MKS Servo42 Close Loop Motor (MAKERBASE) - Tests & Results 

Hi, thank you for your comment.

This is really helpful ! looking at the "genuine" now.

where can I find the legit? I am currently in the process of building my first diy 3d printer

I know this is 2 years old but... How is anyone producing an open source project and crediting the original creator of it, ripping it off? It's literally on the Github page for their MKS Servo 42. I'll give it to you if they only gave credits recently tho (the time on the github files do show 2 years ago tho). Dunno how well the MKS version handles errors, but the Bigtreetech one I have on X and Y have no problems whatsoever on noise on the cables, they're not shielded as well and X cabling runs along all my other cabling on the gantry, including the ABL servo, fan PWM and 40w heater.

​@@Kalvinjjyea other guy thinks he's on some high horse cause he isn't buying the "clone." Exactly as you say it's open source and using the term "clone" as if signifying its a negative thing is completely false and does not in any way mean it is a negative. Way more often then not clones are improved and better than the first iteration. This guy has some superiority complex syndrome or something

You really have no idea what your talking about

Thanks :)

Have you come to any conclusions about the questions you asked and concerns you had? Very interested to hear what you have to share about this topic

Are you running your TMC drivers in StealthChop or SpreadCycle mode? SpreadCycle gives more torque at the expense of some noise, faster moves, higher loads and some bigger motors (my NEMA 23s for example) will barely run at all in StealthChop anyway.

Hi Ron, you are correct. Regarding the installation on boards without replaceable drivers, the board needs to have driver headers. We now see boards that have them but there are lots of boards that don't have and the installation on those it's more tricky.

The "special" driver plugs into the board just as any regular tmc stepper driver plugs into

Hi, thanks for sharing this. I didn't raise the current because the MKS Servo42 manual states that the stock value is the max value that should be used for this motor. Also, with the tests done with other allegro drivers, increasing the current didn't help to reduce the salmon skin. Regarding the encoder resolution, from what I see, it has a very good resolution so I don't think that is the issue. Not only the DRV8825 drivers have issues with salmon skin. The allegro A4982 also have this issue (see my analysis video here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-78fonMoXRuA.html ).

Hi Trampas, I'm running my printer with Smart steppers (FW0.37). Earlier when running the printer in regular cartesian XY, prints were good. Now with it setup as a CoreXY , I've been introduced to severe salmon skinning on all surfaces. Maybe some tuning is in order for this kind of setup?!?

@@human2761 What controller are you using? The Duet has some acceleration math bugs for coreXY, which I have seen causing problems. Also with the CoreXY it is critical that the both motors accelerate the same and respond the same, so try slowing down the maximum print speed and see if this fixes/reduces the problem if so let me know. Specifically I am worried that if you tell bot motors to move 10 steps and one has an error and takes slightly longer to move it will cause more issues on coreXY, if you slow controller down and problems go away then this might be problem. Another issue might be the ringing on the PID tuning. For this try dropping the P term to 0.4 and I term to 0.0004 and d term to zero. This might reduce the ringing due to lower P term and hence reduce salmon skin effect. However by all means let me know and also check the Smart Stepper group: groups.google.com/forum/#!forum/smart-stepper

Thanks :)

I think that the problem rises from the driver's zero-crossing anomalies and can't be filtered or fixed.

Since this is a ripoff of the Smart Stepper from misfittech, it should have the same calibration routine which deals with this issues. They skimped on some components, so that might cause some issues. You also have to do the calibration for it to be effective....

Hi,Yes, it works with a ramps 1.4. You just need to plug in the adaptor and that's it.

can't you listen? he fucking says it's a plug and play system and you don't need hardware or software changes as long as you can swap the stepper drivers.

Thanks for the feedback Jim. Regarding the TMC2208 on the black widow, i did the same thing as in my video of the MKS GEN L upgrade. Same jumper configuration.

If you need good precision and level holding on the Z-axis, a 0.9 degree stepper and a good quality 2mm pitch lead screw will do an excellent job for much less money (5 micron full-step accuracy and very resistant to back driving). A servo is way too expensive for what it's worth on a Z-axis.

@@KarriKoivusalo This is a Nema17 stepper with closed loop feedback. I got them for $20 a piece assembled. So I can keep my original leadscrews and carriage assembly exactly as it is. I am not sure how a 0.9deg stepper which usually cost more than $20 and a new leadscrews and a new carriage nut which hopefully fits my carriage is going to be cheaper,much less if it does skip a step it's done being level. I do run Marlin 2.0 with auto z align before every print.

If you have a problem with Z-axis losing steps, it's a failure on the stepper motor part. Are you sure having the cheapest of the cheap parts is going to fix it?

