Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
 

Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)  

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Omnissiah
(@omnissiah)
Eminent Member

Looks like the worse print results I'm having with 3.9 are not related to the steppers. It's a Prusa bug. https://github.com/prusa3d/Prusa-Firmware/issues/2693

Posted : 09/06/2020 8:03 pm
manuel.s
(@manuel-s)
Estimable Member

Hello fellow modders,

So i decided to join the bandwagon with the moons to get rid of my VFAs 🙂 MK3s here with a few mods.

My setup is as follows:

- Volcano hotend to print faster, Mod for full build area by m wolfe.

- Steel springs under the bed to get it 100% flat.

- Drylin bearings in Y and X.

- Custom firmware to get the 3.9 to work properly with my setup.

I think they changed the voltage or something as i use drylin bearings in X and Y i have another resistance and the selft test never finishes also for the "new bed" i need to make some finishing touches.

So my first question is:

What motors are the best for the X and Y axis ?

There were several in the testing in those 47 pages and i lost count/oversight.

What i want is an easy upgrade. Like switch out motors for X and Y and change the  firmware rotation numbers to double the original numbers to account for 0.9 motors instead of 1.8thers

So that brings me to my second question:

What lines of code needs to be changed in order to work with the new motors successfully (3.9)?

I will most likely not go beyond 3.9. Every update i do less stuff works on my machine.

As i said i seem to have a special setup and i have to do some tweaks to the firmware to make it work on my machine anyways.

I see that there is some source around and i could use this as a base and do my things with that if i have the same motors as that person.

So this depends on the answer above.

Could somebody point be to the right starting points ?

Thanks so far.

Have a great day!

This post was modified 2 months ago by manuel.s
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Posted : 11/06/2020 4:14 pm
holmes4
(@holmes4)
Estimable Member

Recommended motors are in the "readme" at the github page (scroll down) for @guykuo's firmware. I would recommend using Guy's firmware for now, which is still 3.8.1, rather than 3.9 as there appear to be some significant print quality issues with 3.9. I had to order the steppers from Moons' website directly, as they were not available on Amazon when I bought. I see that Moons' is selling them through Amazon, but shipping is high. Compare prices - I ended up adding a couple of vibration dampeners to bring the total over $100 for free shipping, which was less expensive than otherwise.

Instructions for what to change are also in the readme.

Posted : 11/06/2020 5:20 pm
chocki
(@chocki)
Prominent Member

The stepperonline motors work just as well, seem to have less bad motors and are considerably cheaper. They are a little bit louder, but if you place your printer on a granite chopping board or concrete slab and have this on sorbothane dome feet, the noise / vibration is so much reduced, you will wonder how you ever managed to sleep before.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 11/06/2020 5:40 pm
vintagepc
(@vintagepc)
Noble Member

Can vouch for the SO motors. I'm using them with stock firmware.

 

Posted : 11/06/2020 5:42 pm
Lukas Hejtmanek
(@luka-h19)
Active Member

Just be aware, that stepperonline motors are weak. Have only 0.36Nm (Prusa recommended are 0.5Nm) and they also have high inductance, which means that they quickly loose torque. Also be aware, that stepperonline motors produces lot of vibrations with TMC2130 (TMC2209 are far better here). 

Posted : 11/06/2020 5:49 pm
manuel.s
(@manuel-s)
Estimable Member

Hi Thanks!

@vintagePC are the 1.8 SO an improvement to the prusa ones ? How much improvment ? Do i need soldering skills ?

I looked at the pictures/readme in the Github and it seems quite a task to change those motors. It seems i need to solder some cables and need to set esteps.

What would be the correct esteps for the prusa geared extruder ? This semms not to be mentiond in the guide. Do i need to set the estps even if i do not use 0.9 extruder motor ? Do they have to be set also with stock prusa motor ?

How important is it to switch the extruder motor as well ? Can i use a 1.8 SO or Moon as a drop in ?

What are the correct values for linearity correction for y and x axis ? How do i set them ? How would i turn of linearity correction for y and x if i use original Moons ? The guide is sadly not so clear about that part.

