Thread: ELS Electronic Lead Screw

Hello all

As some of the regular readers may know I am looking at upgrading my lathe. My lovely wife asked why I needed a knew lathe and what is wrong with the one I have. Of course I gave a long winded reply to make it sound like I would be made not to get a new lathe. I don't think it worked but she would not object within reason. No I wont be buying a new Monarch lathe.

To be perfectly honest I can easily overlook a lot of extra's I would like but what I really dislike about my current lathe is to cut threads I need to change the change gears and to set feed I need to change the change gears. What I want in a lathe is a full thread norton style gearbox and separate feed selection.

It occurred to me that an Electronic Lead Screw (ELS) would solve the problem. I have read the complete post about the Clough42 ELS conversion. For various reasons I am time poor, limited in motivation at times and have to many projects lined up. I know I would not get around to making and installing the Clough42.

Has anyone a recommendation for an ELS that is a reasonably quick install, say can be done in a day and is reasonable price. I don't need full CNC integration.

Thanks Steve

This is the way to go on a budget: Electronic Lead Screw Main Page (I have one)
This if budget is not so critical: https://www.rocketronics.de/en/els/
Clough 42 ELS if you want to reinvent the wheel....

Joe

The first one looks exactly like what I need. I will have to do some reading but at first glance it may be the way I go.

If I buy the assembled kit how long do you recon it would take to add this kit to a 11 X 24" Chinese lathe?

It also looks like the assembled kit and a few extras should be able to be landed at my house for about $400 AUD depending on postage and exchange rates.

Steve

There are some videos on the ELS4 controller posted on youtube - here's one - https://www.youtube.com/c/JohnSL/videos - scroll through his videos and you'll find a series on fitting the ELS4 - worth a watch to see what is required to fit it.

Originally Posted by Reidy41

Joe

If I buy the assembled kit how long do you recon it would take to add this kit to a 11 X 24" Chinese lathe?
Steve

That depends entirely on your skills and ingenuity. That will b e true for every kind of ELS you get. Designing a way to mount the stepper or servo motors to the two axes, figuring out the motor sizes needed and the reduction (if needed) is the first part before you do anything.
Best starting point would be to put an average size work piece in the chuck, start entirely manually turning at the average depth of cut and feed speed.
Stop the lathe and get a spring balance or electronic scale (like a luggage scale) and hook that onto the hand wheel. Then start turning again, using the scale to pull the hand wheel around. Read the forces required to do that. Now measure the radius of the hand wheel at the centreline of the handle. Using that information, convert your numbers into inch-pound or Newton-meters. Now you know what the torque required by the saddle motor.
Next do some facing, exactly the same way. That's the torque required by the cross-feed motor.
To get that torque, you can either get motors with that torque and mount them directly on the leadscrews. Alternatively for example if you need to use a toothed belt to drive the screws conveniently, you have the freedom to change the ratios. E.g. if you choose a motor with half the required torque, you can use a 1:2 belt drive ratio to get the required torque. The price is half the speed - nothing is free
Have a good look at your lathe, check out as many conversions as you can find (including the many many CNC conversions) on a lathe like yours and find a suitable design that YOU can build or adapt to your means and skills.
AFTER that, start looking at the speed sensing needed for an ELS and how you can adapt a mounting to your lathe.
One other consideration is backlash from your leadscrew and crossfeed screw: when you control these electronically, this comes into play. The motors get told how far to turn in degrees or steps, but there is no feedback whether this has just taken up the backlash or has actually moved the saddle or cross slide! The ELS can be told how much backlash to expect and will add that in degrees or steps to the motor command. However, many leadscrews aren't accurate enough for that backlash to be uniform over the length of their threads.
So, many people change the acme or trapezoidal screws to ball screws. That can remove the backlash entirely, using preloaded bearings to contain the screws longitudinally. Doing this helps a lot, and still allows hand wheel operation, but be aware that the pitch of ballscrews is likely to be coarser than the originals. Lastly, ball screws can 'backfeed'. That means unlike acme or trapezoidal screws, they won't stay still with forces applied to the ball nuts axially. That force will SPIN the screw! So for manual turning, you will have to either hang on to the hand wheels or lock the axis....
The electronics and electrical connections are relatively simple.
Good luck for your build!