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gunmakermike
03-23-2005, 10:27 AM
I found this old, flat belt drive unit at a reasonable price. It had years of accumulated grease that took a lot of scraping, solvents, and "Simple Green" detergent to clean up.

When I started test runs, I found some excentricity in the 3-jaw chuck. Hardly surprising on an old machine.

Does anyone have suggestions for fixing the chuck to get things straight & true? Seems like I saw an article on this a few years ago in HSM, but it seems to be hiding.

Would buying a new Bison chuck be the better way (to save time and frustration).

Can anyone suggest a reliable source of parts for old South Bend lathes?

SGW
03-23-2005, 10:30 AM
I assume the spindle itself is running true.

If it's just the chuck, you could try grinding the jaws, but presumably the scroll is worn as well and there isn't much you can do about that. Unless you want to spend the time messing with it for the sake of messing with it, I think I'd just buy a new Bison chuck.

garyphansen
03-23-2005, 10:52 AM
My sujestion is to take the three jaw chuck off and throw it away. (Or better yet, sell it on Ebay.) Replace it with a four jaw chuck. The spindle threads are most likely 1 1/2"x8 TPI unless you have the older 9 JR lathe. I have a Model A with a 4' bed, floor model. They are great lathes. The have solid cast iron bearings in the headstock and as long as you keep oil in the headstock they will run just about for ever.

Four jaw chucks are way more veristial and accurate than 3 jaw chucks. The only thing I use my three jaw chuck for is to stick the magnetic base of my intercators to. It has not been on the lathe for about 25 years.

There is a Yahoo web site that you can find a lot of info on your lathe.

Gary P. Hansen
ENGINEERING DRAFTING SERVICES

precisionworks
03-23-2005, 11:40 AM
Here are some sources I've used:

http://www.leblondusa.com/html/south_bend_history.html

http://www.dogpatch.com/bobp/sobel.htm

http://search.ebay.com/south-bend-lathe


This company has hundreds of chucks: http://smalltools.com/type-src.asp

You old chuck could make a nice stand for a Christmas tree......................

I use my 4-jaw & 3-jaw about equally. If the job's not really picky & the part is clean and round use the 3-jaw. The 4-jaw holds all the rest.

------------------
Barry Milton

[This message has been edited by precisionworks (edited 03-23-2005).]

WLW-19958
03-23-2005, 02:35 PM
Hi There,

How eccentric is your chuck? If it is really out, the jaws may be in the wrong slots in the chuck. Look and see if your jaws are numbered (1,2,3). And see if they are in the correct slots (sometimes, the number is in the slot under the jaws).

If they are in the correct order but in the wrong slots, you may have some eccentricity error. If they are in the wrong order, your chuck will be wildly eccentric.

Just though you might want to check this.

Good Luck!
-Blue Chips-
Webb

Stu Miller
03-23-2005, 03:10 PM
I'm with Gary. I almost never use the 3 jaw on my SB 9. I can achieve better centering accuracy in the 4 jaw by eye, and can get really precise with a dial indicator if necessary. The 3 jaw sits in the cabinet.

Stu Miller

JeffG
03-23-2005, 08:30 PM
I bought a South Bend 9A early this year. If you don't know your lathe's history, PULL THE SPINDLE and check the felts! This is not hard to do. My lathe had no felts - just a bit of old rag in the oil holes, and one of the bearings was badly scored. Fortunatly, with a good cleaning, new felts, the right oil, and careful adjustment of the bearing clearances, it seems to be running fine.

I've accumulated a fair amount of info on these lathes from this and other sources and would be happy to share if you email me off-list.

Jeff Greenblatt

gunmakermike
03-24-2005, 10:30 AM
<font face="Verdana, Arial" size="2">Originally posted by JeffG:
I bought a South Bend 9A early this year. If you don't know your lathe's history, PULL THE SPINDLE and check the felts! This is not hard to do. My lathe had no felts - just a bit of old rag in the oil holes, and one of the bearings was badly scored. Fortunatly, with a good cleaning, new felts, the right oil, and careful adjustment of the bearing clearances, it seems to be running fine.

I've accumulated a fair amount of info on these lathes from this and other sources and would be happy to share if you email me off-list.

Jeff Greenblatt</font>

gunmakermike
03-24-2005, 10:32 AM
Thanks to all of you! I'm new at this, and hoped for info from hands with experienc. Looks like I got it.

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gunmakermike
03-24-2005, 10:38 AM
<font face="Verdana, Arial" size="2">Originally posted by JeffG:
I bought a South Bend 9A early this year. If you don't know your lathe's history, PULL THE SPINDLE and check the felts! This is not hard to do. My lathe had no felts - just a bit of old rag in the oil holes, and one of the bearings was badly scored. Fortunatly, with a good cleaning, new felts, the right oil, and careful adjustment of the bearing clearances, it seems to be running fine.

I've accumulated a fair amount of info on these lathes from this and other sources and would be happy to share if you email me off-list.

Jeff Greenblatt</font>

Thanks for the offer, Jeff. I would really appreciate any info you could share.

gunmakermike
03-24-2005, 10:41 AM
<font face="Verdana, Arial" size="2">Originally posted by gunmakermike:
Thanks for the offer, Jeff. I would really appreciate any info you could share. How do you pull the spindle??
</font>

BillH
03-24-2005, 10:51 AM
I second the spindle pull, I pulled my spindle, and found the rear oiler was broken, replaced both. theres some scoring on my spindle bearings as well, but heck, still runs quiet and smooth.

topct
03-24-2005, 11:48 AM
Question, is the chuck a one piece or is it on a mounting plate?

My three jaw is off also, but after removing it from the plate and checking the runout of the mounting plate, it's like it was never trued to the spindle or it may have come off of another machine.

If it is a one piece you might take a look at the point that the chuck makes contact with the spindle. It could have a nick or burr on it at that point keeping it from screwing on all the way. That would throw it off.

Excuse my terminoligy here, someone knows what I'm talking about and can maybe clear up my explanation.

One other thing about the mounting plate, if it is that type, you might look for a match mark of some kind to make sure that at some time the two were seperated and remounted in a differant position?

------------------
Gene

[This message has been edited by topct (edited 03-24-2005).]

Carl
03-24-2005, 01:12 PM
How much run-out does it have? Most sources say that .003 is fairly common run-out for a 3 jaw. As long as the chuck will grip the work securely, the work will be accurately turned on the spindle centerline. The problem occurs when you can't perform all turning or boring operations on the piece without removing and rechucking it.

BillB
03-25-2005, 02:19 AM
Lots of parts are available on Ebay -- breaking up South Bends for parts seems to be a cottage industry. Just be sure you know what you're looking for/at and don't get carried away with the bidding.

A previous owner of my SBL 10K sold all the power feed parts (idiot!), and I replaced most of them through Ebay. Curiously, though, both my best and worst experiences were face-to-face transactions with actual machinery dealers.

Don't forget to tear down, clean, and rebuild the apron also. There are (or should be) wicks in there, too. There will also be lots of chips that have wandered in.

BillB

happy02
03-25-2005, 09:26 AM
I would take a very hard look at the chuck before I threw it away. It would be a shame to throw away a Buck and replace when it only needed TLC. If you remachine the back plate be sure to level the lathe first.
Does it have reversable jaws or 2 sets of jaws?