What StepperOnline Motors are you using ?

Thanks again!

...
Posted : 11/06/2020 6:08 pm
chocki
(@chocki)
Prominent Member

@ vintagepc - are you using Linear Correction with the stock firmware?.

I take it you have just altered the TMC2130_USTEPS_X and Y from 16 to 8 value for the 0.9 deg motors and because of the skelestruder Z_MAX_POS to 220 and DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,490}

Is everything else stock?

 

Thanks

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 11/06/2020 6:14 pm
vintagepc
(@vintagepc)
Noble Member

I did not find linear correction to have any noticeable impact. I also did not alter any of the constants in the firmware. All of the parameters were changed with M350 and M92. 

For the 3S, you have to leave Max Z alone or it will fail Z calibration. The skelestruder Z change is very close to the change from the 3->3S extruder so it just works as-is

Manuel - I am using 0.9 Stepperonline/OMCs. You will need to solder the wires or crimp your own cable, yes. It does not come with long enough leads nor a molex SL connector. 

Print quality is incredibly subjective but I have posted some pictures somewhere in this thread, IIRC, and I'm satisfied with the results. (It's worth noting that I also have a skelestruder and vesconite bushings, both of which may contribute something to the end result. ) I definitely no longer get that salmon skin pattern, the most visible artifact on my prints now is ringing on sharp edges. Flat faces are buttery smooth. 

Posted : 11/06/2020 6:26 pm
chocki
(@chocki)
Prominent Member

Thanks, I'll give it a go and see how it works out on mine, but I will have to change the Max Z and the PT100 heater block thermistor setting.

I also use my own PT100 thermistor table as it is more accurate than the existing firmware, it was calculated / simulated using SPICE and finally tested and matches against E3d's tables and is a lot smoother than the existing set of figures which jump about somewhat.

While I am at it, I hard code my particular PID values just to save me having to run calibration 😀 

It will be interesting to see how it compares, but first I need to print out some before examples.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 11/06/2020 6:41 pm
vintagepc
(@vintagepc)
Noble Member

Yeah, there's a bug in the stock table

https://github.com/prusa3d/Prusa-Firmware/issues/2621

 

Posted : 11/06/2020 7:04 pm
chocki
(@chocki)
Prominent Member

If you want the correct table values for a PT100 with amplifier hot end, here are the values:

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../pt100-with-amp-board/paged/5/

Just replace the values in thermistortable.h thermistor table 247 with the values in the link.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 12/06/2020 8:58 am
manuel.s
(@manuel-s)
Estimable Member

Hi guys,

So i've gone through the github and orderd what i could find.

But i have a few more questions:

If i stick with the standard prusa extruder from the mk3s. What Esteps do i need to set? I guess its a non geared extruder right ? Do need to touch the M350 Command ?

Also where could i buy the specific moon motors in Germany or Europe ? 

As i understand i would just have to set:

#define X_AXIS_MOTOR_09 //kuo exper X axis
#define Y_AXIS_MOTOR_09 //kuo exper Y axis

I would NOT set any Extruder related stuff correct (because i keep the same as before ?)?

Also i would not set any M350  command ? correct ?

Lastly with original Moons it should not matter if i use Linear Advance and will keep the Kxx line in the Gcode. Is this still the case  ?

Also Kuo talk about setting linear correction once. What is this  (i asume its linear advance but not 100% sure) ?  Does this have to be calibrated to the hotend or to the motor or both ? and  what Value would i have to use with the original Moons ? This part of the github page is not very clear to say the least.

Im looking forward to my moons 🙂

Thanks again and have  great week and stay healthy

On a side note; It seems many of you switched out the thermistor from e3d. Is there a reason for it ?

 

This post was modified 2 months ago by manuel.s
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Posted : 15/06/2020 10:49 pm
houndb
(@houndb)
New Member

I have a off topic question that I hope you guys can give me some advice. I have a creality ender 3 pro that I will be upgrading to a core xy system printer and would like to purchase new stepper motors for the project. It is powered by a stock 350 watt power supply with an upgraded board SKR MINI E3 32 bit.

