# South bend 9 cross slide



## Oildrips (Mar 8, 2020)

Hi there. Have a new to me South Bend 9 that seems to have some play in the cross slide. I can turn the handle a fair bit before the screw bites into it. I have seen on eBay that a new brass feed nut is available (trying to order one), but in looking at the parts diagram led me to a few questions:

1. what does the pin in the neck do?
2. are replacement pins available
3. What does the set/lock screw in the top of the nut actually lock?
4. Is it normal for there to be a bit of play in the cross feed?


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## Ulma Doctor (Mar 8, 2020)

i'm not sure what the pin does 

unless you have a brand new machine, there will be play in the leadscrew.

the brass nut will be the first thing to wear, then the screw is next.

you may be able to change the nut, but the screw may also have wear- just be aware.

i made nuts from delrin and eartalyte . i was able to make the clearances tight, even on a worn screw.
the delrin nut worked especially good


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## Janderso (Mar 8, 2020)

Mike, do you think the delrin would make a better, more durable nut?


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## SLK001 (Mar 8, 2020)

You most likely will have to replace the cross slide screw also.

Not sure what the pins are for (maybe has something to do with a taper attachment).

The top thread is where the nut is screwed into the cross slide.

Sometimes the play on an older machine is just too great to be able to do good work.  My cross slide had 0.060" of slop in it when I got it, which made it near impossible to thread.


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## Oildrips (Mar 8, 2020)

Could the pin be a lock pin? Tighten down the screw on top and it pushes the pin against the bore of the slide? I’d assume there would be a bit of rotation of the nut as you turned down the lock screw that could take up slack


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## DavidR8 (Mar 8, 2020)

@Oildrips do you have a photo of the pin? 
I have the SB 9 rebuild manual which may have some info. 


Sent from my iPhone using Tapatalk


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## Surprman (Mar 8, 2020)

The rebuild manual indicates the pin is used to vertically center the nut.  (There is a procedure involved so that the nut doesn’t bind in operation.).  The top thread is for the cross-slide bolt (that bolt comes out to disengage the cross-slide leadscrew when you are using the taper attachement to move the cross-slide).   I would guess that without the pin, the bronze nut would shift around more when the cross-slide nut is removed.

Rick


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## Oildrips (Mar 8, 2020)

DavidR8 said:


> @Oildrips do you have a photo of the pin?
> I have the SB 9 rebuild manual which may have some info.
> 
> 
> Sent from my iPhone using Tapatalk


The pin goes in the side hole. Doesn’t look like it comes out. It’s flush with the body.


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## Ulma Doctor (Mar 8, 2020)

Janderso said:


> Mike, do you think the delrin would make a better, more durable nut?


for longevity, yes. delrin will wear the shaft less than brass or bronze will
a bronze or brass nut will transmit force better and deform less during heavy cutting forces.
but in a small lathe the forces are not as great, so the playing field may be equal


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## graham-xrf (Mar 9, 2020)

It will be a bit down the fix-it-up road for me, but I am also thinking to do this (use plastic for something better than bags). So..

Is Delrin maybe another trade name for what I know as nylon?

I have come across a few more materials.
Turcite, Rulon, Moglice, and I dare say there may be many more.
The game seems to be to mix various harder wearing particles into polymer plastics e.g bronze powder into PTFE.
Some of these in sheet form are used to stick to machine ways. (Burn your bridges and grind them down first)!

Some plastics are tough in hanging on to their own substance, but are maybe too "flexible", Try to file some nylon and see.

Then we have the cross-linked hard stuff. All kinds of epoxy. What happens if one machines a nut out of carbon fibre composite? Maybe experiment, and mix some bronze powder, or any other stuff that one thinks might have a better future than wear-out-able brass, with some JB-Weld Marine, and make a nut?
Hmm - maybe the JB-Weld by itself might do.

Seriously though, Delrin sounds like it might be the easiest, most logical "upgrade". Very easy to get, and you can go for something else if it gives you problems.


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## DavidR8 (Mar 9, 2020)

Here’s a couple of pics from the manual regarding backlash. 












Sent from my iPhone using Tapatalk


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## Ulma Doctor (Mar 10, 2020)

graham-xrf said:


> Is Delrin maybe another trade name for what I know as nylon?
> Seriously though, Delrin sounds like it might be the easiest, most logical "upgrade". Very easy to get, and you can go for something else if it gives you problems.


Delrin is a brand name for the POM , the DuPont Corporation produces


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## frankly2 (Mar 10, 2020)

The “pin” is there for the lathe not equipped with the taper attachment. See attached pic......


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## finsruskw (May 23, 2020)

Curious as to where you found that parts page?


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## frankly2 (May 23, 2020)

finsruskw said:


> Curious as to where you found that parts page?


It came with the lathe when I bought it. It was published and provided by SouthBend. The original owner kept all the manuals and catalogs with the lathe. He gave the entire collection and the lathes he purchased to his son, I bought all from him some years back. So I’m the second owner.


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## finsruskw (May 23, 2020)

frankly2 said:


> It came with the lathe when I bought it. It was published and provided by SouthBend. The original owner kept all the manuals and catalogs with the lathe. He gave the entire collection and the lathes he purchased to his son, I bought all from him some years back. So I’m the second owner.



Thank you!
Are these available anywhere for down load so one may put together the pages they need?
Some of the tractor foums I frequent have a section for this type of  info available to members.


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## frankly2 (May 23, 2020)

finsruskw said:


> Thank you!
> Are these available anywhere for down load so one may put together the pages they need?
> Some of the tractor foums I frequent have a section for this type of  info available to members.


I haven’t thought about it but I suppose a person could scan the pages to pdf and Put them on the web, but I’m not sure how and if that might be violation of copyrights. Helping someone with an excerpt of one page is one thing but publishing the whole manual would be another ! Then again, handing a copy from one person to another ?


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## finsruskw (May 23, 2020)

I would imagine that would have already been done if only I knew where to look!


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## frankly2 (May 23, 2020)

finsruskw said:


> I would imagine that would have already been done if only I knew where to look!


Grizzly Industrial now owns the SotheBend rights to manufacture, they may know where to get or have those parts manuals. I found thru them the serial card for the manufacturing of the 9” I own. They probably can get the info you need, give them a try and see !
This is what I requested from Grizzly and received from their Archives..........


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## mcload (Jan 19, 2021)

Hello all. I thought I would chime in on this subject as I own 2 South Bend 9" lathes and I am familiar with this part.
First, the pin (shoe) on the side of the cross slide (CS) nut does indeed "lock" the nut to the side of the mounting hole. And
by "lock" I mean it applies pressure to the nut to take up any play or movement that would show up as increased backlash.

This shoe is forced out laterally by the top screw, a very small 5/16-24 screw with a 45-degree angle on the bottom. Screwing
down on it forces it to push the shoe outward (the shoe itself has a 45-degree angle. (I will attempt to provide a photo). 
These pins are very small and difficult to come by, tho they may show up occasionally on Ebay. A problem that develops is that after
decades of swarf and zero lubrication, the threads on this screw as well as the shoe itself can become quite stuck, resulting in a buggered 
up screw slot. So much so that it may be impossible to remove. (I do wish that SB had used an Allen head instead of a straight slot).
I HIGHLY recommend that you replace your cross-slide nuts immediately if you have not done so yet, both on the cross-slide and on the upper compound rest. Backlash will be reduced to a very great extent. But the absolute minimum amount of backlash will only be achieved by replacing both the nuts AND the ACME thread. (a word about that below).

In regards to a nut made of Delrin, I think that yes that is possible, but being plastic, you will not get as much "mileage" out of it as opposed to brass or bronze. I love the machinability of Delrin, but in this case, I don't think the wear factor is a good one. The brass replacement nuts aren't very expensive, so there's really no reason to machine one out of Delrin. If they were a good option, Ebay would be full of them for people to use.

There is a lot more info you need to know about these cross-slide nuts. To help make this post a lot shorter, allow me to recommend a thread I started over on Practical Machinist entitled "9" Cross Feed Nut Replacement". (I cannot post a link here apparently)

There is also something that you can help me with. I have discovered that there is NO hole at the bottom of the vertical shaft that goes into the internal ACME threads on the nut, either on the original nuts made and fitted by S Bend, nor on the new reproductions. Without a small hole, the screw threads get absolutely NO lubrication causing significant premature wear to the mating threads! The way it SHOULD work is that during the course of regular lubrication of your machine, you should unscrew the slotted screw; fill the cavity with oil; work the handle crank to spread and distribute the oil over the entire CS thread (may take more oil as you do this); then re-install the top screw, Be careful not to bear down to the point of buggering the slot!

Where you can help: If you own a SB 9" or 10" lathe (light), and if you have the original nuts in there, I need to know if you have an oil hole that extends into the threads or not. Assuming you can back off the screw, you can test this either by filling the column with oil to see if it drains, or, by inserting a small wire to feel if there is a hole present. I have two original SB nuts and neither of them are drilled! I would like to know if there are more out there like this! This info would be very helpful!! 

