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Strange Lathe Thread

jdrichard

By jdrichard
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jdrichard Distinguished Member

jdrichard

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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 Distinguished Member

jdrichard

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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: Update3f31b917a9655cba8a1fc9d2e0c6f183.jpgb2c556ff6c46f3b92effb614b0c56109.jpg323e2c54ac26e6dcf9aef3ab5bad2db3.jpg34dbc14cf344fef5409a8adb67e78695.jpgFlattening the peeks
dd455a561809a6104ff4bd3796f93719.jpg9f45b7e79411a529559c3094794ac748.jpg
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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Deggsie WRT Addict

Deggsie

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

2444eb5befd09e50d2077a8cdf6a9a41.jpg
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

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vinn3 Distinguished Member

vinn3

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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

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measuretwice WRT Addict

measuretwice

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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 :)

 

 

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jdrichard Distinguished Member

jdrichard

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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 Distinguished Member

jdrichard

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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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