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9" Cross Feed Nut Replacement

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Help crew; I hope all are well.

Getting close to finishing my 9B project lathe, or so I hope.
Finally got around to dealing with the cross-feeds; and have the two handles
buffed up and shiny. But looking at the cross-feed nut, it looks like
hammered dog-shite. There is also evidence that someone has been at the
adjustment screw itself in the past, I assume that with a bit of heat, I'll be able
to back it out along with the "pressure pin" (for lack of the correct term).

I have a new nut on order and I hope it makes any backlash it had to a tolerable
amount. (Sorry, I don't know how good or bad it was before disassembly. I guess I
could easily find out though). As far as I can tell, the ACME screw looks okay, but
I'm sure it is worn somewhat.

I'm really disappointed that the original 7/16-10 left-hand ACME thread has gone the way
of the Dodo bird and is no longer available (McMaster), otherwise I might be compelled
to replace the screw as well. (I read the other threads on this procedure and it seems
easy enough). For those shouting at me to make my own ACME thread, I must say
that I don't have the confidence in doing so, and would much rather purchase a piece
of alloy thread produced on a CNC machine. (Yes, regular pointy threads I can do).

There is a chap that is selling a kit containing the correct screw and nut (good for him),
but I didn't want to resort to that just yet. Thought I'd see what replacing the nut alone will do.
Was thinking of a version using ½-10 LH ACME, but that's probably just a rabbit hole
I should stay away from.

Cheers.

PMc

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Dobermann

Hot Rolled
Joined
Jan 2, 2014
Location
North Carolina
I'm not sure if this is directly applicable to the 9" Workshop lathe but I did replace the crossfeed screw and nut in my 9" Junior lathe with a piece of commercial 1/2" X 10 Acme threaded rod along with an Acme nut which I machined to fit into the carriage. It works perfectly well and I believe (but don't know for certain) that there is room there in the 9" workshop for a 1/2" diameter screw. Of course you'll be more or less on your own so far as making a "store bought" nut fit into the carriage.

You'll have to do some machining of the screw piece to fit the bore in the carriage and to fit the dials but...you alreay have a lather for that!
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Help crew; I hope all are well.

There is also evidence that someone has been at the
adjustment screw itself in the past, I assume that with a bit of heat, I'll be able
to back it out along with the "pressure pin" (for lack of the correct term).

I don't know 9's at all, and in looking at some parts and pieces previous, I think they do some things different than a 16".

I'm asking because you said adjustment screw, and that could be correct for a 9. If you are talking about that flat head screw in center of crossfeed nut.

But on a 16" you remove that screw to shoot oil inside to lube threads of crossfeed nut and leadscrew. And a 16 would have a felt inside, below the flat head screw.

I'm wondering how the "pressure pin" works. What does it do ?
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
I don't know 9's at all, and in looking at some parts and pieces previous, I think they do some things different than a 16". I'm asking because you said adjustment screw, and that could be correct for a 9. If you are talking about that flat head screw in center of crossfeed nut.
I'm wondering how the "pressure pin" works. What does it do ?

Let me first say thanks to those that have responded, but I apologize for wasting your time on
this useless thread. Unfortunately, the Auto-Spell feature changed my "Hello crew.." to "Help crew..".....dammit!
I need to turn this feature off!

Replacing the brass cross-feed nuts during a rebuild is one of those things you just
do regardless of whether or not you think they need to be. Just like replacing pads
on a brake assembly during rebuild. I've replaced a few of these already, so there
was really no "call for help".

But to answer Texas Gunny's question, the "pin" is actually better described as a "shoe"
that moves laterally when the vertical screw is tightened down. This small lateral movement
presses the shoe against the wall of the mounting hole, essentially locking the assembly
in place. The bottom end of the vertical screw and the end of the lateral shoe (where they meet) are both cut with 45-degree angles. Once tightened during assembly, these pieces are never removed nor adjusted, and over a period of decades, simply freeze up. Hence, a buggered-up
screw slot (by someone) as seen in the photos.

So it will take some heat to free these pieces up, and I'll probably have to cut a deeper slot
in the screw just to get a a good bite on it. I'm thinking of maybe replacing the slotted screw
with an Allen-head set screw. The lateral pin will eventually punch out and will be polished
smooth so that it moves easily in its hole. I'm thinking a ball end on the pin might be a better
shape instead of a 45.

Anyway, that's it....clear as mud? My reason for posting really centered around the
lack of replacement 7/16-10 LH thread Acme thread. :angry:
Sorry for bumping this back up; let's just let it die a slow death!

