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View Full Version : Compound Screw/Nut for SB 9"



garagemark
02-22-2011, 05:24 PM
The compound screw/nut on my SB 9" is so sloppy that I literally cannot use it at all. I have the compound cranked tight against the stops so it won't shimmy back and forth, so I can essentially only use the cross slide for any operation. Not good.

Anyway, I obviously need to obtain a new screw and nut for the compound (large dial). I have cruised evil-bay, and there are a couple of shop made screws available from the same guy. However, I know nothing about the seller, so I have no idea whether this would be a quality item or not.

http://cgi.ebay.com/SOUTH-BEND-LATHE-SOUTHBEND-COMPOUND-SCREW-9-10K-LARGE-/300529203342?pt=LH_DefaultDomain_0&hash=item45f8efb88e#ht_500wt_1156

Anyone know of of this guy, or a reputable place or contact where I can get a good quality shop made screw and nut... hopefully without breaking the bank?

Mark

JCHannum
02-22-2011, 06:31 PM
I can't speak for the linked seller other than to say the price is not bad and the quality does not look bad. He also has nuts available. He does have a good feedback.

The only other place I know of who sell these parts is Miller Machine and it appears they are having some problems due to illness. You can contact them to see what they might have available from stock.

http://www.millermachineandfabrication.com/default.htm

You can try Mermac for used parts. Dave is a good guy, and won't sell worn out parts.

http://www.mermac.com/

RussZHC
02-22-2011, 06:42 PM
I bought an iron nut and section of Acme rod for my replacement project on my Sheldon from Tom. [Sheldon old enough to be square thread].
Granted I have not yet assembled the parts on the lathe (unheated shop, way too cold) but they do fit together well and the finish is quite good.
My comment to him was this was the way the pieces from Sheldon should have been made in the first place (the original cast iron nut seems very porous and definitely contributed to accelerated wear IMO).
Double check but I think he makes his wares (nuts, screws etc. for SB, Logan and a bit for Sheldons) to a higher class of fit than some.

When I last communicated with him in late Dec/early Jan he was in process of adding more to his line (he has had all of the SB sizes as far as I know but there was one odd one for another manufacturer that he did not have the tap for in the higher class of thread...forgotten if he just taps or uses a mix of single point and taps as best suits).
Delivery was quick (Canada) and smartly packed (heavy, heavy wall cardboard tube rather than a USPS box).
Definitely recommend.

Dr Stan
02-22-2011, 07:18 PM
May want to give this guy a shout:

Matt Krug 815-434-5897
http://www.lostcreekmachine.com

I just bought a cross slide nut from him for much less (40%) than what SB wanted or what it would have cost me for the tap. Fast service and good quality. They advertise in the HSM magazine, but so far not on the forum.

Stan

justanengineer
02-22-2011, 10:13 PM
If your lathe works, even somewhat, why not simply turn a new screw and nut for it from mild steel and brass? Machine tools can fix themselves just as easily as others can if you consider the possibility. I think you would be just as surprised by what folks do with machines that are worn out as I am of what some on this board do with the imported ones.

Arcane
02-22-2011, 11:07 PM
If your lathe works, even somewhat, why not simply turn a new screw and nut for it from mild steel and brass? Machine tools can fix themselves just as easily as others can if you consider the possibility. I think you would be just as surprised by what folks do with machines that are worn out as I am of what some on this board do with the imported ones.
I was wondering when someone would state the obvious! :D

Dr Stan
02-23-2011, 12:09 AM
If your lathe works, even somewhat, why not simply turn a new screw and nut for it from mild steel and brass?

Good idea, just the wrong materials. 4130 stress proof or similar for the screw and bronze for the nut.

garagemark
02-23-2011, 08:10 AM
I had thought about doing it myself, but I am not very proficient at using the lathe to begin with, and know nothing about cutting acme threads (and very little yet about cutting ANY threads). I am still quite amateurish with metal working tools to this point. My thoughts are to tighten this old machine up as best I can, then I can learn the finer points of turning.

Mark

Dr Stan
02-23-2011, 11:15 AM
One technique is to run silver solder into the internal threads just enough to build them up and then run a tap through to bring it back to specs.

atty
02-23-2011, 12:44 PM
I bought a cross slide nut from your Ebay seller that you're referring to, and I certainly have no complaints. I had to do some minor machining for mounting, but that was expected.

His quality is good, and one definitely cannot complain about the price. I looked at it as a quick way to get a functional fix in place, even if I had to redo it later, hence I did not replace the screw. My problem was nowhere near as bad as yours....about .060 slop in the dial. More of an irritation than anything else. The nut replacement alone dropped it to .017, thus placing the screw issue on the "I'll get to it later" list.

justanengineer
02-23-2011, 01:32 PM
Thanks for the correction Dr Stan. Not sure what I was thinking, but I know what I was drinking after a long day. :)

Personally I think this is a great project to learn lathe operations on. Its relatively straightforward to do, teaches basic threading/turning, and uses only the most common tools/gages which you will probably need later anyway. Look at it this way, you could save yourself money, time (few hours in the shop vs few days waiting for the brown truck), and might even pick up a small source of income creating these for others. Plus, you know youre not a scam, when to expect delivery, and that in the end it will fit the way you want without a lot of play between screw and nut.

If youre lacking knowledge, ask your questions on here and get a good thick college (professional) textbook. Yard sales/flea markets and Amazon are a great source of these for a dolar and will teach you more than any $19.95 bookstore special.

garagemark
02-24-2011, 09:17 AM
OK, I'm looking at doing it myself. I expect an Uh-Oh or two, but what the hell; that's how you learn.

I have the machinist handbooks, but have not looked at them hard yet.

If I do this, I'll certainly be in touch with you guys again. If I decide against it, I'll just slowly let this thread die! :rolleyes: