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2 Piece Crossfeed Nut Idea

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
With rke[pler informing me on the cross slide lock for T/A, and then Cal showing me his link on the crossfeed nut here:
https://www.practicalmachinist.com/vb/monarch-lathes/adjusting-10ee-crossfeed-screw-backlash-172175/

. . .well designs are similar between my series 61 and what a lot of you guys use on a 10ee.

One thing bothers me a bit. I'm not in love with basically using a jacking screw to bend or distort the cross feed nut to try to adjust any slop.

The length of these nuts are pretty significant. Why not try to create a 2 piece nut ? Then adjust where crossfeed screw is wore least. Even with a freshly cut nut I'd guess at least a couple thousandths play where CF screw is wore least. And gradually get worse, over maybe a short time period.

Off the bat, let me say I'm not ready today. Probably need a month or a little more. Need to finish another project first. Then I need to go through my T/A and install it. With that done, I think I can get a better idea of travels, measurements, and such. Right now, I just want to roll the idea around and get some thoughts.

Looking at the nut off the 61 series, the hole with yellow paint is the oil passage for CF screw. The dotted line is crossing the hole where jacking screw is currently used to force nut down on adjustment.

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Instead of using that jacking bolt hole to jack. . . Imagine slicing the nut in half, directly on that hole. Now two nuts. And now jacking bolt is used as a wedge to drive the two nuts apart.

It does not necessarily have to be THIS exact nut. I could make two new nuts closer to equal length. However the nut taking the most work will be driving into work. . .
 
I think that'd work. I might pin the 2 halves together axially to prevent any rotation betwixt.

But, if it bothers you that much I'd suggest that you're better off cutting a new screw and nut. It's a pretty simple project, just need an acme ground threading tool.
 
Now looking at nut in relation to the holes in compound. The far right hole in compound is not related to the CF nut, it is to lock cross slide for T/A.

Also not seen, is oil passage to mate up to yellow hole on nut.

Far left hole, is bolt hole to retain nut, tight to compound.

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Now imagine drilling/milling a 3rd oval hole to retain 2nd nut. The oval hole allows for the future adjustment, as you drive down wedge bolt.

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I believe hole labeled 2 will take the load as driving into work. While the 2nd nut with oval see load on return.

This idea is all very rough. I don't know exact placement of holes yet. What travel may or may not interfere. More questions. I will know more once T/A is up, and CF screw.

Any opinions, ideas ? Has anyone tried before ?
 
I think that'd work. I might pin the 2 halves together axially to prevent any rotation betwixt.

But, if it bothers you that much I'd suggest that you're better off cutting a new screw and nut. It's a pretty simple project, just need an acme ground threading tool.

Short term it does not bother me. Its the idea I'm going to take some effort and cost to make a new nut. . . and I'm still going to see slop on dial if one piece. :D
 
I would try to make a new nut that would bolt on to the existing nut and snugging the bolts against jack screws to eliminate the backlash, like as mentioned earlier, a smaller version of BP mill table split nut. That way no drilling into the machine. It might take a looong screwdriver to adjust the screws if you could access them at all?
 
It definitely would work. My Barber Colman #3 has an adjustable leadscrew nut that is tightened to eliminate backlash, a pre-ballscrew way to accomplish climb hobbing. Even the Sherline mill has backlash adjust nuts.

But why? Lathes in general don’t have a backlash issue. I’m all for minimum play, but all three of my lathes, 1947, 1949, 1956 have play in the crossfeed, and they all work very well.
 
But why? Lathes in general don’t have a backlash issue. I’m all for minimum play, but all three of my lathes, 1947, 1949, 1956 have play in the crossfeed, and they all work very well.

On any given Sunday. . .I would not take it apart just to do this. Basically 2 reasons. One, it is already apart. Two, I need to make a new nut, regardless one or two piece.

I was thinking I'm already into it for the tap, then I'm going to need a decent size piece of 932 bronze. . .

Going the extra step is not that much further of a reach. Might reduce my stress on tap too, two shorter vs a single long hole to tap.
 
On any given Sunday. . .I would not take it apart just to do this. Basically 2 reasons. One, it is already apart. Two, I need to make a new nut, regardless one or two piece.