PMc

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texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Regardless your intention for the thread, I learned something, well worth it !

It seems that side pin is what locks CF nut to compound. A 16" uses a different method, where a hollow bolt is threaded into CF nut, and they tighten together as a normal nut and bolt would to squeeze tight on the compound. The bolt being hollow to allow oiling of CF screw threads.

Just a curiosity, how do you lube CF threads on a 9 ? I'd be curios if there was room for oil to slip past that side locking pin. Maybe a small hole continues down past that side pin and into threads of CF nut. Is it possible to remove that flat head screw from the top and lube that way ?
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Regardless your intention for the thread, I learned something, well worth it !
Just a curiosity, how do you lube CF threads on a 9 ? I'd be curios if there was room for oil to slip past that side locking pin. Maybe a small hole continues down past that side pin and into threads of CF nut. Is it possible to remove that flat head screw from the top and lube that way ?

That my friend is a very good question for which I don't have an answer.
Yes, you would think a hollow bolt would provide that lubrication to the threads, but sitting where it does on the saddle,
that opening would collect a lot of swarf unless there was someway to cover it. I do NOT believe the vertical hole
extends into the threads section,
I'll have to think about that....very good point!

PMc
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Oiling the Cross-Feed Threads and Nut on 9"

I completely erased a reply I had here as I was making mountains out of molehills!

Clearly, the BEST way to oil these threads is THRU that slotted screw that sits
on top of the nut. It just so happens that I had another used nut to inspect. I removed the
slotted screw and inserted a wire, The hole does NOT go through into the threads
in the nut!

So, a simple ⅛" or 3/16ths hole drilled down into the nut threads is all that will be
required. Simply unscrew the slotted screw, squirt in some oil and work it into the
length of the threads, then retighten the screw.

Like Gunney's set-up, a hollow bolt could work too and maybe a ball-oiler on top of that?
But drilling through the nut is the answer!

Problem solved; easy-peezy. I'm now wondering why SB neglected to do this on the 9" lathes?!

PMc
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
I'm working right now, but when i get back I'll post some pics of the 16 pieces. Might give you some ideas.

On a 16 that vertical oil hole is not cleanly drilled if i recall. It just pierces two of the low points of CF thread, leaving the high points of threads.
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Just a curiosity, how do you lube CF threads on a 9? Is it possible to remove that flat head screw from the top and lube that way ?

Lord knows I am not the sharpest tool in the shed. But I have to give you kudos for asking this question
in the first place. Had you not, I wouldn't have thought to question it myself. And with all due respect, I wonder how many other hundreds of owners of 9" SB lathes ever thought about it either, especially when neither the OEM cross-slide nuts nor the replacements have an oil hole thru the top directly to the threads. The requirement for lube is also important due to the fact that the cross-slide thread size is essentially no longer easily available.

So I appreciate your inquisitive mind, sir, as this has some long-reaching implications for all 9" lathe owners.
Feel free to bump yourself up to "titanium" status, and send me the bill!
(now need to turn my sights on lube for the compound rest threads, if that's even possible!)

PMc
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
So I appreciate your inquisitive mind, sir, as this has some long-reaching implications for all 9" lathe owners.
Feel free to bump yourself up to "titanium" status, and send me the bill!
(now need to turn my sights on lube for the compound rest threads, if that's even possible!)

PMc

I wish I was that smart, I'm just lucky to have it stamped "oil". :D

To show you how smart I am, I dropped my flat head screw into the chip pan, more precisely, somewhere in the chips in the chip pan. :D For now I stuck a 1/4" bolt in the hole to keep chips falling down the hole.

39.jpg

A look at a CF nut, with the hollow retaining bolt that is used to tighten to compound:

40.jpg

Looking vertically down the hole, it was indeed not drilled all the way. It appears careful drilling to just pierce the valley of a CF thread, note the slot of CF thread at bottom, the two sides of that slot are the peaks of the CF thread.

41.jpg

I think you could probably do the same for sure, if you get oil around the shoe/side pin pieces.

Compound rest I can only put oil to the screw, not the same as the CF. But if you notice the set screw in middle of compound rest, removal of that screw allows oil to drop onto that feed screw. I would guess you could do the same by drilling and tapping for a small set screw:

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A bit off topic, but part of your thread was replacing atleast CF nut to tighten it up some. Its been on my mind as well. I hate slop in the handwheel, which some will happen regardless, even with new parts. Where you turn the handwheel in one direction, but reversing direction you get X amount of thousandths reading on dials before CF begins to move. And when you have wear, it could be like a 1/4 turn of handwheel :D.