@@KarriKoivusalo Well I am not having lost steps, but I don't care who you are what machine you are running, but on a dual Z independent gantry you will have some skipping. That is just a fact no system is perfect. If they were why in the world would most every precision manufacturing machine use closed loop servos over open loop steppers. I can tell by doing a Z auto align after a print that there is some small step loss. It is pretty minimal but it is there no the less. If you look at your prints you probably will see some very small tell tale signs like one layer looks just a bit squished . I did this mainly to test out how well it works, so far its pretty interesting. I might have some setup issues. Upon re-enabling of the stepper drive it goes to the calibrated position don't know if that is good or bad, but if you set it high it goes up to the top and very rapidly at that, if you set it low it could hit a print if you dont do it right. most of the time You would remove the print before doing this but... I was thinking mostly to see how well this would work and if it does, which it seems to, why not design something like this with say a TMC5160 or 2209. Closed loop has a very strong appeal to it regardless of how good you machine is. I can say that I am able to achieve much higher velocity with my Z-axis now. It could be the bigger motors over the stock ones, but I would lose steps if I tried to go over 12mm/sec now I can achieve well over 20mm/sec without skipped steps. Why is this important you may ask well I can say that I have shaved a couple minutes off of a 2 hour print in just the increased speed in my Z-Hop, and my prints are dead on in the layer heights. And no I did not cheap out on my printer, well perhaps when I started I did as I bought a Anet E12, but its pretty much a from scratch printer minus the base frame and heated bed platform. Now its a SKR Pro powered linear rails for z All Metal Nickel plated copper V6 BMG direct drive using mostly TMC2209's minus Y which is a TMC2160 with a .59NM stepper , homebrew heated space, Cant call it a heated chamber due to statasys.

For Reference here's my printer before the closed loop stepper upgrade, I will make a timelapse of something after its done. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-IjOEsf_gr14.html

Hi, the salmon skin if from the driver and not the board so even if you buy the motor board alone it will not fix the salmon skin. The motor board can be used with any nema 17 motor but you will need to add a small magnet on the motor shaft for it to work.

@@ruiraptor Thank you for the quick reply!

@@ruiraptor Hi, I bought the board and driver alone, it didn't include a magnet. Can I use a normal round magnet and what is the correct procedure in attaching it to a Nema 17 motor?

Hi Vance, I agree. I would like to see this motor with a different driver.

@@ruiraptor Perhaps one will appear once the salmon skin becomes common knowledge.

@@linma1587 Thanks for sharing this information.

They is an option. ustepper.com/store/ustepper-boards/26-42-ustepper-s-lite.html#/28-connector-dc_jack/31-stepper_motor-no_stepper_motor

Hi, regarding your first question, yes, you can choose a smaller microstepping. Regarding the limit switch, this board/driver does not support sensorless homing so you need limit switches.

@@ruiraptor Thank you for your fast response !!!

Hi, we will review a better motor soon and we will try to include that information.

it is possible you may need to update the firmware of your control board. try their git hub for that github.com/makerbase-mks/MKS-SERVO42B

That makes absolutely no sense... By your logic your heatbreak is acting like a impact absorber since the motors will be travelling past the point of contact as you say... If it was closed loop the stepper motor would know exactly where it is at and if the slicer profile was correct and there was no path that the heatbreak would contact anything then you would never have any contact to begin with

The servo42c does true field oriented control, which is why it uses 8 MOSFETs - that's the correct way to do it. The version shown in this video is closed loop, but isn't actually field oriented control, it's just a regular stepper driver. "Closed loop" and "field oriented control" aren't the same thing. Field oriented control creates a magnetic field based on actual rotor position relative to the stator to create maximum torque. It is _also_ closed-loop at the absolute positioning level. Regular closed loop control without FOC is only closed loop at the absolute positioning level, but it doesn't care about rotor position relative to the stator. The driver algorithm at that level is still the same as a regular open loop stepper.

We didn't try with higher microstepping because at that time we only had an 8bit board and that type of board cannot handle higher microstepping.

No, that is not possible. But you can find some closed loop motors with TMC drivers in the market.

Yes, you can use arduino to control this stepper motor. The driver is included in the motor so you only need to send the control signals.

So I am using this system with an MKS Rumb32 and cannot recommend it. Even at 256 microstepps it is loud, you can't compare it with the TMC 2130 that I had installed before. Even the Rumba32 had to be modified to run with tmc2130. The print result for the TMC2130 is not much better. Here, savings were made at the wrong end. I don't recommend buying it or you can live with the volume. I am disappointed.

