4 jaw lathe chuck recommendations?

I'd like to get a 4 jaw lathe chuck for my south bend 13" O series tool room lathe.

I need some help figuring out:
1) What chuck will work?
2) How to get a back plate that will fit my lathe?
3) What size chuck should I get 4"? 6"? 8"? Larger?
4) Is there anything I should watch out for buying a 4 jaw? Things like auto-centering or other fancy add-ons that I should definitely get?

How do I know what back plate to get? Are all "south bend lathe chucks" made to fit all south bend lathes ? Do they even make back plates? Or is it an unspoken rule of the machinist trade that you make your own to fit your lathe (right of passage)?

Would any of these chucks work?
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=south+bend+4+jaw+chuck&_sacat=0

Specifically this chuck: http://www.ebay.com/itm/SOUTH-BEND-...169809?hash=item440c6bd5d1:g:MDEAAOSwVgZZsGhw

And this one?
http://www.ebay.com/itm/SHARS-6-4-J...232600?hash=item51b98acdd8:g:HgUAAOxy0bRTAk~o

This one says "self centering 4 jaw chuck" is that of any use? Or does it work like a 3 jaw where they all go in at the same rate and can't be adjusted independently?
http://www.ebay.com/itm/8-4-Jaw-Sel...d=322803760239&_trksid=p2047675.c100005.m1851

 

Your thread mount size on your lathe is the first thing you need to know. Note that the self centering example you showed doesn't have individual adjusters, so it would indeed be like a 3-jaw and would defeat your purpose. The concentric grooves in the face of an independant 4-jaw are very helpful for getting in the ball park. Sometimes I setup right on the bench and then mount to the lathe and then dial it in.
Some chucks have the thread mount incorporated right into the chuck so there is no separate backing plate. My 4-jaw is like that. Others have more knowledge about brands etc, but buying used can be a crapshoot. And those things get awfully pricey!

Pete

 

You can get a four jaw scroll chuck where the jaws move together in sync, they are for machining square cross section objects as well as round. Then there is the fancy "System Westcott" four jaw chucks that combine a scroll chuck mechanism with four independently adjustable jaws: they would be great for machining a batch of irregular castings. You'd set it up initially for the first object and then easily chuck up any similar one. I have a Rohm 10 inch version of one of these which I have to machine an adapter for. Finally you have the common four jaw chucks, these are mechanically simple and so long as the jaws aren't a sloppy fit and the adjuster screws turn freely they are hard to muck up as they don't rely on accurate machining to work.

Most chuck retailers find it's easier to stock a series of premachined adapters to match the lathe to the chuck, you lose an extra inch or so between jaws and tailstock but you can adapt it to any new lathes you buy. I have a Chinese 10 inch four jaw that didn't even come with a badge: there's a machined circle on the front for a retailer to glue in a badge and rebrand it to whatever name they want. That said, it compares favourably to name brand chucks I own, jaws are a tight fit and the various faces I measured with a dial indicator after mounting showed it was true to 2/10th of a thou. I bought the chuck online for $150 and the steel D1-5 adapter for $40. The chuck manufacturer should list the rated RPM their chuck can handle which can be an issue for faster spinning lathes.

 

David - why would the Shar chuck make a machinist cringe? Seems well made and made of hardened steel instead of cast iron like south bend stuff.

Petee - I think the thread I need for the 13" O series tool room lathe I have for a 4 jaw chuck is 2 1/4" - 8 thread.

On page 52 in this manual it says the 4 jaw chuck part number is CL4207LQ.

http://neme-s.org/Shaper Books/South Bend/SB Catalog_Laathe_Mill_Shaper.pdf

I get why a 2nd hand 3 jaw chuck would be a crap shoot to buy, but does that apply to a 2nd hand 4 jaw chuck? If each jaw is independently adjustable any wear and tear/slop in the threads should be easily adjusted out?

Would the original south bend 4 jaw chuck (CL420LQ) be a good buy? I wouldn't mind keeping original south bend parts on the lathe.

http://www.ebay.com/itm/SOUTH-BEND-...169809?hash=item440c6bd5d1:g:MDEAAOSwVgZZsGhw

Or is the Shar chuck in 8" version better that the south bend chuck I posted above?

 

This is what the seller of the south bend chuck said:

Do you thing the chuck is worth it as stated for a total shipped price of $300?

The Shar chuck seems like an ok alternative but there are no auctions where the chuck has been bundled with a back plate that will match my lathe in the 8" size. I might have to message them and request an auction be put up for me to buy if they have it in stock.

So it seems it comes down to: Old south bend chuck or new cheap Shar chuck? Which will be the better long term purchase? Votes please!

