Lathe cross slide conversion to a ball screw

I had a lot of backlash in the cross slide feed screw, which made it inconvenient to use and difficult to turn accurately. I have had the notion to change it to a ball screw running around in my mind for quite some time and recently I bit the bullet.

Here is a video link: https://youtu.be/3aW7tl91rq0

The original lead screw was 15 mm in diameter, the ball screws came in 16 and 14 mm. I choose the 16 mm which was a mistake, you can see in the video how much I had to cut off the ball nut to get it to fit. The 14 mm size would have made that easier and still been perfectly adequate. We live and learn.

I am over the moon with the results of the conversion and have no hesitation in recommending it to anyone. There were some tricky setups needed to machine things accurately but they are fully explained in the video. Here are a few stills.

Attachment 38198 Attachment 38199 Click thumbnails for full size.

Attachment 38200 Attachment 38201

Attachment 38202 Attachment 38203

Excellent work Tony - and explanations are very good throughout, IMHO.
For a while I've been on the lookout for LH <12 mm dia ball screws preferably with a ca 3 mm pitch w/o any success...
Q: Isn't the movement so darned smooth now, that the cross slide will move when turning due to the unbalanced improvised handwheel?

Keep up the good work and ATB

Johan

Quote:

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Originally Posted by DIYSwede

For a while I've been on the lookout for LH <12 mm dia ball screws preferably with a ca 3 mm pitch w/o any success...
Q: Isn't the movement so darned smooth now, that the cross slide will move when turning due to the unbalanced improvised handwheel?
Johan

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I have been unable to find a LH version also.
No, there is no problem with unwanted movements. The action is very smooth but not loose, there is enough friction from the dirt seals to prevent back driving and the unbalance from the handle is trivial in comparison.

<!-- BEGIN /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->
Thanks tonyfoale! We've added your Cross Slide Screw Conversion to our Lathe Accessories category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-cross-slide-screw-conversion"> <img src="/uploads/243474/homemade-cross-slide-screw-conversion.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-cross-slide-screw-conversion">Cross Slide Screw Conversion</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/lathe'>lathe</a>, <a href='https://www.homemadetools.net/tag/modification'>modification</a> </div> </div> </div> </div>
<!-- END /var/www/html/homemadetools/protected/modules/zeus/views/tool/postUpdate.php -->

Paul Compton pointed out in the Youtube comments that LH ball screws are rare because these screws are mainly used in CNC machines and it is simply a matter of software as to which way they turn. So there is no need to make both RH and LH screws.

That is a beautiful thing. You could drive a truck through the slop in my cross-slide. Hmmmm..........

Don't recall ever handling a cross slide equipped with a ball screw. Check that, just one, a Haas TL model. It runs Conversational CNC or manual using the built-in DRO. That handle was counterbalanced but still didn't feel as it would react to pressure and turn on it's own. When you let go, it stopped.

I'm certain elimination of backlash is part of that, with a common leadscrew subject to vibration, wear and imperfect mating surfaces.
It's also why climb milling [on ball screws] is OK, even by hand. We are so used to avoiding it, the sensations of touch, sound and vision can be unnerving.

I'll affirm rarity of LH ball screws, even in balancing mechanisms with 2 screws. Reversible motors and coding alleviate them.
The very best old [ie serious] heavy milling machines had anti-backlash mechanisms using 1 each. A few incorporated manual rapid traverse too, by choosing right or left handwheel. That expedited production, with an unloaded traverse motion not subject to feed rate.

Great work, Tony
McMaster-Carr has a few English LH ball screws/nuts; probably not useful over in Spain

But, I did find this company that has LH metric.. might be worth a look.

https://us.misumi-ec.com/vona2/mech/...0029090%3A%3Ac

McMaster-Carr? Not Amuzin, Kneebaye, Grunger, MshooshC or other inconsequential upstarts? Don't get me going on Asian marketers, that lose grip on your search terms.......like endmills and lipstick! What, at distance they look alike? :headscratch::brickwall::angry:
McMaster-Carr originated the concept of branched industrial warehousing, and ready supply lines. The others are, well just that, the others. There is even a thriving market for out of date MC catalogs, you don't get one without being a regular customer. The online version hands down exists as THE most easily navigated reference, especially when thousands upon thousands of categories [not mere items, lol] are described clearly.
I'm just a dedicated fan; not a stockholder!
But they respond w-o-r-l-d-w-i-d-e!

McMaster-Carr was our "go-to" source for many years in the tool & die business.
They were always, ALWAYS good on deliveries, and had most anything you could want.
Perishable tooling was usually bought from other companies that specialized in same.

Quote:

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Originally Posted by Toolmaker51

I'm certain elimination of backlash is part of that, with a common leadscrew subject to vibration, wear and imperfect mating surfaces.
It's also why climb milling [on ball screws] is OK, even by hand.