I was thinking I'm already into it for the tap, then I'm going to need a decent size piece of 932 bronze. . .

Going the extra step is not that much further of a reach. Might reduce my stress on tap too, two shorter vs a single long hole to tap.

There are a lot of good options mentioned here. An adjustment for older printnng presses I ran the adfustments for registration would wonder back and forth if there was slop.

We did what Rob F mentioned. Two nuts jacked against each other. It was open screw shaft so it was easy to tweak it just right. It was a spring loaded rig.
Whatever you do wear is an ongoing issue with adjustments. I hated that when making fine adjustments. You become accustomed to working with it but never like it.

But I understand your quest and I am on the same page in tightening up adjustments.
With your series 61 you could come up with a good design for a nut and produce and sell a few. Thread some acme cross feed screws and compound screws while your at it. I would think you could sell a few. Specialty item.
If cross feed screws and compound screws were easier to keep clean and oiled it would help.
They create their own slurry that speeds up wear. Drops of oil on the screw helps but really don't cut it.

When I get familiar with the 10ee I'm going too make a new screw and nut for an old Cincinnati lathe I have. Mastering threading is a goal of mine. I've had mixed success on the SB.
 
This is how Sioux took the slack out of a feed nut, seems pretty simple, and with a little creativity the concept could be applied to a machine that never had an adjustable nut. Both pieces are threaded, spring keeps tension between them.
 

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This is how Sioux took the slack out of a feed nut, seems pretty simple, and with a little creativity the concept could be applied to a machine that never had an adjustable nut. Both pieces are threaded, spring keeps tension between them.

And the pin locks the adjustment nut
 
And the pin locks the adjustment nut

The long piece attaches to table, I would call it the fixed nut, the other piece is just along for the ride, I will call it the floating nut, the pin keeps the floating nut from spinning so that spring pressure is maintained on the fixed nut. I can see how this could be reconfigured for a tighter application like a feed nut on a lathe where there is no space for the arm.

Edit: Playing with this idea in my head for one of my machines, to make it as compact as possible I'm thinking use a wave washer between fixed nut and floating nut.
 
The spring loaded tension works well. Keeping it all within the margins so that it doesn't affect travel distance is the trick.
A recess could be cut so the spring goes partially into or over or into a grove cut into the nut. Against a sholder to use less space.
That does make a controllable adjustment.
 
The spring loaded tension works well. Keeping it all within the margins so that it doesn't affect travel distance is the trick.
A recess could be cut so the spring goes partially into or over or into a grove cut into the nut. Against a sholder to use less space.
That does make a controllable adjustment.

Texasgunsmith
I didn't intend to shoot a hole in your two piece nut with a wedge. Its a problem that's been worked over many times. I have a cross feed nut that someone cut about 3/4 through the center and put a jackscrew to spread the gap. That's similar to your idea accept your wedge would separate the two halves instead of distorting the threads.

As well as these lathes are made I believe the manufactures just expected owners to replace them. They have to sell some replacement parts too keep the doors open.
Also its a part that gets constant use. I doubt most were oiled daily as the book says. Or every 8 hour shift.
I'm curious about if you started new with one and if it was oiled as recommended how long they stay tight. Cleaning with something like a brake cleaner monthly could help. Or blow swarf in deeper?

I mentioned sloppy adjustments to a boss one time. He said we pay you to make it work.
My machinery was 40 to 60 feet long with a half dozen adjustments at six stations. All with a different amount of wear. You learn every handle. Aggrivating though. It does cost some product loss. My job title was ,Machine Adjuster.
Really just a knob twisting S.O.B.:D


Are there any lathe owners that bought new that have an answer on how long they stay tight? Hours of use would be a determining factor. Too many variables?
 
Wouldn’t the spring compress under heavy load? I guess on a cross slide this could be configured for the lighter loaded retraction, except that would make using a boring bar sloppy. You could use a spring heavier than the worst case load but that would wear your leadscrew quickly. Am I missing something? A jam nut, if tightened only to just taking out slop, seems like a more rigid approach
 
Texasgunsmith
I didn't intend to shoot a hole in your two piece nut with a wedge. Its a problem that's been worked over many times. I have a cross feed nut that someone cut about 3/4 through the center and put a jackscrew to spread the gap. That's similar to your idea accept your wedge would separate the two halves instead of distorting the threads.

