. I am going to pull out one of my old Chinese chucks that came with my machine and use his suggestion to get the TIR down.

If you look at the specs for most chucks in the 6" range, even for high end chucks, it is usually a maximum TIR in the 0.003-0.004" range, generic Chinese chucks probably 0.006-0.008". Part of this is tweaking the back plate on your machine, and as Ken mentioned, you can work the TIR down a bit. As far as chucks, really a wide range in quality and pricing, buying used can be hit or miss unless you can check it first. If you need to get the repeatable TIR down to under 0.001" then you may consider a set-tru (adjustable TIR type) chuck. You might look at some of Shar's new line of chucks, which claim a 0.0012" or better TIR on their 6.3" and reasonably priced. I would not get the forged chuck, they are usually for higher RPM turning. They also have a set-tru type which is about 1/2 the price of a Bison or PDA.

KU 202-1791 CS63 6-1/4" 3 Jaw Cast Steel Self Centering Scroll Lathe Chuck TIR 0.0012
http://www.shars.com/products/toolh...-cast-steel-self-centering-scroll-lathe-chuck

SKU 202-5463 6" 3 Jaw .0005" Adjustable Universal Chuck 2 Piece Jaws TIR 0.0005
http://www.shars.com/products/toolh...-0005-adjustable-universal-chuck-2-piece-jaws