Electronic Leadscrew Torque Test

[@misterfixit1952]

BTW, I just read your bio, on your youtube page. As a former Mechanical engineering Tech, I am envious of your career with Sandia Labs. You have participated in many of the engineering milestones of my life. Way Kool, it must have been an exciting time.

[@jonrbryan]

I got to work with a lot of great people (with only one or two exceptions). I was in groups that worked on a lot of boondoggles, too. It was always interesting, though. Some of it so "interesting" that I had to sign my life away for 70 years.

[@misterfixit1952]

@@jonrbryan I guess I'll have to read your posthumous memoirs to find about that alien tech ;-)

[@misterfixit1952]

If your ELS project were open-sourced, more people could participate in improvements and forks. This could greatly facilitate moving toward my dream of an integrated ELS-DRO with a unified interface with end-stop/reversing capability. This is the ultimate goal of mine, the perfect manual programmed, semi CNC lathe. Being able to manually program simple procedures, using a touch screen, with the precision of a DRO and ease of an ELS would make the ultimate maker lathe. Based on my knowledge of Yuriy's touch DRO and your ELS, the two could be easily (?) integrated into a unified product that could be assembled and installed on almost any lathe for less than $300. This would greatly increase the utility and precision of any size lathe, allowing just about anyone with reasonable skills to produce amazingly precise work with reasonably priced equipment. I can also imagine a fork that adds a cross slide stepper, enabling any lathe to easily do tapers and more complex, standard shapes like ball ends, without having to go full out CNC. A CNC lathe requires CNC programming on a computer, a dedicated CNC lathe, and you lose the ability to easily do manual work. Doing standard, but complicated procedures, like threading, tapers, and ball ends from a touch screen menu, with adjustable parameters, would be the perfect in-between capability. With opensource programming capability, I envision user-created, addon pages (libraries) with new capabilities. Whether this could be accomplished using an Android tablet, like Touch DRO, or add-on libraries to a dedicated touch screen (like yours), remains to be worked out. An Android tablet is the perfect interface for the front end of a user interface because it is easily updated and the touch screen is the perfect input interface. Also, they are becomingly increasingly more powerful at declining prices. Also, the Bluetooth interface is adequate for, noncritical, communications with a controller and wi-fi access to the internet makes access to libraries and updates an easy matter. Currently, Touch DRO only moves information one way, from the controller, using Bluetooth, to the interface (the Android tablet) What I don't know is if an Android tablet, using Bluetooth, is reliable enough to do the real-time control of the machining process. I have my doubts due to the often quirkiness of Bluetooth. Maybe a hardwired USB connection would work better. Control is probably best done using a separate processor at the controller board, receiving parameters from the Android. Instructions, in the form of Gcode, calculated axis movement or library values must move from the interface to the controller. Anyway, this subject just gets more complicated, the more I think about it and this thread could go on and on. The bottom line is an opensource project could address all of these questions and (more quickly) come up with solutions. I think I will shop this concept around on some of the machinist/CNC blogs and see what kind of interest I can stir up. I am just sorry that I don't have the required skills to take the lead on a project of this magnitude. I guess I'm more of an idea kind of guy. I see this idea becoming the 3D printer (hardware) concept translated to the machining community with a GRBL type board and a Marlin type control program.

[@SouthernEngineering]

Thanks for the info. I just purchased a Clausing 4912 from a school auction; it's in great shape, but I plan to use an ELS when I start the rebuild; choosing between your project, and Clough42 design will be difficult. P.s. I have a couple of bending beam torque wrenches, they have proven invaluable over the years. Keep up the excellent work. See you on YT 😁

[@jonrbryan]

Those are interesting machines. I hope you got a good deal. I assume that you're going to drive it from the tail end with the gearbox in neutral?

[@SouthernEngineering]

From what I understand, the Clausing is a good lathe, and their factory is 15 min away. I won the bid just over $400, you can see a comparable lathe on eBay for 2 to 3 K, so I'm a happy guy. The plan is to freshen up the lathe and get to know it a little better then add the ELS (undecided on which end), so I can go metric and back with just a couple of buttons.Right now I'm getting my shop finished for the winter, and then watch out, I've got major projects in the works.