One last parting word of advice. To the best of my knowledge, there is no way to adequately oil the CS screw without removing the top compound rest assembly...what a pain! The only other way is shooting oil up from the bottom, through the bed "webs" up into a small hole in the casting! It's not supposed to be this hard guys!!  So, if/when you do replace the cross-slide nut, be absolutely sure you drill a small 1/8th" hole that extends down into the threads...the repros are not drilled. This is save your CS mechanism from future pre-mature wear.
Again, please thoroughly read the thread at the link above for some tips. (When replacing the nut with a repro, be certain to deburr the hole for the shoe...it must slide freely!)
	

		
			
		

		
	





Regards,
PMc


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## finsruskw (Jan 19, 2021)

I bought that manual (copy) from Grizzly and found it to be somewhat vague in some aspects.

The nut that was on my 9A was not drilled and there was nothing in the threaded hole, except petrified swarf
The replacement nut was not drilled either.

I installed the replacement and it did lessen the backlash somewhat but not as much as I was hoping for.


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## mcload (Jan 19, 2021)

Thank you for the info about the lack of hole.

By the way, I may have found a suitable replacement for the slotted screw on this nut.
It is at McMaster Carr; 10 bucks for a pack of ten. It is item number 92785A554.
These are ½" long; have a conical end; hex head; and stainless steel. (3/8" length is
available if you prefer). The conical end should do the trick, tho I have not yet tried.


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## finsruskw (Jan 19, 2021)

mcload said:


> Thank you for the info about the lack of hole.
> 
> By the way, I may have found a suitable replacement for the slotted screw on this nut.
> It is at McMaster Carr; 10 bucks for a pack of ten. It is item number 92785A554.
> ...


Is the part number for the pin PT358NK1??

I am familiar with the conical end set screws as they are also used as bearing retainers on Cub Cadet mechanical PTO's
And, since my last post, I have finally figured out just what the deal is with the pin.

Correct me If I am wrong, but does it not insert into a hole that is supposed to be in the SIDE of the post of the nut and forced into the CS body by downward pressure applied by the slotted screw, thereby forcing it up against the CS body and stabilizing the CS screw in the body?

Seems like a good project for someone with a small lathe to make some of these.


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## mcload (Jan 19, 2021)

finsruskw said:


> Is the part number for the pin PT358NK1??
> 
> I am familiar with the conical end set screws as they are also used as bearing retainers on Cub Cadet mechanical PTO's
> And, since my last post, I have finally figured out just what the deal is with the pin.
> ...


Yes, that is exactly correct. Sorry, I don't have the part number offhand.
If using a new repro nut, there is a tiny bit of sharp burr where the pin exits the
nut. This has to be filed smooth or else the pin can hang up on it.

I can't imagine how difficult it would be to recreate that part; it is so very small!
Not only does it require a conical end and a straight slot, but the part that pushes
against the body has to have a convex end to match the curvature of the mounting hole!


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## mcload (Jan 19, 2021)

finsruskw said:


> I bought that manual (copy) from Grizzly and found it to be somewhat vague in some aspects.
> 
> The nut that was on my 9A was not drilled and there was nothing in the threaded hole, except petrified swarf
> The replacement nut was not drilled either.
> ...



Yeah I hear ya'. To total minimize that backlash, you have to replace the ACME thread too, which by the way, is kind of
hard to come by these days. It is an ACME 7/16-10 Left Hand Thread. McMaster Carr doesn't carry it. You can usually buy a
foot off the auction site, and I assume its made correctly.
   You basically have to cut the old thread off the shaft; drill and ream about an inch into that larger shaft; turn down
the new threaded rod to a slip fit; drill a small air-escape hole; saturate with a thread lock solution; push it in; allow to dry,
then drill and pin the tang into the body.  The guys that sell the repro CS nuts say they can do that for you, but
I don't know the cost....prob not cheap.
  That's why it so very important to keep those threads lubricated to minimize wear.


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## finsruskw (Jan 19, 2021)

I currently, with the new replacement nut, have about .012 backlash including about .003in the dial end that I can shim out (I hope)

So, maybe I should consider well enough??
Thank you very much for your input.
Very much appreciated.

Dave S.


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## SLK001 (Jan 19, 2021)

finsruskw said:


> Curious as to where you found that parts page?



There is a US Army Technical Manual for the 9" SB lathe, #TM 9-3416-235-14&P.  The manual is public domain material.  The copy I have is: ARMY_CL670Z.PDF.  Don't remember where I got it, but it was from a search.