I first had the idea from a mill I'm working on. This particular mill has what appears to be two CF nuts on the same lead screw. The idea being, the two nuts are adjustable. You adjust them to oppose each other, draw them apart from each other, until that slop is reduce to near zero.

To do the adjustment, you need to adjust at the least wore portion of lead screw. If you adjust at a heavier wear section, then getting to a good clean section of lead screw, it will be too tight. Not perfect, but an inventive way to reduce some slop.

Well I plan a mod on another lathe to do just that. And in doing some research and discussion with other members, mllud22 found a print of a Pacemaker lathe, and the CF nut is actually 3 pieces, two nuts, and a wedge in the middle. By drawling the wedge up, it separates the two nuts, removing some slop. The yellow are the two nuts in drawling, orange naturally is the wedge:

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mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Looking vertically down the hole, it was indeed not drilled all the way. It appears careful drilling to just pierce the valley of a CF thread, note the slot of CF thread at bottom, the two sides of that slot are the peaks of the CF thread.

Not to beat this thread to death, but I can see what appears to be more of a wedge-shaped slot than a hole
in your photo. I can't see what drilling thru (all the way) an 8th inch hole as opposed to only breaking thru the thread
valley could hurt. I won't be able to get that precise with a drill press anyway.

Nope, don't have a ball-oiler halfway down the compound rest. I backed the rest all the way out and looking upside down, can see the threads and nut, so I will be able to oil it on occasions with an acid brush dripped in oil.

Thanks for pics and suggestions!

PMc
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Not to beat this thread to death, but I can see what appears to be more of a wedge-shaped slot than a hole
in your photo. I can't see what drilling thru (all the way) an 8th inch hole as opposed to only breaking thru the thread
valley could hurt. I won't be able to get that precise with a drill press anyway.

Im guessing, but was thinking two possibilities on why drilled that way. One, a smaller opening would prevent chips falling directly on screw if I was clumsy oiling. Two, maybe to not create a debris collection point for the feed screw.

Either way, a small drilled hole may solve that.

If your drill press has a depth stop screw, you could incrementally drill down precise, if holding part in a vise on its table.

Not knowing if point of drill bit was over a peak or valley of thread might be a problem, but an end mill type drill bit might solve that.

Whatever road taken, I'm sure getting lube will add to longevity, and probably nice, clean movement.
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Final

Just thought I'd post another few pics of the cross-slide nut I took last night, along with some tips.

First, by the photo, you can see how the vertical screw comes down and pushes the steel shoe laterally. This shoe is what essentially "locks" the nut into it's mounting hole and provides pressure to keep the nut free of any movement that would show up as backlash. Over the decades, this shoe will seize in its' hole, and will take heat, a punch, and some 90-degree leverage to push out.
Same with the screw, actually.

It is very important that when replacing the nut, this shoe is free to move in and out. I found that
I had to carefully file away the sharp edge and burrs at the opening of the hole on the new replacement nut. Small fine, half-round jewelers file does the trick. (Just make sure you don't drop it on the floor as it will be impossible to find!).

The shoe itself needs to be polished too. I found that the chuck in my hand drill was perfect for grabbing half of it, spinning it, and using 1000 grit wet/dry to polish. Turn it around and do the other half. Same with the screw. I was able to grab it by the threads, and then clean-up the top face and side bevel first with a flat jewelers file, followed by 1000 W&D.

I tested the screw in the threads first though and found it got tight and stopped a bit too short for me. I first tried using a 5/16-24 die, but I couldn't seem to get it to start right. I then went to my trusty Snap-On Thread Restore set and took that appropriate die. It started nicely and I was able to clear and conform the rough threads. (That restore set is a MUST for anyone doing this kind of work!).

I drilled a 1/8th inch hole into the CS threads for the above mentioned oil hole. I followed by using a round brush (similar to a brush you would find in a gun cleaning kit) to clear out any debris and burrs. I did an oil-flow test and the hole did a great job of dispersing the oil into the threads. Now all I have to do is occasionally remove the screw, squirt in some oil, work it back and forth, and retighten the screw.

I finally mounted the nut in the small 4-jaw I have, then cleaned and polished the top just for the hell of it. So it's now ready for installation today. There is a bit of curved grind on the shoe, so be sure to match it with the hole

PMc

BTW, Napa and or Craftsman makes these identical kits for a lot less money. My only complaint is that they start at ¼" and don't include the smaller screw sizes like 12's, 10's and 8's.
https://youtu.be/FRqKkcmlt0A

Also, I had and used a screw with a better head/slot than what is shown in first photo below.