 

Will the moon stepper motors MS17HD2P4100 be a good fit. Do you suggest something different? The upgrade manufacturer states that any stepper motor that works with the stock printer will work with the upgrade.  The reason  I want to upgrade the motors is because of the press fit pulleys.

 

Thank you for your time.

Posted : 16/06/2020 2:50 am
ricardo.f2
(@ricardo-f2)
Active Member

So I have the SO 0.8 stepper lying around here, but somehow it is currently not going on with the FW.
What should I do? My printer already has 3.9.0 on it. Should I rather wait until a new version comes out of here?
Since I had some problems with 3.8.0 and did not want to go back.

Posted : 19/06/2020 6:25 pm
Lukas Hejtmanek
(@luka-h19)
Active Member

@ricardo-f2

What does it mean, it is not going on? It does not rotate at all?

Posted : 19/06/2020 6:27 pm
halvim
(@alvim)
New Member

Hey guys,

Based on this thread, I have decided to install Moon motors (MS17HA2P4150) on all axis.

I am having a hard time to make the Z axis move properly. It is very noisy (grind noise). Could you guys let me know what changes on firmware I should make?

Thank you very much.

Posted : 21/06/2020 6:12 pm
delamarre.frederic
(@delamarre-frederic)
Eminent Member

Hi all

I have OMC 0.9 for X and Y working nicely since the beginning, but i wonder what parameter can be tweaked to avoid "squeeks" during deceleration.

Posted : 25/06/2020 9:32 am
Lukas Hejtmanek
(@luka-h19)
Active Member

@delamarre-frederic

maybe try decrese acceleration limit to 750mm/s^2. For me, OMC 0.9 motors worked best with 16 microsteps and TMC2209 drivers. None is possible on legacy prusa board.

Posted : 25/06/2020 9:59 am
JeffyW
(@jeffyw)
New Member

I recently decided to upgrade my MK2 to MK3S, but after ordering the kit and reading various things like this thread, I decided to just fill in the rest of the missing parts from the upgrade kit and end up with 2 machines.  In particular that meant I picked up a set of StepperOnline 0.9's (and a BMG).

I took the changes from Guy's branch and merged them with the official 3.9 branch.  It prints really nice, but I'm finding that sometimes I get layer shifts, always on the X axis, always to the right side, and I think it's only occurred when printing in stealth mode.  Furthermore, when in normal mode with crash detection on, it has detected a crash a few times and upon homing and restarting, I see an ever so slight layer shift (maybe .5mm?).

I'm trying to pinpoint the cause and slowing trying to eliminate variables.  At first I noticed an issue where the Prusa Drybox I have mounted on the wall was requiring too much force to pull filament through at certain angles, which I thought just created too much pressure as the motor tried to pull the extruder, so I moved back to a mount above the printer.  I noticed my belt tensions seem to report much lower numbers than recommended (178x/203y), but I also saw a post from @chocki that suggested the number might be lower for .9s.  I have heat sinks on the reverse side of the board and can definitely feel heat on the outside of the einsy case.  It doesn't occur at any specific layer height and doesn't seem to be perfectly repeatable.

Full disclosure, I do have igus bearings on and acknowledge that could contribute, I also didn't cut a hole in the einsy case where the heat sinks are, just put the sinks on there, so there could be overheating.  Oddly enough, while the layer shifts all appear to happen in the X axis, the printers failure stats report only Y axis crashes.  I've since turned off crash detection (because it was only resulting in errors).

I'm mostly assuming that the layer shifts are a result of one of the above factors, but not quite sure where to start.  Since the shifts themselves only seem to occur in stealth mode, could it be that the TMCs are overheating?  Could belt tension / bearing issues cause the motor to draw too much current, thus either exacerbating any temperature problems or potentially causing a false crash?  Does anyone have suggestions on where the belt tension numbers should be with .9s?

Thanks!

...
Posted : 25/06/2020 7:55 pm
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