MKS SERVO42C Closed-Loop Stepper: Tests vs Servo with Field-Oriented Control and TMC2209 Open-Loop

The MKS SERVO42C closed-loop stepper system can be found at a reasonable price, but how does it stack up against open-loop steppers we know and love, and how does it perform compared against a servo system?

In this video, we put all three motion systems to the test. We look at the power and thermal performance, and run stress tests to find the maximum accelerations and speeds in a linear motion setup.

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Stepper stresser script repository:

Chapters:
00:00 Introduction
00:22 Setup
01:00 Contenders
02:15 Thermal Test
03:04 Test Setup
04:20 Test Procedure
05:17 Open-Loop Stepper
07:37 Servo
10:39 Closed-Loop Stepper
13:35 Drag Race
13:56 Conclusion

[CB_agotchi]

Would love to see more about your own servo design!

[mberoakoko]

This is not only amazing, but also informational.

[supergiantbubbles]

I appreciate how thorough you are in your documentation. Your presentation is really good too. Thanks :)

[xyzspec]

I struggle to install steppers, bro builds his own servo!
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[luneclips]

For stepper motor, acceleration and max speed are affected by voltage. That's why most of 3d printer use 24v, rather than 12v. Hope to see tests at 24v later as you get replacement.

[MattThePrintingNerd]

Awesome video Bo, looking forward to see more content about motors & servos!

[brettturnage]

You stopped me in my tracks! I am currently doing a klipper install on an older machine that has the S42B from BTT which has the same acceleration of 1000rpm. I’m going to swap those out for TMC2209 if I want to have the speeds that I’m hoping to achieve. Glad I stumbled upon this video.

[PhG]

Very impressive! I like your servo model very much! Btw, I have a facination for motors too, so I understand your devotion very well!

[ebrewste]

@8:40, an objective measure for the motor not being able to keep is seeing the current clip at the limit set in your drive. You don’t need to interpret the overshoot to say it is out of current. Great video!!

[prymaxxgaming]

Very good testing and real comparison
You deserve so much more views and abos with your quality

[SeaTaj]

Great video mate! I was tempted to buy some of these closed loop steppers. I'm glad I didnt!

[OMGWTFBBQSHEEP]

You should really make a video on that amazing servo of yours! Even though if you arent fully satisfied with it yet:D

[vietle-frrj]

people seem to really like your servo, hope it gets the noise removed and published soon 🤩🤩

[lukasnick]

great video. Your testing setup is amazing and I found the video very interesting to watch
since I am working on open loop steppermotors right now myself:)

[zachbrown]

do you have documentation on your servo design? would love to see more about it.

[Lucas-pjns]

cool video, would love to hear more about how you designed your servo

[thetooth]

I also had countless issues with MKS servos, I think the uC code for the serial interface is broken, with step and direction you can use much higher speeds, but once you overshoot the error window the motor will actually slow down to 100rpm and never catch up. It's also not capable of NPN/PNP (i forget which one was broken), the schematic and documentation suggests that it'll work in either direction but the actual implementation doesn't work, all you get is a big self induced oscillation loop. Anyway for my project I ended up switching to delta AC servos, several orders of magnitude more money but man the performance is scary good 👀

[JonnyWaldes]

Very interesting. I often buy some small components on Aliexpress that I don't have a use for, but might use someday on a project.

[BrianVoelker]

Really awesome to see. I come from the 3d printer world so seeing this type of stuff is fascinating to me!

[squishysquare]

I wish this was something that could be added to klipper, I think it could be very useful for finding max acc and speed with any given printer :D
I'd love to see this turned into a macro