---

My mill had ball screws from new and I almost always use climb milling without problems. That is both manual and CNC.

Quote:

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Originally Posted by tonyfoale

Paul Compton pointed out in the Youtube comments that LH ball screws are rare because these screws are mainly used in CNC machines and it is simply a matter of software as to which way they turn. So there is no need to make both RH and LH screws.

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Umm, how'z about turning the ballscrew nut around. Then it'd run backwards! Same-o, same-o, right?:cool::smash:

Quote:

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Originally Posted by dagrizz

Umm, how'z about turning the ballscrew nut around. Then it'd run backwards! Same-o, same-o, right?:cool::smash:

---

I am at a loss to decide if this is a serious comment or not.

Its project is interesting, it is a pity that you will have to get used to the inverted advance of the cross slide (not that this is the end of the world). A search on a famous chinese sales website could have helped before the purchase...


Attachment 38267

Quote:

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Originally Posted by tonyfoale

I am at a loss to decide if this is a serious comment or not.

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Definitely not serious; I just couldn't resist... Actually, I'd consider this upgrade for my Taiwanese 12 x 36, especially if the LH ball screw was available.
[edit]
I just checked at Thompson; they list a 5/8"LH w/ 0.2 lead, 6' long [https://www.thomsonlinear.com/en/product/190-9099]
The nut [https://www.thomsonlinear.com/en/product/8106-448-037] needs a screw-on flange [https://www.thomsonlinear.com/en/product/8105-448-002]. You'd have to machine the shaft to fit, and I haven't researched the fixed & floating bearing options.

Quote:

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Originally Posted by machining 4 all

Its project is interesting, it is a pity that you will have to get used to the inverted advance of the cross slide (not that this is the end of the world). A search on a famous chinese sales website could have helped before the purchase...

---

I am getting used to it, slowly. The truth is that I never gave any thought to the hand of the thread, I just ordered a screw assembly. Since then I have searched for LH versions without success.

Quote:

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Originally Posted by dagrizz

I just checked at Thompson; they list a 5/8"LH w/ 0.2 lead, 6' long [https://www.thomsonlinear.com/en/product/190-9099]
The nut [https://www.thomsonlinear.com/en/product/8106-448-037] needs a screw-on flange [https://www.thomsonlinear.com/en/product/8105-448-002]. You'd have to machine the shaft to fit, and I haven't researched the fixed & floating bearing options.

---

Many thanks for that. BTW your links returned "product not found" responses but if I copied and pasted the PNs from your links in their search box it had no problem finding them. The screw on nut mounting is like I have on the Z axis of my mill, it would have been much easier to fit on the lathe than the flanged nut that I got.

Mariano found some LH versions of the same size on Aliexpress. I'll order one. here is the link for anyone else who is interested.

https://www.aliexpress.com/item/1005...archweb201603_

...the sizes being 16 & 20 mm diameter?
sometimes hard to understand Chinese specs

Quote:

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Originally Posted by gatz

...the sizes being 16 & 20 mm diameter?
sometimes hard to understand Chinese specs

---

1605 and 2005 seem to be fairly standard specifications from what I have seen. !6 or 20 mm as you surmise, both with 5 mm pitch.

Congratulations tonyfoale - your Cross Slide Screw Conversion is the Homemade Tool of the Week!

This is a unique and well-explained modification, and your second Homemade Tool of the Week win in a row. Nobody has ever won three Homemade Tool of the Week awards in a row. Previous two-in-a-row winners are:

Brendon in 2015: Marking Gauge and Dovetailing Bench
mklotz in 2016: Bench Block Enhancements and Model Cement Mixer
tonyfoale in 2016: Horizontal Milling Machine and Drum Brake Grinder
rossbotics in 2017: Tilting Dividing Fixture and Dial Indicator Attachment, and again for Center Punch Guide and Deburrer
thehomeengineer in 2018: Ring Roller and Axle Stands
Stevohdee in 2018: Milling Machine Power Feed and Tool Post Grinder
Mark Presling in 2019: Demagnetizer and Quick Change Indicator Holder

Some more nice builds from this week:

Shear Tool by olderdan
Radius Turning Attachment by ttmrj
Rose Index Block by N4NV
Mill Spindle Plans by engineer steve
Mill Riser Block by tmate3
Clamp by orioncons36
Shear Tool by DIYSwede
Paint Removal Method by HandmadeCreativeChannel
Dial Indicator by machining 4 all
Spring Fuller by Philip Davies
Log Splitter Engine Replacement by IntheGroove
Gerson Hammer by IntheGroove
Drill Press Drill Bit Adaptor by HandmadeCreativeChannel
Wood Burning Stove and Heater by Mr.DK DIY
Gas Cylinder Wrench by Don42
Industrial Jointer Mobile Base by tiger carpenter


tonyfoale - we've added your tool entry to our All Homemade Tool of the Week winners post. And, you'll be receiving a $25 online gift card, in your choice of Amazon, PayPal, or bitcoin. Please PM me your current email address and gift card choice and I'll get it sent over right away.


