3-jaw chucks: Who makes what?

[just old al]

Putting a new (to me) SB9 on line in my shop and decided to eeat myself to a new 6" 3-jaw chuck to replace the two battered monstrosities I have in the shop.

Looking at the vendor sites I'm familiar with shows me no names I'm familiar with and lots of choices. Also, all of them seem to have American pattern replaceable jaws - a feature I am unfamiliar with.

SO - bottom line (and yes I did search before asking) who makes a decent 3-jaw chuck for an SB9 that will simultaneously work with a decent TIR and not break my wallet?

Thanks - Al.

 

[strantor]

What's "decent" TIR?
I got this chuck, .003" TIR for $109
http://www.cdcotools.com/
P/N 25433

Need to buy a back plate that matches your spindle thread

 

[just old al]

"Decent" TIR: .003 sounds reasonable to me - not a problem.

 

[wildo]

I bought a Bison 3 jaw chuck that is self-centering with fine adjustment. It's pricey, but you can dial it in to be dead center. That was important to me. You can see it in my resto thread: http://www.hobby-machinist.com/threads/south-bend-9a-restoration-pic-heavy.44300/

 

[woodchucker]

I think 6" is to big for the SB9. I have a 4 jaw 6, that's fine, but for the 3 jaw, I have a 4" a 5 might work, but 6 I believe is too big, it will work, but I'm betting you'll hit your cross slide and not be able to get in close too many times.
Runnout will be based on how well you setup your backplate. So what you are looking for is a good chuck, and a good back plate... that you will machine. As long as it tightens down, does not deform, smoothly works. You want reversible jaws... do you need the option of soft jaws? If you have collets setting up the chuck is easier if the screws come in from the front. You can setup a rod with a center drilled out. Then mount it in the chuck, and use your tailstock to hold it centered on your machined backplate. then you can take transfer punches in the front and mark your holes. you can run an indicator on the rod next to the chuck to make sure it's dead on b4 marking, if not tap it into position. I don't believe its as easy to do a rear bolted chuck. Others might disagree and have come up with a way to do it.

 

[wildo]

I think 6" is to big for the SB9. I have a 4 jaw 6, that's fine, but for the 3 jaw, I have a 4" a 5 might work, but 6 I believe is too big, it will work, but I'm betting you'll hit your cross slide and not be able to get in close too many times.

I'm not sure how that would be possible. Even with the compound set parallel to the cross slide, the tool holder still sits to the side of the cross slide. But I suppose stranger things have happened.

 

[markba633csi]

I bought a 4" chinese 3J chuck for my 6" Atlas. 110 $ with backplate. Not too bad it's about .0033 runout. If you get a chuck with 2 sets of jaws, check them both right away- I had to return one set for a replacement; they were not made correctly. In my next life I'll spring for a Pratt Burnerd.
Mark S.

 

[just old al]

Re: Chuck info: Good data, all. Reason I was looking for a 6"er is that is what I have presently - two very, very shagged-out examples. TBH if I need things dead on I'll either use my 5C collet chuck or dial it up in the 4-jaw. Anything I do in the three-jaw is going to get an initial truing cut in any case, so a small amount of runout is not unacceptable.

This lathe came with yet another three-jaw - whose jaws had had pads welded to them...badly. That one went RIGHT into the tip once I took a good look at it. I ca handle runoput but that should have just run away.

As far as machining the backplate in situ - that's always been on my radar. Semi-finished backplates in 1-1/2 - 8 TPI are quite inexpensive - surprised me when I looked them up. i've done it from scratch with a raw casting before but that level of work, while entirely possible, just doesn't meet my time constraints anymore. Gonna throw my wallet at it this time.

 

[woodchucker]

I'm not sure how that would be possible. Even with the compound set parallel to the cross slide, the tool holder still sits to the side of the cross slide. But I suppose stranger things have happened.

You haven't opened the jaws, which is what would hit. but looking at your chuck, your jaws are definitely taller and may eliminate that inteference. But possibly reversing your jaws to grab something larger, I still think you have that risk. Maybe I'm wrong.

 

[intjonmiller]

I've been very pleased with my 6" 4-jaw scroll chuck from Shars on my 10" Logan. Should be pretty comparable experience to an SB9. I paid about $170 or $180, shipped (from their eBay store), for mine. IIRC it was about $10 more than the 3-jaw, which is about 5th or 6th down my list of future purchases, somewhere below a collet chuck and good set of collets. It is heavy and substantial and feels very well-made, and it came with a 1-1/2"-8 threaded backplate.