[@jonrbryan]

@@SouthernEngineering That sounds like you got a great deal. Congratulations, and may it serve you well. One of my objectives with my ELS was to be able to return the lathe to original condition. I'm looking at pictures of your Clausing model and I think you'll have to drive from the tail end to accomplish the same. You might want to go with a short NEMA34 motor on a lathe that size, and you would have the room on the tail end. You would just have to extend the leadscrew. I've got a detached shop planned but I just couldn't get it done this year.

[@jasonruch3529]

I would leave it be since its already a GREAT geared lathe....the els is geared for us guys who need the physically change gears in my opinion....sell me the lathe and ill give you my logan 200 if ypu want a els that bad. 😂

[@misterfixit1952]

I was planning on using a 3N-M stepper for my lead screw stepper. I think that's about the largest NEMA 23 you can easily get. Also, they are only about $35 on eBay. The other alternative is to use one of the stepper/servo hybrids and those are about $100-120, getting a bit out of my price range. Based on your test, I think that a 3N-M (425in-lbs) should do the trick with a 5 to 1 ratio on the belt.

[@jonrbryan]

I haven't been able to find anything larger than 2.2Nm that will fit where I have to put it, and most of those have an encoder that adds too much length. I believe a ClearPath SDSK rated for 3.5Nm would fit, but it's $300.

[@rickhaass1133]

I wondered if that would be an issue. Thanks for testing it. Have you been following Clough42's electronic leadscrew project?

[@jonrbryan]

Yes, he's working much harder at it than I am, which is reflected in the number of subscribers that he has. My approach to the user interface is much different. I like my touch screen and knob. I'm also enjoying retirement, and am not strongly motivated to support an actual product. I think I'll publish the code and schematics at some point, but I don't feel like starting a business.

[@rickhaass1133]

I like your UI, it’s done pretty well. I still wonder why the manufacturers haven’t done this yet.

[@jonrbryan]

@@rickhaass1133 Only "pretty" well :)? There's a gulf between a programmable gearbox and a full-up CNC. I think each has its place, but I imagine that they've done a market analysis and concluded that there just isn't enough money in it. But it seemed to take a long time before they started selling machines with VFD's, so it might happen eventually.

[@rickhaass1133]

Put it this way, I like it better than the other. It’s pretty cool.

[@apollorobb]

@@jonrbryan I would love to have the code for this to play with it a bit and try it with a Servo

[@misterfixit1952]

Do you have an idea of the required torque that you need to move your leed screw during a worst-case scenario? I imagine that a deep cut on an 8 TPI thread would do it. Were you making a new backing plate for a chuck? I have some barbell cast-iron weights that I want to turn into backer plates and I will need to cut 8TPI inside threads for my 9x20 lathe.

[@jonrbryan]

I'm going to find out. The torque limiting is sort of a "feature", since it should keep me from breaking things in the event of a crash. Just a few weeks after getting the lathe I broke the miter gear mount in the apron by losing track and power feeding the cross feed to the front limit of travel in a low gear. I said that I could go up to 8:1, but actually that's 10:1, so I could double what I have now. From there I would have to switch to a ClearPath servo, which has twice the torque (and three times the expense). I was cutting a 3/4"-8 Acme to use as a plug gage for rebuilding some half nuts.

[@misterfixit1952]

@@jonrbryan Yeah, at the bottom of an acme thread, the cutter is almost like a parting tool and can easily cut on two faces and drag on the third. With threads, it's not as easy to take light passes although, with your ELS and a fixed stop switch, you could reverse the feed, back out and take light cuts a lot easier. That's one of the best features of your ELS scheme. It always kind of weirds me out, cutting into a shoulder and having to suddenly stop. the feed. Having a DRO capable ELS is my idea of heaven.

[@jonrbryan]

Down the rabbit hole I go. I'm trying to score a force gauge and actually measure it. Rough T = KDP calculation gives me a number between 550 and 1100 pounds of force applied to the carriage depending on the friction loss. I can tell you that even before I geared it down I could push on it my hardest without slowing it down, and I weigh about 270, so I'm inclined to believe the rough calculation. Gives you an appreciation for the kind of cutting forces that are involved when cutting an 8tpi thread.

[@misterfixit1952]

Do you have enough room to use a short NEMA 34

[@jonrbryan]

Ooh, I just mentioned a NEMA34 motor to Southern Engineering for his "new" Clausing a few seconds ago. No, the NEMA23 that I'm using just barely squeezes in.