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SLK001

Stainless
Joined
Feb 8, 2015
Location
Coral Springs, FL USA
That screw in the top of the nut is REMOVED to oil the cross feed shaft (then replaced). If it is frozen on, then the shaft has been starved of oil for years (decades?), hence the reason for a very worn shaft.
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
That screw in the top of the nut is REMOVED to oil the cross feed shaft (then replaced). If it is frozen on, then the shaft has been starved of oil for years (decades?), hence the reason for a very worn shaft.

Normally, you would be correct, especially on larger SB lathes such as Gunny's 16" that he so aptly illustrated, showing a hollow bolt for oil.

However, on 9" lathes, that is NOT an oil hole and therefore rarely if ever gets removed. On both original South Bend CS nuts as well as replacements, there is no hole directly to the CS threads. (I've checked both). Perhaps owners of 9" lathes thought they were oiling their CS threads, but I'm afraid it isn't so. So there really isn't any reason to remove it at all, is there?

As explained in above thread texts, the answer is to drill a 1/8th inch hole through the bottom of the nut and into the internal threads. Then and only then can the CS threads receive much needed oil.

Thank you for your input.

PMc
 

SLK001

Stainless
Joined
Feb 8, 2015
Location
Coral Springs, FL USA
However, on 9" lathes, that is NOT an oil hole and therefore rarely if ever gets removed.

Are you sure about that? Every piece of SB lit about oiling says to oil the cross screw by removing the screw in the bearing. Is the hole for the screw not drilled into the ACME threaded area?

If that ISN'T the oiling port, then where is it? I don't have a 9", so I can't verify this myself.
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Are you sure about that? Every piece of SB lit about oiling says to oil the cross screw by removing the screw in the bearing. Is the hole for the screw not drilled into the ACME threaded area?

If that ISN'T the oiling port, then where is it? I don't have a 9", so I can't verify this myself.

From post #8:

Clearly, the BEST way to oil these threads is THRU that slotted screw that sits
on top of the nut. It just so happens that I had another used nut to inspect. I removed the
slotted screw and inserted a wire, The hole does NOT go through into the threads
in the nut!

While I don't 100% know, maybe the nuts mcload had both happened to be aftermarket, let's say originals replaced somewhere in the lathes mid-life. New guy who made the aftermarket nuts does not know it takes an oil hole. . . Again not sure, I just think a possibility. Plus no "oil" stamping on compound, compounds the problem ! Ha, a play on words !

Or maybe 9 owners were supposed to shoot oil up from under the bed, but I've not read that anywhere.
 

mcload

Hot Rolled
Joined
Nov 5, 2007
Location
Houston, Texas
Are you sure about that? Every piece of SB lit about oiling says to oil the cross screw by removing the screw in the bearing. Is the hole for the screw not drilled into the ACME threaded area?

If that ISN'T the oiling port, then where is it? I don't have a 9", so I can't verify this myself.


Please see photo exhibit A. I have 3 CS nuts total. The first two are clearly cast and have numbers stamped into them. The third on the far right is a recent reproduction. None of the 3 have small oil holes leading into the CS thread section.

So are these first two actual SB produced nuts that were fitted to my machines? It would strongly seem so. The one on the left was just removed from my 1958 Model B 9". The middle one is from my 1946 Model A 9", and the far right is the newly purchased reproduction.

The only hole marked "oil" is at the front of the CS casting, and is clearly used for the CS thread handle crank mechanism. The CS nut is a full 6" away from this little hole.

And it is virtually impossible to shoot oil underneath without taking a lot of parts off.

So you tell me. All I can go by is what I've taken off the lathes. Perhaps there are some other owners out there who are in a position to check their own machines. All they would have to do is unscrew the screw and check for a hole with a wire. Inquiring minds would like to know!

PMc

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SLK001

Stainless
Joined
Feb 8, 2015
Location
Coral Springs, FL USA
So you tell me. All I can go by is what I've taken off the lathes. Perhaps there are some other owners out there who are in a position to check their own machines. All they would have to do is unscrew the screw and check for a hole with a wire. Inquiring minds would like to know!

I'm with you and am shocked by the lack of an oil port on the 9" lathes. I'm wondering just how 9" owners oil their cross slide screw. Or, is the cross slide screw just a disposable part?
 








 
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