# Upgrade Tailstock LMS 3540 Lathe



## jjtgrinder (Oct 12, 2020)

I’ve worked on this project for several days, off and on.  If anyone has a Sieg SC4 / LMS 3540 lathe, this is an almost required upgrade to the tailstock.  A “face piece“ with a 4 mm key was made to replace the screw which guides the quil when using the tailstock. This does a much better job of enduring the lateral load imposed on the quill when drilling and so forth.  I also installed a thrust bearing inside the tailstock so that when you are drilling the crank action is very smooth.


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## addertooth (Oct 13, 2020)

It is always nice to see efforts to upgrade these mini-lathes to share features enjoyed by the "big boys".


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## higgite (Oct 13, 2020)

jjtgrinder said:


> If anyone has a Sieg SC4 / LMS 3540 lathe, this is an almost required upgrade to the tailstock.


I admire your work, but wonder why you thought it was needed. Did the guide screw get messed up or something? My LMS 3540 is 6 years old and I’ve not had a need to modify the tailstock. Yours is the first post I’ve seen on the subject. But, I’ll certainly keep this in mind if I ever see the need for it. Nicely done.

Tom


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## jjtgrinder (Oct 13, 2020)

higgite said:


> I admire your work, but wonder why you thought it was needed. Did the guide screw get messed up or something? My LMS 3540 is 6 years old and I’ve not had a need to modify the tailstock. Yours is the first post I’ve seen on the subject. But, I’ll certainly keep this in mind if I ever see the need for it. Nicely done.
> 
> Tom



I made this upgrade because drilling with larger drills above 1/2”, stepping up a 1/16” at a time, this allows a much smoother feed with the larger drills.  As mentioned by Addertooth above, this is how it’s done on larger American made lathes.  With the “guide screw” there was considerable less feed smoothness due to higher lateral loading on the keyway while drilling.  I also had to remachine the quill clamping parts for a better fit. The clamp pieces didn’t fit well and marred the quill. That also caused some problems with feed smoothness.  It feeds very smooooothly now.


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## higgite (Oct 13, 2020)

jjtgrinder said:


> I made this upgrade because drilling with larger drills above 1/2”, stepping up a 1/16” at a time, this allows a much smoother feed with the larger drills.


The largest drill I recall using on mine is 1/2”, so that might explain why I haven’t had problems with it. I’ll keep it in mind, though.

Tom


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## 9t8z28 (Jan 1, 2022)

jjtgrinder said:


> I made this upgrade because drilling with larger drills above 1/2”, stepping up a 1/16” at a time, this allows a much smoother feed with the larger drills.  As mentioned by Addertooth above, this is how it’s done on larger American made lathes.  With the “guide screw” there was considerable less feed smoothness due to higher lateral loading on the keyway while drilling.  I also had to remachine the quill clamping parts for a better fit. The clamp pieces didn’t fit well and marred the quill. That also caused some problems with feed smoothness.  It feeds very smooooothly now.


I also have a 3540 and was wondering if you shortened the tailstock casting to compensate for the extended quill guide?  I guess you could also add an extension to the shank of the tool but you might also be loosing quill extension.  On my 3540 I used a larger set screw and ground the end to a tight fit in the slot.  This made a big difference but I couldn't get it tight enough to remove all rotation of the quill but its a lot better.  I am sure your mod is far better.  
Now that I think of it, I have a digital caliper mounted to the quill and I only lost around an 1/8" so maybe I am wrong about loosing quill travel.  

I like your idea for the bearing mod.  Do you have any pics showing how you added the bearing?  I thought about doing this especially when using 7/8" and larger drills but never got around to it.  I know its an old thread but there aren't many conversations about this lathe on any forums.


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