The board already includes the driver chip.

ustepper.com/store/ustepper-boards/26-42-ustepper-s-lite.html#/28-connector-dc_jack/31-stepper_motor-no_stepper_motor

@npgoalkeeper _ how do you figure that?

A servo controller needs to have a full H-bridge PWM driver to work; a stepper driver works differently and wouldn't do.

Hi Julien, Not with this 8bit board. Only with a 32bit board you can try the 1/64 microstepping.

@@ruiraptor should work with Klipper firmware

Hi Joe, I'm currently testing exactly that. It seems to be yes. When i finish these tests i will update the information in the video description.

I normally don't use higher microstepping values with 8bit boards. Perhaps with a 32bit board such as a lerdge that test can be properly done.

@@ruiraptor So were you using the same microstepping value for the TMC drivers?

Correct. I used the same 1/16 steps for the TMC drivers.

I currently have an MKS GEN L board and increasing the microstepping with this 8bit board is not a good idea.

Yes!

Hi Thomas, yes, I did that test while the motor was on my hand. If you try to rotate the motor shaft, it will return to the original position.

Thanks for replying :)

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Hi, I did try that. I jammed the motor shaft for a second when the motor was moving the axis a long lenght and at the end the carriage moved the same amount that i told it to move.

@@ruiraptor Did the other axis's get out of sync? I was worried since just the stepper itself is closed, but there is still no communication back to the MKS to tell other steppers to wait until its back in sync right? Did you do that in the video? I dident see that.

That is correct. There is no communication back with the board and the other motors so if you jam one of the axis the others will still continue. The jammed axis will recover but depending on the movements the printer is doing, it might not be fast enough to recover without getting layer shift effect.

Yes, it will, the motor will only lose step temporarily, but will continue to try to catch up with the correct amount of steps

Hi Julien, no, it's not compatible with the SKR mini E3 V2.

i bought the bigtreetech s42b ender3 kits for $16 each without the motors because i use 920z in 2.1a steppers. they come with a small adjustment wheel is the only difference between the models in the bigtree lineup. but it is made for the ender3 and they have a page with the firmware for all others if its needed to change to make it compatible for the 4988 drivers. as for thee mini i dont know about clearances because you are adding about 10mm to the length of the motor

Hi Vega 128. That's not that easy to do :) Furthermore, there are surrounding components that are different between drivers too.

ustepper.com/store/ustepper-boards/27-46-ustepper-s.html

@npgoalkeeper _ how so? This uses a magnetic position sensor just like the uStepper

Boa noite Tiago, segundo a MKS, a voltagem máxima recomendada é mesmo 24V. Se for usada uma voltagem maior poderá haver alguma instabilidade.

Muito Obrigado Mas mesmo assim vou tentar puxar isso mais um pouco para ver o resultado... Ver se corre bem 💣💥🙄

Hi, No, we didn't show how fast the motor can go because it can turn faster than the printer's axis can handle.

@@ruiraptor in a 3d printer it is belt driven, but on a spindle transmission higher speeds are desirable. I was interested in your video because few hours earlier I wanted to buy that motor:)

Yes it works.

Yes, you can connect it by USB to a terminal software and control it, calibrate it or change some parameters.

@@ruiraptor thank you, but may i connect a LIMIT SWITCH too, or THEN i need a COntroller again?!

Hi, At first sight, the makerbase looks more complete as you can add the display and see information on the screen and quickly change some settings without the use of a computer. Both use the same driver so i suspect that the mechaduino should suffer from salmon skin as well.

@npgoalkeeper _ could you give some explanation how to tune PID loop? I've got the BigTree Closed Loop Kit and would be interested in your experience. Thanks!

@npgoalkeeper _ Thanks very much for your quick response. I'll take a look at the documentation.

@npgoalkeeper _ Here is the doc for the S42B from BTT. On page 14 you can see where you can tune the PID github.com/bigtreetech/BIGTREETECH-S42B-V1.0/blob/master/42%20Stepper%20Motor%20Closed%20Loop%20Driver%20Control%20Board%20Manual.pdf

This is the one for nema 17

Did a 20mm cal cube recently, about the same accuracy as before.

@@nathanmattison474 is it 20mm exactly or a few mm smaller/larger? How much is the error in mm approximately?

@@calvin-7540 Well, my printer was usually off by +-0.2mm depending on flow rate. At 100 percent flow rate, it was 19.93mm in the x and y which are the axis I out this type of stepper. However mine is a 7 pin Chinese clone, same concept, but mine doesn't have a USB and other stuff. So you could say it did better, but I attribute that more to just the conditions at the time like maybe my garage was warmer then before, etc...

