LinuxCNC as ELS for lathe?

Rather than a full cnc conversion of my Colchester Bantan I'd like to try a Electronic lead screw conversion, possibly as a first step to full cnc.  Ive mounted a belt driven rotary encoder to the spindle and have an RPI4 and 7i96 (ethernet).  Is there an easily configurable way of using linuxcnc for this Or? Or am I best off building something bespoke with a microcontroller (based on clough42's ELS or similar)?

Tommy,

An electronic lead screw is just that - it's a normal manual lathe leadscrew, coupled to the carriage with a standard half-nut.  The difference is that instead of being locked to the spindle through a set of change gears or a q/c box, it's driven by a servo or stepper.

There is no motor or anything else coupled to the top slide or compound.  Those are still fully manual.

The "electronic" part is three components - a spindle encoder, a microcontroller, and a servo/stepper drive.  The controller takes the spindle encoder pulses and converts them to a S&D signal the (new) leadscrew motor.

The magic trick is a simple user interface which permits you to select a particular electronic gear ratio between the spindle and leadscrew.

For a grown-up industrial (or serious hobby) lathe with a q/c gearbox that has both a leadscrew as well as a shaft-driven power feed, an ELS is generally a waste of time.

However, for small hobby lathes which are typically driven only by a leadscrew and may still have individual change-gears, an ELS is a godsend.  Imagine having to switch out gears just to go from a roughing to finishing chipload?  Very time consuming and annoying.

Further, these lathes usually require an even more lengthy swap between metric and imperial feeds for threading.  What if you're missing a gear - how do you cut a particular thread?

Depending on the complexity of the microcontroller software you may even be able to set a feed-per-rev rather than a specific ratio - the ELS does the math for you.  Just program it (usually a simplistic GUI or dedicated buttons), engage the half nuts, and away you go.

In addition, a true servo may be able to stop (or reduce) crashes if there is a torque overload sensor.

On one hand, you could ask what's the point? Why not just CNC the thing?  The answer is - no significant hardware changes, very low cost (compared to a full X/Z retrofit with ballscrews), and very easy interface.  No new 'language' to learn, no program to write.

If all you have is a small lathe that is annoying to use, an ELS can be a game-changer.

I think LinuxCNC is way overkill if you just want ELS functionality and would probably be more work than building a dedicated ELS. But I am sure it could be done. I built the Clough42 ELS for my 8x12 Lathe just so I could eliminate the change gears. It works great.

Exactly as Spumco says. My Bantam is Metric and has what I'd say is a very good threading gearbox, for metric threads. Unfortunately a seem to cut almost as many Imperial threads as metric, including Whitworth (and the odball 12tpi for 1/2"), at which point changing the change wheels is a pain (accepting that everything is relative). I will ultimately do the full CNC conversion, which is why i have a 2nd 7i96 (my first being on my mill).

Based on the responses above it sounds like there's no simple way of using Linuxcnc for this purpose?

I'm not an expert by any stretch in LCNC, but I can think of a couple ways of using LCNC for this.  But a dedicated ELS is likely simpler, assuming you can borrow someone else's design and microcontroller program.

And creating a user interface for LCNC will be a challenge if you've never done a GUI before.

Considering the only difference between doing an ELS and full CNC control in Linuxcnc is one stepmotor. What's the point of only doing it half way?

Perhaps someone simply wants a manual lathe and not a CNC lathe, but they want the ability to cut many different threads or feed-rates.

I think of them as enhancing a manual lathe rather than being a half-a$$ CNC lathe.  Like a power down-feed on a mill quill - not necessary, but makes a huge difference in user experience.

Just because you add cnc capability doesn't mean it has to loose the ability to be used manually.

I certainly would want to keep manual capabilities on a lathe, if I were ever to convert one.