# SM9 Cross Slide Screw



## YotaBota (Mar 31, 2021)

This will be quick as the hard part has been gone over in, https://canadianhobbymetalworkers.com/threads/acme-threading-problem.3112/#post-40875.
I wanted to make a new screw not only because the lathe needed one but it was to add to my knowledge and experience.
I used .500 C1144 steel for the screw, it turned really smooth and the only surprise was how much better the steel is than the cheap cold rolled I used for practice.
The thread is a LH 10tpi acme so there was a bit of a learning curve, using a straight 90* plunge with the cross slide only worked well. The first .030 was cut in .005 increments, the next .020 was in .002 increments and then finished in .001 increments with a few of spring passes spread out in between.
Drilled the hole for the gear roll pin, milled the flat for the set screws and installed. Were there was .100+ movement with the old screw, there is only about .004 of movement.
The first pic shows the components of the screw.
The second pic shows the cut of the thread.
The third pic show the new and the old screw, the shadow really shows how much the original screw is worn.
All in all it was a great learning experience with lots of help form the clan here on the site, thanks all.


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## YYCHM (Mar 31, 2021)

That's about how my SM9 cross slide screw looked as well.  Luckily @Brent H sent me a better one and nut from our parts machine purchase.

Nice work!


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## David_R8 (Mar 31, 2021)

The difference in the shadows is remarkable.
Well done!


Sent from my iPhone using Tapatalk


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## YotaBota (Mar 31, 2021)

The threads in the nut look the same, sharp enough to cut yourself.
This was the second attempt, on the first try I miss stepped dancing the dials and ended up with one side of thread looking okay and the other side at about a 45* angle, oops.


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## RobinHood (Mar 31, 2021)

Great repair Mike. Keep it well lubricated and it should last a long time.


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## YotaBota (Mar 31, 2021)

Thank you sir, oil is cheap, use lots.


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## Hruul (Mar 31, 2021)

Great work Mike.  Attempting the nut next or already done?


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## 6.5 Fan (Apr 1, 2021)

Looks great. Lots of guys won't try threading SAE thread let alone acme.


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## YotaBota (Apr 1, 2021)

Thanks guys,



Hruul said:


> Attempting the nut next or already done


I made the nut a while ago and used it for the screw thread guage. I bought a tap from MPI tools out of the states, it worked well.


6.5 Fan said:


> Lots of guys won't try threading SAE thread let alone acme.


I don't know why people won't try threading, maybe they don't have a gearbox and can't figure out the gearing but the actual threading isn't that hard.


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## YYCHM (Apr 1, 2021)

YotaBota said:


> but the actual threading isn't that hard.



As long as the material you're attempting to thread co-operates


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## YotaBota (Apr 1, 2021)

And you don't misstep dancing with the dials, lol


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## Mcgyver (Apr 2, 2021)

that turned out really well, nice work


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