@@nathanmattison474Thank you for your reply. If I am not wrong, the makerbase brand is from China as well, so there is very little chance to have clone in the domestic market in China【almost all China clone products available overseas can be found in China market as well (Taobao)】, maybe your one is the latest 42B version which the manufacturer eliminate the USB port.

www.ebay.com/itm/174214691602 That's the one I bought.

It might be incremental but it's all done internally on the small board.

These kind of servos are universally based on magnetic sensor which detects the angle of the magnetic field from the magnet on the end of the shaft, so absolute.

@@KarriKoivusalo so in case the power goes out, the servo still knows in which position it is, isn't it? I would never have to do a homing right?

@@manuelrodriguezlatorre8978 Homing would still be needed in most cases; while the driver knows the shaft angle on a single revolution, it has no way of knowing how many revolutions the shaft has done while out of power. On a blackout resume with everything held in place it could resume with complete precision.

According to the specs of the sensor found in the link, it's a high resolution angle sensor "The A1333 is a 360° angle sensor IC that provides contactless high-resolution angular position information based on magnetic Circular Vertical Hall (CVH) technology. ". Link: registration.allegromicro.com/#/parts/A1333

Yes, they are compatible with ramps. The connection should be very similar with the connection made with the board in the video.

@@ruiraptor Thank you! Another question: what magnetic encoder does it have? (from what I understand in your video you have MKS SERVO42A, not the newer MKS SERVO42B which has Allegro's A1333LLETR-T). Is it AD5047D?

The new MKS Servo42B we don't have yet. We might test it soon.

Hi, The 3d printer boards are normally equipped with Sanguino or Atmega microcontroller chips and programmed with arduino IDE, so yes, you can.

@@ruiraptor I meant can I control it as a standalone directly using an arduino and a stepper driver ? I plan to use it for a model railroad turntable.

It depends on the project...the stepper motor can be used but the size and weight might be an issue if your robort is small.

@@ruiraptor my robot is rather large so that won't be an issue.

Yes of course these can be used for any application a stepper motor is used. There is no downside to closed loop

Hi Domenico, I'm currently testing it on the extruder :)

@@ruiraptor How did it go?

@@sirkojac , at first it was very interesting as I was getting perfect filament output (and it was always consistent for different filament types and speeds) but then I started to get different results depending on the model. It's very difficult to dial in the profile so I eventually stopped the tests. I might get back to this later when I have more time.

no

you cannot use this on an extruder. what happens when you get a clog. it starts skipping. it will then try to compensate and skip even more. and more and more untill you break something. what happens when you don't get a clog but it still skips. then you get a part of the print where it skipped so you have underextruded. and then it compensates by overextruding on another part of the print because it's already passed that part of the print.

I was expecting some interesting results but sadly it didn't work as good.

@@ruiraptor Thanks for the info

What was the result that lead to this conclusion? I am direct drive so I won’t use this anyway but I am curious what was bad.

Backlash comes from the mechanical pieces like the leadscrew nut. If you had the encoder along the axis then you could control the backlash electronically. Here you have the encoder in the motor it self so no.

No you cannot. The driver is included on the small board.

@@ruiraptor does the driver on the board make much noise compared to the stock driver

It makes the same noise. The driver on motor's board is also an allegro.

@@ruiraptor I dont understand why they would go to the effort of creating this then put an old driver on it

It's not a stepper driver, it's an H-bridge driver. You cannot use any stepper drivers with this control method.

also notice that it looks like the board which does actually the closed loop stuff looks like it could be moved to another stepper no problem. You could have reduced salmon skinning by increasing vref as well.

Hi, I actually tested the close loop feature (mentioned that in another comment here). I rotated manually the shaft and it returned to the initial position. Regarding the salmon skin and vrefs, I followed the manufactures advice on max values and tested. The salmon skin is not fixed with vref adjustments.

@@ruiraptor Increasing Vref decreases the amount of móire. It is probably missed microsteps which causes it, well that is my theory in any case. MFG recommendations are a bit so so, it is like they would sell you bicycle which they say can only do 5km/h, or this another 10km/h. Just step up the Vref; If you cannot boil eggs on driver or the motor, you are all ok :) Joking aside, i try to keep my motors and drivers below 80C, often around 60C (60C = very uncomfortable to touch, but ok) That was not sufficient test of closed loop as just watching flag on it does not give any idea did it return to exactly right spot, that test should have been done during print, so if it did not return to exactly right spot, it would be veeeeery obvious. Mid print you will easily see if it missed by say 0.1mm :)

360 / step angle

also there are usually 2 types of stepper motors for a 3D printer. If it is a 1.8 degree stepper it is 200 steps. If it is a 0.9 degree it is 400 steps.

