NEMA selection for electronic leadscrew

[John HinkleyParticipant @johnhinkley26699]

With the original question having been posted over five years ago, I’m not sure that you’ll get a response from Kevin. For what it’s worth, I have converted two lathes to ELS, using two different control systems. Each installation is highly satisfactory and in both cases I used closed-loop NEMA23 frame stepper motors with 3Nm holding torque and 2:1 reduction between the steppers and the leadscrew.

For the larger, a 9×20 Asian generic lathe I followed the Clough42 route but for the lately acquired 7×14 mini lathe, when the Clough system was no longer exported to the UK, I used the single-axis control unit from electronicleadscrew.eu.  Both have extensive footage on YouTube and I’ve put my efforts on there, too.

John

 

 

[Robert Atkinson 2Participant @robertatkinson2]

Hi John,

As a user of both, how doe the Clough42 and ElectronicleadscrewEU designs compare from a users point of view?

Thanks,

Robert.

[John HinkleyParticipant @johnhinkley26699]

Robert,

My opinion is that the Clough system is a robust, well thought-out arrangement which is almost a one-touch solution when threading or selecting feeds and can be enhanced by a home programmer (not me!) to give additional or one-off threads due to its open source software.  The downside for me was the Texas Instruments processor unit, £50 a pop when I bought it and thus expensive when you have to replace it as I did, by somehow frying it!  The Electronicleadscrew item is cheaper, just as effective and has the advantage of semi-automatic threading.  I think it’s less aesthetically pleasing than the Clough unit, due to the connections being located on the top of the console.  I overcame this to a certain extent by redesigning the front cover to hide them from view, 3D printing it out in matching black filament.

Next time, I’d go for the 2-axis version for very little more money and an incentive to motorise the cross slide to fully automate the threading process as well as other enhancements such as taper turning etc.

John

Edit.  When last I checked James Clough was not exporting his kits or individual items to the UK.

[david childParticipant @davidchild69586]

Thanks for your reply John, Can you check my logic here?

You used a 3Nm motor with 2:1 gearing that gives 6Nm at the leadscrew. My lathe is 13″x48″, so guess I’d need (12/9)x(48/20)=14.4Nm.

My concern is that with a 2:1 gearbox the motor will be operating at a higher speed and hence lower torque. This would show when turning coarse threads. Is this an issue with your setup?

[John HinkleyParticipant @johnhinkley26699]

David,

I regret that I’m not qualified to give you a definitive answer to your query. However, I will say that, on a suck-it-and-see basis that I would go for a beefier motor in, say, a NEMA34 frame with that sort of size lathe.  Have a look at the data sheets for the steppers that you are considering and see what the torque curve is like. James Clough did a video on motor selection/torque figures on his web site. I suppose it rather depends on thread type, pitch and depth of cut that you are intending to use.  Also, note that like most others, my drives are coupled to the lead screw with timing pulleys and belts.  No gearboxes were harmed in the implementation of the ELS to either lathe.  The electronicleadscrew.eu system allows for a highly customisable setup of the ratios of the various motors/lead screws.

John

Edit: Just realised that I didn’t answer your last question. No, I haven’t encountered any problems such as you suggest, but then I don’t try to cut anything more than standard metric threads up to 10mm only.

 

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