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## Jim F (Jan 19, 2021)

mcload said:


> Hello all. I thought I would chime in on this subject as I own 2 South Bend 9" lathes and I am familiar with this part.
> First, the pin (shoe) on the side of the cross slide (CS) nut does indeed "lock" the nut to the side of the mounting hole. And
> by "lock" I mean it applies pressure to the nut to take up any play or movement that would show up as increased backlash.
> 
> ...


That is not a lube point. That is why there is no hole there.


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## mcload (Jan 19, 2021)

finsruskw said:


> I currently, with the new replacement nut, have about .012 backlash including about .003in the dial end that I can shim out (I hope)
> 
> So, maybe I should consider well enough??
> Thank you very much for your input.
> ...


You are certainly welcome. 

I'm not sure what the average backlash number was on new SB lathes from the factory, but I'm
thinking .005 or less. Clearly without a new ACME screw, I'd say .009 or 10 is probably right...but could be better or worse depending on how worn the ACME thread is of course. Replacing that ACME thread is pretty involved, and I'm personally wondering if I should do it myself on my machines. Problem is, you and I can get far too obsessed about a few thousandths of an inch when in all reality, it really won't make a bit of difference with the accuracy of our machines. We're talking about the width of a piece of paper!! (Most people wonder what in the hell is wrong with us!).  But I wouldn't blame you in chasing down that backlash either...it's part of the hobby; part of the disease!

But if you've got some time on your hand, it would do a world of good to drill an oil hole in the bottom of that nut to keep the threads from
wearing any quicker.

PMc


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## mcload (Jan 19, 2021)

Jim F said:


> That is not a lube point. That is why there is no hole there.


Okay, then how and where does the CS thread and nut get lubrication on a 9" and 10" Light lathe? (waiting)


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## Jim F (Jan 19, 2021)

There is a screw at the front that is labeled oil.
Just like the one on the middle step pulley of the head stock.
I had one of these laminated and it hangs behind my SB9.









						SOUTH BEND 9 LIGHT 10 10K OIL LUBRICATION CHART MACHINIST LATHE TOOL SHOP POSTER  | eBay
					

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## mcload (Jan 19, 2021)

Jim F said:


> There is a screw at the front that is labeled oil.
> Just like the one on the middle step pulley of the head stock.


With all due respect Jim, the tiny hole at the front of the casting is for oiling the CS crank mechanism shaft. There is no possible way that oil at that hole can travel the full 6" where the CS nut is. The oil hole at the step pulley is a different mechanism, and indeed, oil is delivered to the step cones. Look at the photo below with all the fine threads....you think oil is going to traverse 6 inches to the CS thread and nut? No sir, it won't.

Another fact is that on SB lathes larger than the 9's and 10's, there is a hollow bolt right above the CS nut for the specific reason of providing lubrication where the two threads interact. So why not for the 9's and 10"s?

Below are photos of the saddle assembly showing the exposed CS thread. Note that from the top, an owner has to completely remove the compound rest in order to oil the ACME thread, and it's still two inches from the nut. The threads are also exposed on the bottom, however, to oil here, a person would have to squirt through the bottom of the bed and through the webs into a small opening in the casting. How likely is either of those scenarios going to happen for the average user?

No, the most likely is that South Bend either forgot about a hole in the bottom of the CS nut, or didn't deem it important enough.
As a result, many hundreds of people have replaced the original CS nuts that have pre-maturely worn the ACME thread, with non-drilled 
reproductions that continue to wear the CS ACME thread. And all it takes is a tiny 1/8th inch hole at the bottom of the nut to deliver
much needed lubrication to meshing threads that are VITAL to the accuracy of the lathe. I don't think that's too much to ask for
an avid SB lathe owner to consider. Think about it, sir.

With All Due Respect

PMc


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## Jim F (Jan 19, 2021)

With all due respect, I am not as smart as the Obrien twins, so I follow their instructions.


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## mcload (Jan 19, 2021)

Fair enough; no problem.
BTW, I too have that exact lube chart next to my lathe as well.


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## finsruskw (Dec 30, 2021)

Ran across this the other day while researching a SB 14-1/2
Can one of you fellows with small lathes make some of these Tee Nut pins?

workshop_cross_slide_nut_pins.pdf (wswells.com)


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## graham-xrf (Dec 30, 2021)

Given the wartime need, a very widely distributed manual is, and always was, available to all who might need to keep a South Bend going. It has pictures aimed at maintenance assembly, so does not have dimensioned drawings, but is useful for parts lists. It covers old SB-9 and SB-10K


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