The company that made it will provide that

Hi, I find it hard to believe that the salmon skin is created by having one Allegro on the Y axis and one TMC on the X axis. Why do you think that?

@@ruiraptor thank you for your answer. Actually I am not fully satisfied by my position either 😅. Full reasoning is a bit long, so I will keep it short: the servo motor has >0.02mm EFFECTIVE LINEAR resolution, and the A4954 is not a stepper driver but a "generic" PWM full bridge driver. All the calculation is made by the MC. Hence if anything wrong with this servo then it should be bad MC choice /code or too low resolution hall effect sensor, not the "driver". Otherwise it might be that the difference of linearity between the servo and the TMC22030 + stepper emphasizes an otherwise unknown non-linearity of the TMC driver interpolation, hence my previous answer.

Hi Jean-Philippe,Thank you for your explanation.That would probably make sense if you were working with a delta system or a corexy where you need to have both X and Y axis working together. In this case, where you have a Cartesian printer with independent moving axis, I don’t think so.Regarding the hall effect sensor, this one is actually very sensitive as I show in the video.

@@ruiraptor There might be hope for 32-bit controllers using this servo at a higher step rate. I might be wrong, but I suspect the reason the TMC2208 drivers work so well at eliminating salmon skin is because they are actually running the motor at 256 micro-stepping when in SpreadCycle mode. This why the TMC SpreadCycle technology is so quiet, the TMC driver is just taking your 1/16 micro-stepping signal from the controller and bumping it up to 256 micro-stepping. I would be curious to see if the TMC2208 driver produces salmon skin with the SpreadCycle mode disabled via driver jumper settings.

Hi Kyle, I will try to test with a higher micro-stepping soon and will let you know. Regarding the TMC and why they don't have salmon and are so quiet, I'm not so sure about that and I would bet that they will not produce salmon skin with spreadcycle disabled.

Hi, yes you can.

@@ruiraptor thank you sir😊

Exactly. No firmware change or installation required. If you need to change some parameters like motor direction, microsteppings, etc, you can do it directly on the motor

ruiraptor can you Tell me which cables i have to swap to change Direction? Ty in advance! Chris

@@JustAValidName89 You don't need to change any cables for motor direction. You can access the motor using a USB cable and edit the firmware by sending a few commands or get a display and change the motor direction using the display.

ruiraptor ty for the fast reply but i asked my question on the wrong Video..... i Wanted to ask this for the trianglelabs Dual extruder Motor Setup on my tevo Tornado..... i already deleted the Post But it Looks like that did Not work 😅

@@JustAValidName89 , for the BMG extruder on the tornado, install the extruder the other way around instead. It will work the same but the differences are that you don't need to reverse the direction and it will be easier to handle with it.

Hi, wen we made the video, there was only the 42. Now MKS has the 42b. We didn't test the 42b yet.

@ruiraptor looks like they gave you props when designing Rev B: github.com/makerbase-mks/MKS-SERVO42B They also open-sourced the firmware.

he calls it allegro because on the servo there is an A4954 Dual Full-Bridge DMOS PWM Motor Driver installed to power the motor :)

It will recover and continue at the correct position but it will not go back and redo the missing steps

Turns out SKR v1.3 boards only put out 3.3v on the stepper driver logic Vin. Had to tapp into the servo which has 5v because the encoder runs 5v. Got it to work finally, actually works pretty good, I knocked the axis while printing and it came back and continued printing where it needed to.

Hi, you don't need to make any changes in the printer's firmware when using this motor. Step and direction can be changed in the motor.

I have this same error with mine. Its a 7 pin version though from Ebay and no reset button. Did you ever figure this out? I'm about to return to the seller because they are not helping.

Figured it out with the supplier, the VIN input to the STM32 chip, has to be 5v, my skrv1.3 from Bigtreetech only puts out 3.3v.

Closed loop stepper. It's a bit of a hack on top of a Stepper to make a more servo-like behavior without needing to make a bunch of changes to deploy a major increase in speed and precision.

The ideal would be using trinamic drivers instead of allegros.

Yes it is

thanks captain obvious. you saved the day.

@@johnhenry1300 i do what I can

@@ChrisbottrellphotographyCoUk its good to have you on our side... if you were to use your powers for evil... oh boy we'd be in trouble.

According to the specs of the sensor found in the link, it's a high resolution angle sensor "The A1333 is a 360° angle sensor IC that provides contactless high-resolution angular position information based on magnetic Circular Vertical Hall (CVH) technology. ". Link: registration.allegromicro.com/#/parts/A1333

Hi, Do you mean for X and/or Y axis?