Strange Lathe Thread

[jdrichard]

I have a Boley Leinen Reform Lathe that has a nut that you adjust to tighten and loosen the lathe spindle bearings. The thread on the male part of the spindle shaft are flat on the top. Like the top of the mountains have been chopped off. The mating thread on the nut also has the mountain peeks chopped off. Any guess what the reason. The TAP is a 1/2” 20 TPI SAE. And i need to make a nut that is tighter fitting.

 

 

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[jdrichard]

This is the nut


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[jdrichard]

This is the start of my alternate nut that i need to complete and tap and somehow cut the peeks off the mountains.


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[watchabit]

Make the hole a little bigger to take the tops off the threads? Or don't cut the threads as deep? I'm sure you already thought this as its obvious, so I'm mostly asking questions. They look a little like acme threads. 

[rodabod]

A German lathe with an American thread?

Edited March 16, 2018 by rodabod

[jdrichard]

A German lathe with an American thread?

This is a German lathe, however, the thread is a SAE 20 on my two sets of gages

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[vinn3]

those threads appear to be a form of  "acme thread pattern"..  all the specs are in the "machinery hand book".  vin 

[jdrichard]

those threads appear to be a form of  "acme thread pattern"..  all the specs are in the "machinery hand book".  vin 

What the Heck is an acme thread pattern...Willi coyote??


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[vinn3]

3 hours ago, jdrichard said:

What the Heck is an acme thread pattern...Willi coyote??


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    it is something a machinest would know,    quite common on lathes.  vin

[watchabit]

Found on screw jacks, spring compressors and the like, for lifting heavy loads. I'm sure Wiley has in fact, used a few

[watchabit]

And yes lathes, table saws, long acme threaded rod for adjustment. 

[rodabod]

As JD says:

[rodabod]

Also, is your plan to make a lock-nut to bind the existing nut against?

[jdrichard]

Also, is your plan to make a lock-nut to bind the existing nut against?

Replace an the existing nut with one that binds. Almost done: UpdateFlattening the peeks

Still need to shave it down a bit and then cut it on one side and compress it slightly

How springy is brass and should i heat it before i compress it a bit?


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[jdrichard]

Finished the locking nut and adjusted it so that in is tight against the Headstock and holds everything tight. Not sure if i need to cut the slot and crimp the ring a bit????


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[jdrichard]

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[Deggsie]

On 16/03/2018 at 1:16 AM, jdrichard said:

This is the start of my alternate nut that i need to complete and tap and somehow cut the peeks off the mountains.


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it looks like something called a butress thread

[jdrichard]

it looks like something called a butress thread

Interesting. Wide thread makes it mot durable.


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[vinn3]

  an acme thread tap -- is available at a tool supply  or borrow it from a machinist friend.  vin

[vinn3]

17 hours ago, jdrichard said:

Interesting. Wide thread makes it mot durable.


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    well,  the point is,  it is not a simple or a common thread.  "by any other name"  it's not easy to  duplicate without a machine shop.  vin

[jdrichard]

Off again to make another one, but this time a bit narrower and thinner to get a spring action. Still not sure how to temper brass into a spring action. Have bought a few books and will research.


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[measuretwice]

On 3/16/2018 at 6:31 AM, rodabod said:

A German lathe with an American thread?

no kidding....I'd almost be willing to bet the lathe its a 12 x 1.5 thread.   Give a 12 x 1.5 tap a try.

Acme?  Buttress?  easily identified with a straight on shot of the male thread but I'll go double or nothing on the lathe bet they're not .  If anything it would be trapezoid because its German but the pitch is way too fine, and there is no reason for it in that application.  Afaik you don't see many buttress threads outside of collets and the odd vise screw.

Why do you need the nut tighter?  Afaik its suppose have two nuts so you can lock them, i.e. staying in its spot isn't a function of the nut being tight on the shaft.  You can't really have a nut tight on a screw, there has to be clearance or it won't turn.  If its sloppy, that means too much clearance - you need a tap with a smaller pitch dia (taps are sold for the different classes of thread fit).   But i'm betting the issues the wrong thread identification.

If you did want to make it tight on the screw, you'd have to split, pry it open slightly, then thread which you can do with a tap.  Its not really a practical solution imo....when you do have to lock a nut on a thread you do so with small set screw with a brass underneath (ala Schaublin and Aciera)

End of the day I'll bet the solution is simple - a 12 x 1.5 nut that fits much better.  Make two so its a lock nut arrangement

 

 

Edited March 21, 2018 by measuretwice

[jdrichard]

no kidding....I'd almost be willing to bet the lathe its a 12 x 1.5 thread.   Give a 12 x 1.5 tap a try.
Acme?  Buttress?  easily identified with a straight on shot of the male thread but I'll go double or nothing on the lathe bet they're not [emoji4].  If anything it would be trapezoid because its German but the pitch is way too fine, and there is no reason for it in that application.  Afaik you don't see many buttress threads outside of collets and the odd vise screw.
Why do you need the nut tighter?  Afaik its suppose have two nuts so you can lock them, i.e. staying in its spot isn't a function of the nut being tight on the shaft.  You can't really have a nut tight on a screw, there has to be clearance or it won't turn.  If its sloppy, that means too much clearance - you need a tap with a smaller pitch dia (taps are sold for the different classes of thread fit).   But i'm betting the issues the wrong thread identification.
If you did want to make it tight on the screw, you'd have to split, pry it open slightly, then thread which you can do with a tap.  Its not really a practical solution imo....when you do have to lock a nut on a thread you do so with small set screw with a brass underneath (ala Schaublin and Aciera)
End of the day I'll bet the solution is simple - a 12 x 1.5 nut that fits much better.  Make two so its a lock nut arrangement [emoji4]
 
 

I think i found the final solution

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[jdrichard]

no kidding....I'd almost be willing to bet the lathe its a 12 x 1.5 thread.   Give a 12 x 1.5 tap a try.
Acme?  Buttress?  easily identified with a straight on shot of the male thread but I'll go double or nothing on the lathe bet they're not [emoji4].  If anything it would be trapezoid because its German but the pitch is way too fine, and there is no reason for it in that application.  Afaik you don't see many buttress threads outside of collets and the odd vise screw.
Why do you need the nut tighter?  Afaik its suppose have two nuts so you can lock them, i.e. staying in its spot isn't a function of the nut being tight on the shaft.  You can't really have a nut tight on a screw, there has to be clearance or it won't turn.  If its sloppy, that means too much clearance - you need a tap with a smaller pitch dia (taps are sold for the different classes of thread fit).   But i'm betting the issues the wrong thread identification.
If you did want to make it tight on the screw, you'd have to split, pry it open slightly, then thread which you can do with a tap.  Its not really a practical solution imo....when you do have to lock a nut on a thread you do so with small set screw with a brass underneath (ala Schaublin and Aciera)
End of the day I'll bet the solution is simple - a 12 x 1.5 nut that fits much better.  Make two so its a lock nut arrangement [emoji4]
 
 

So i could buy a 12x1.5 nut, correct? And cut it and make it sprung. The nut hole is a 29/64 inch prior to taping.


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[jdrichard]

Last note: picked up a nut today and it fit perfect. Need to cut it and compress it a bit. Still confused as i don’t think it is an acme thread


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