This is your 12th Homemade Tool of the Week win! Here are all of your winning tools:

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did you get the LH screw from Aliexpress ?

Quote:

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Originally Posted by gatz

did you get the LH screw from Aliexpress ?

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Yes, eventually. That purchase turned out to be a non-pleasant experience.

Firstly, I was hit for local tax and customs duty which doubled the overall price. TNT entered a price which was hiked up so the tax was more that it should have been. Since then I have heard that stuff shipped with TNT is more likely to have this problem. Of course they act as the customs agent and charge an additional fee. My thoughts did run to wondering whether this was a nice little earner for TNT.

Secondly, the screw does not appear to be of the same quality as the RH screw which I had fitted previously. The surfaces of the nut were ground much rougher and the action was not very smooth. I decided not to risk fitting it. It resides on the shelf in its shipping box.

That finally convinced me that the best solution was to motorise the fitted screw and drive it with an MPG in manual mode and have a powered mode which would maintain constant surface speed when facing (within the range of speeds of the VFD/motor combination). To that end I bought a closed loop stepper motor and tested a bread board lash up. That worked so well that i decided to fit a ball screw to the Z axis as well. Of course that has to be motorised because ball screws do not come with half nuts. You cannot easily disconnect the feed for manual. Anyway as of today I am waiting for that ball screw to arrive, it should have been here nearly 2 weeks ago. Not knowing what torque would be necessary to drive the screw under the hardest conditions I got a large closed loop NEMA34 motor. Almost certainly overkill.

When this is complete the lathe will be fitted with all the hardware and motor drivers necessary to be a CNC lathe. I do not want a CNC lathe. Every time that I want to turn a simple bush or similar I do not want to wait for a computer to boot up and nor do I want to have to write some G-code or do a drawing to make a simple part. I almost never make drawings. I have analysed what I want a lathe to do and it comes down to:
1. Simple turning and boring.
2. As 1. but with tapers.
3. Facing - preferably with near constant cutting speed.
4. External and internal threading.
5. Ball turning.

I have no need to make fancy chess pieces nor other fancy shapes.
Many people make ELS (electronic lead screw) conversions but most are Z axis only and so will only be capable of 1. and 4. above. Having motors on both Z and X axes allows for all the needs above and the control is still pretty simple. A few calculations of the computing requirements showed that the maximum pulse rate from an Arduino would be inadequate for high feeds at high spindle speeds so I have opted for an ESP32 to handle the smarts. Many times faster than an Arduino and dual core. The two cores allow the motor signals and operator input to be separated.
I have the software written and I am just waiting for the Z screw to get it done.

This started out to be a single sentence reply, but like the lathe itself it has been subject to mission creep.

Understand the frustration.
it's often good to put it into words to overcome that frustration.

Quote:

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Originally Posted by tonyfoale

This started out to be a single sentence reply, but like the lathe itself it has been subject to mission creep.

---

Thanks, Tony for that line!
This absolutely encapsulates that feeling of mine, when finding myself in a project that already has sunk a pretty bundle,
soaked up even more man-hours and still (or just because of that) looks farther from (possible) completion than ever.
Then its high time to escalate the commitment!:)

Cheers
Johan

Quote:

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Originally Posted by DIYSwede

.......... and still (or just because of that) looks farther from (possible) completion than ever.
Then its high time to escalate the commitment!:)

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This is not far from completion, I know that ELS projects are supposed to take months or years in some cases but that will not be the case with this project. It has been a bit stop/start because of lead time on some bits but once I have everything I expect to finish it within a few days. Raising commitment is neither required nor possible.

Preparing a post for this forum on the work will probably take longer than doing it.

Tony: My post was entirely intended to be of the "self-reflective" kind,
in no way implying you would be suffering from my particular shortcomings.

I for one, am eagerly awaiting further posts on your cross slide mods.

Cheers & keep up the good work!

Johan (assuming I really should postpone my project procrastination)

Quote:

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Originally Posted by DIYSwede

Johan (assuming I really should postpone my project procrastination)

---

Good Sir; aha; good to know more than one of us expends effort that way, postponing procrastination. Looking for some tidbit to ally this link-wise, found that procrastination not exclusively a negative trait.
Now, what was I doing?

Quote:

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Originally Posted by DIYSwede

Tony: My post was entirely intended to be of the "self-reflective" kind,
in no way implying you would be suffering from my particular shortcomings.

---

I understood that, I was just having a bit of fun with it.