Dark Art CNC Part 3 - Leadshine Servo Motor Install and Tuning

[@DavidR8]

So impressed with your design and execution David!

[@masterchief4125]

Awesome stuff as always dude! Well done

[@nitacawo]

congrats, that spindle is a dream and overall machine is great. Jealous :)

[@jeanbaptistemotsch8296]

Aux top vraiment géniale un vrais passionnés fait plaisirs a voir encore merci

[@GGGG_3333]

Glad to see you back. When did the channel name change? Does that mean it will be about guitars from now on?

[@DarkArtGuitars]

I changed the name at the beginning of the year. It'll be a mix of guitar builds as well as stuff like this that helps me build guitars.

[@GGGG_3333]

@DarkArtGuitars just saw that video. I was wondering where you went, since I didn't get any update from your channel for almost a year or so 😅. I am here either way, I can't wait to learn more from you, whether it's CNC or guitar related or anything else 😁. I just received my CNC and can't wait to start tinkering with it. Maybe even build me a guitar one day 😁. Thank you for sharing your knowledge and passion with us 🙏.

[@johnbubu8310]

Well done!

[@bobweiram6321]

Celebrimbor is building a new forge to make the one axe to rule them all.

[@n4eanm]

Roughly how much does one of these CNC's cost? Thanks

[@DarkArtGuitars]

I'll do a breakdown in the final video, but I think it's around 12k as I have it configured. But you could also get away with less by choosing a cheaper spindle.

[@kenrobertson8239]

For the Y motors, one thing I've seen done that worked well is to figure out the weight of your gantry and endcaps, then add the equivalent amount of weight onto the X motor, then run the tuning on the X motor, export it, and apply it to the Y motors. Backup your original X values first though.

[@DarkArtGuitars]

Yes, either that or reducing the weight and disengaging one of the two Y drives. I went with the latter, but both are hacky workarounds at best. They should just allow you to connect to both drives and tune them at the same time since this isn't exactly a niche application.

[@scratchbuiltdesigns]

I tuned my Delta servos on a tandem servos axis lately. It is in fact relatively easy. You do this, without certain elements on the gantry, so that the total weight represents roughly 60% of the total weight. In my case it was tuned without the Z-axis installed. Then you decouple the ball screw on the slave side and tune the servo on the master side. Your gantry needs to have a certain rigidity for this, but I believe your machine is rigid enough. The parameters are then copied to the slave servo - done. I made a detailed post on Insta early October with more details of the process. Since your spindle is back at Spinogy anyway, taking off the Z-axis for tuning might be still an option for you. Can your tuning software calculate the parameters based on a given stiffness value? If so, you can gradually increase the stiffness value of the auto tune and have the other parameters calculated accordingly. Then run the machine and see how it feels. Go higher with the stiffness value until it feels uncomfortable and back up to the last one, which was good. This should reduce your position deviation greatly. If your tuning software doesn't have that feature, try to increase the velocity loop gain manually. This parameter has the biggest influence on the position deviation.

[@DarkArtGuitars]

Thanks for the idea, while an approximation it's probably about the best that's possible with this setup and auto tuning. From what I understand the stiffness is one of the parameters that is varied during the tuning, but I might be wrong. What am I looking for with a too low/too high stiffness value? Like in what sense uncomfortable?

[@scratchbuiltdesigns]

@@DarkArtGuitars Uncomfortable is when the servo starts to shake and vibrate after you press "servo on". Or when it makes loud noises during the run. Then it is too stiff. When the stiffness is too low it runs quiet and smoothly, but then it overshoots its end position and the position error is way to high. I tuned mine to a position follow error of 6-7 microns. But my servos run at 5000 steps/rev on a 5mm pitch ball screw, which certainly helps. Tuning only one side with 60% load is what most people do who run a tandem axis with servos 👍

[@scratchbuiltdesigns]

@@DarkArtGuitars One more thing I have noticed. You tuned at 3000rpm. That is likely your G0, but not your average milling feed. When you try to improve the position following error manually, it is better to do it at an rpm which corresponds to your normal milling feed (like 5m/min, or something) Because the position following error during a G0 repositioning move is not really important, as long as the end position is correct.

[@DarkArtGuitars]

@@scratchbuiltdesigns Thanks for the info! The auto tuning did various speeds up to a max of what you put in, hence I put 3k rpm.

[@johanedvardsson835]

Nice machine you got. You could run it at 4000-8000mm/min with no problem in wood, to not burn your cabide tools and get big chips. Maybe 6,8mm Carbide End mills.

[@DarkArtGuitars]

For sure, that's why I went with servos instead of steppers.

[@josepatron4950]

Wow very impressive. I was excited hoping to see if somehow you came up with a great idea for a tuning method for the Y axis. As cost effective and amazing these servo kits are, what always keeps me from using these servos on dual motor gantry machines is there is really no way to properly tune the motors on Y. There is a video on youtube from caugh51 that shows him doing it on an avid build, but sheesh.... impressive indeed but not very intuitive, using weights on the X axis to simulate the total weight of the gantry. I wish the manufacturers of theses servo kits would devise a system similar to the single axis tuning that works with two amps. I know I'm reaching for the stars but one can dream.... right? I hope you are able to do this and share how you went about it. I really love your videos on the machines, they are right up my ally!!!! Thanks!!!!!

[@fearlyenrage]

Woni dr M-Budget Brennsprit gseh ha hetz mr dämmered... Muess e Schhwizer sii ^^ Schöni Gittare machsch! =)

[@DarkArtGuitars]

Merci

[@fearlyenrage]

@DarkArtGuitars bitte gern.

[@droneforfun5384]

Hi! On another Leadshine video some guys mentioned that Leadshine support was not good - long wait for replies, and short answers. I know this is a sponsored video, but did you actually try the Leadshine support for troubleshooting? Did you investigate for alternatives to Leadshine? And big thanks for the nice video, great machine 👍

[@DarkArtGuitars]

I was in contact with their support, but that was initiated through my contact so not representative of what you would get. There are many other servo brands out there, but it seems like Leadshine strikes a good balance between having the software with all the features to tune them properly (and in English) while still being reasonably priced. You can get cheaper servos on Ali but there the software is doggy, or there are brands like Clearpath that will be even better but also much more expensive. Otherwise if you want a cheap closed loop system I'd go for closed loop steppers, they are much cheaper and don't need tuning but are still much better than just regular steppers.

[@droneforfun5384]

@ thank you. I hope you find a solution to the auto tuning for dual Y motors, which seems to be a lacking feature in the leadshine software.

[@DarkArtGuitars]

@@droneforfun5384 The "solution" is just to tune one of the motors with the other one disengaged and the gantry made lighter to compensate. It's a hack but gets you somewhat close. I understand the timing to synchronize the two drives for tuning is too tight to work over USB, so the drives would have to be connected to each other directly. On their higher end models this is supported but not for this one. I suppose there is little they can do.

[@droneforfun5384]

@@DarkArtGuitars ok so you mean it is not possible to square the gantry via masso during normal operation? Or just for the tuning.

[@DarkArtGuitars]

@@droneforfun5384 just for tuning