 

That SB will outlast all of us. Thanks for linking the catalog. That's awesome. I see that Skinner 4207 weighs 40lbs! I'd buy it. Also the seller appears to sell more than he buys and has 100% feedback. Looks like a winner if you have the dough.

Pete

 

Knowing that I have been looking for a similar chuck for my lathe up until one fell in my lap.. That Skinner chuck on Ebay is worth the price.

 

Sounds good guys I'll see about buying it tonight. I wonder if he has the chuck key to go with it.

I'm slightly worried I might have misjudged the thread type on my machine. I think it should be 2 1/4" - 8 but I'm not a hundred percent sure since I don't have pictures showing the chuck number I currently have or the thread size on the spindle. According to the book linked above it should be what my machine takes but it would be nice to be sure before dropping 300 bucks.

 

zap,

Worst case you have to make a new backing plate..... (or buy one they can be had new for $65-$85 for "Standard" sizes. these will need fine tuned to fit your chuck). This is what I have to do for my Heavy 10 SB it has a 1 7/8"x8 spindle. Noone has these anymore. I just have to order a section of cast Iron (or if you're one of the Iron mongers on these boards cast one) Drill and thread the spindle thread (this can be done in a 3 jaw). Then thread the plate onto the spindle. Cut the OD and register. (in theory this backing plate is tuned to your machine as it was turned on your spindle). then drill the mounting bolt holes and you're good to go!
Use the ill fitting backing plate as the pattern (measure the width and depth of the registration shoulder, bolt pattern etc.) when you finish the proper fitting one sell the old one of ebay to cover the cost of the new one!
The Chuck here is the important part, and the most costly. backing plates are easy and relatively cheap.

CBB

 

Another thing to consider on cheap 4 jaws, is how square the inner face of the jaw is to the face of the chuck.

I have an el'cheapo 4 jaw (busybeetool.com) and the jaws will not grip anything squarely. Sure I can still adjust stock to get concentricity (sp?) but it pinches rather than grip.

I currently use a garbage 3jaw to hold a bison 4 jaw in my big Monarch. I don't have a mounting plate for the 4 jaw (camlock), so I've been using the lathe this way since I got it into the shop.

 

Alright I pulled the trigger and bought the chuck. Managed to lower the price a bit by choosing snail mail which is helpful.

Now, how do I know what chuck key size to buy for it? I assume it won't come with the key.

 

Have you tried grinding the jaws in situ on the lathe?, there's a preloading plate you can make with the four jaw to allow the screws to be tensioned in the correct direction when trueing the jaw faces.

https://books.google.com.au/books?i...#v=onepage&q=lathe chuck jaw grinding&f=false

 

I actually early on, and didn't get the best results. No doubt because I miss stepped somewhere in the process. The chuck in question gets used in a rotory table for the mill now so I'm not so concerned about things slipping while it spins a 1000rpm.

I just wanted to add that there's pitfalls to buying cheap that may not be so apparent as the nasty chinesinum smell. I would hazard a guess that those paying small money for a chuck won't have the sort of rig required for truing up jaws.

 

It's not too onerous to do, my Bison 8 inch three jaw was bell mouthed after a nasty crash and I was able to true it up nicely by mounting a small plunge router on the tool post to spin a small ruby grinding stone. There was no need for a hard to get tool post grinder attachment. At any rate there would be nothing to lose by trying the method.

 

Sry if I gave the impression that it was too difficult a task and / or required something extra ordinary in tooling to attempt. I just happened not have the best of luck with the process.

Something else to consider is the reasoning behind why the chinesinum chucks need truing in the first place. The jaws don't sit snuggly within the chuck's slots. So, if you tighten inward they settle differently then they do if you're expanding to hold the ID. You don't necessarily always want to flip the jaws.

It's not a case of a damaged jaw and/or wear. It's simply a bad design.

 

There are some quality chuck manufacturers in China, my particular no-name 10 inch 4 jaw had some markings on the box that ID'd it to a company that had made lathe chucks since the 1940's. It was cheap and I can't fault it in any way, apart from the sharp edges around the jaw grooves which you could argue would allow dirt in if lightly bevelled. There is a huge variation in quality and no real way of telling short of taking a gamble and buying one. I guess I got lucky with my one and wouldn't hesitate to get a D1-3 10" if I could find one of that brand again.

Chinese electronics have been very hit and miss on the other hand with lots of fake components and batteries, but that's another topic altogether.

 

From a quick Google search it looks like the Skinner uses a 5/16" chuck key. Might want to double check it on delivery. MSC has them for about $25 https://www.mscdirect.com/browse/tn...s?searchterm=lathe+chuck+key&navid=4287921328

Or you can find them on Amazon for about $7 -$10