As well as these lathes are made I believe the manufactures just expected owners to replace them. They have to sell some replacement parts too keep the doors open.
Also its a part that gets constant use. I doubt most were oiled daily as the book says. Or every 8 hour shift.
I'm curious about if you started new with one and if it was oiled as recommended how long they stay tight. Cleaning with something like a brake cleaner monthly could help. Or blow swarf in deeper?

Are there any lathe owners that bought new that have an answer on how long they stay tight? Hours of use would be a determining factor. Too many variables?

I don't mind, shoot away ! :D I made a joke at Cal in the other thread, because he twice guessed correctly the direction I was going, before I posted it. :D He must have a 6th sense on these things.

Really I wanted feedback anyway, so I appreciate it. I'm an easy month from getting to it, so it gave time to collect some ideas.

While I expect to use the lathe, I doubt I would log enough hours in my life to wear out a 1 piece. And this is kind of machine, I expect to care for.

In my head when starting this, I was less worried about chatter in cuts, I was thinking of dials that have half of a turn slop, going one direction to the other. Though that should not be my only consideration.
 
Wouldn’t the spring compress under heavy load? I guess on a cross slide this could be configured for the lighter loaded retraction, except that would make using a boring bar sloppy. You could use a spring heavier than the worst case load but that would wear your leadscrew quickly. Am I missing something? A jam nut, if tightened only to just taking out slop, seems like a more rigid approach

Yes, I think you have a point, and was on my mind too. Off course I'm theorizing here, not actual trial and error. But I was thinking a spring type as shown, would be nice for reducing some chatter, but depending which side the spring is pushing. One side be better for straight in OD cuts.

Spring on the opposite side would be better for boring, where you're pulling the compound back.

That's my guess, or theory anyway.
 
The Monarch doen't have it because it took ages to wear-out, and then one simply replaced BOTH screw and nut. Might not be obvious until you get to fitting it, but the Monarch design lets you run straight and loose, then cock the nut off-line with but handy tools to provide a temporary tightening to reduce backlash.

AND then.. take the sidegodlin stress back out for less demanding tasking so as not to make wear-rate worse than it is already.

NB; Backlash doesn't much bother me. Never had a decent lathe, company owned it, I just ran it "as had".

Need one for the 10EE's, Brian Miller, Miller Machine & Fab makes better ones than I care to try to match.

Monarch Lathe is worth checking with. They are not "overpriced" unless actual 2020 costs, not 1940 costs require them to charge prevailing rates for things they may have to do from scratch off really old prints.

You're right, I hadn't considered adjusting, then un-adjusting.

And all in all, I could probably run the old nut no problem. The weight of the machine, and all the parts, I don't really expect it to bounce around on work.

Right after I received the mt5 test bar from Brian, contacted him about this nut. He asked for a pic, said he needed to check if he had the acme tap. He didn't get back to me, so I'm guessing no. I did not try Monarch, probably should have, but I bought the tap, so I'm invested now, unless I break the tap during. :D
 
Wouldn’t the spring compress under heavy load? I guess on a cross slide this could be configured for the lighter loaded retraction, except that would make using a boring bar sloppy. You could use a spring heavier than the worst case load but that would wear your leadscrew quickly. Am I missing something? A jam nut, if tightened only to just taking out slop, seems like a more rigid approach


The spring was strong but we could adjust. A jam nut locks the nut so no jam nut used. Oil helps the wear. You have to use experience and common sense as to pressure added.
The spring may not work on a lathe. Good point.
Jackscrews are often used. Your pressing , how hard? Depends on the arm doing the twisting.
At that point wear is the downhill slide and your doctoring.

The pressure of a cutoff must be a hefty push against the threads while cranking in. That's more likely when more wear happens. Facing?
There are many here that know better than myself. Keep it clean and well oiled if you can get too it. Its hidden from cleaning on most lathe's
That slurry of oil ,ground bronze and steel eats at it. It is better than dry .
Ball screw ! Not 0n old monarch's but maybe a future fix.
 








 
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