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

RE:

If your running higher currents then you should fit heatsinks to the board, this is better with a new control board case with more room. 

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

Hi everyone, I am very interested in this topic and I am wondering 2 things:

A) why not apply a gearbox to the X & Y motors (with something similar in the picture) so that they run faster and, theoretically, canceling or masking the VFA.

B) why not replace the belts with lead screws?

Thank's for your replay.

RE:

Well, you certainly could build a reduction set or adapt leadscrews. This would likely interfere with the sensorless homing of a MK3.  The leadscrews give a large reduction advantage without messing with the bulk and belt tension sues of belts.  Perhaps some kind of planetary gearset could also be used?

A simpler way to accomplish this would just buy a Snapmaker which uses lead screws on all axis.  It seems like an expensive purchase but would probably end up cheaper and better than adapting a MK3 to leadscrews especially if you consider the time saved. 

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

Hi, long time no see 🙂 I finally found the time to finish the Taurus MK3 (no S/+) LGX + now with Mosquito Magnum and added the recommended changes from Gabe to the variant file on github. Everything went smoothly, homeing works so I am really happy! Thanks once again Gabe Guy and HBPrint, hope this will be the start of further usefull updates 😉

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

Very happy that it went well for you! Hope you have many an amazing print!

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

Thank you for this post!!!  If I don't go with Prorify3d, then I'll follow your advice on just the extruder motor with the 1.8 moons.

Thank you!!

RE:

@HBPrint

Glad to see this is still moving along!
I had updated KUO's 0.9 Moons firmware to 3.10 last year, and have been using it on a Skelestruder/MK3s variant with virtually no problems on single color prints (fails to calibrate the z-axis). When using the mmu, I can't get the steps low enough for fast retractions, but the print quality is great. Here's a link if you want to compare notes.

https://github.com/bartrv/prusa.9

The prints in the photo are using a .25 nozzle at a .07 layer height, no supports, Moons 0.9 motors on x/y/e

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

Hey guys, great thread!

I have a heavily modified Ultimaker Original, tuned enough that VFAs are quite noticeable.

I switched to 0.9* steppers quite a while ago, but they seem to have quite a bit of VFA ( https://www.omc-stepperonline.com/nema-17-bipolar-0-9deg-46ncm-65-1oz-in-2a-2-9v-42x42x48mm-4-wires-17hm19-2004s).

The early part of this thread seems to lean towards certain 0.9* steppers, but later in the thread I am seeing more 1.8* motors listed. Is this just because people do not want to recompile firmware, or are these better 1.8's on par with 0.9's? Without any firmware constraints, what is the current best value motor?

Does anyone know what part number Prusa is using on the new MK4?

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

I should have also mentioned that I am running a Duet Maestro controller with TMC2224 drivers.

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

Crickets in here!

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

Posted by: @hbprint

Github link for Custom v3.11.0 firmware

https://github.com/Clixster/Prusa-Firmware/tree/MK3_3.11.0_CLX

Thanks - I acquired a second hand MK3S with the MMU, BondTech extruder upgrade, 0.9 degree steppers across the board and a Slice thermistor. The printer came with the 3.8.1 Kuo firmware, but as a n00b, I heeded the firmware upgrade prompt and "upgraded" to stock Prusa firmware. This didn't work too well :).

The previous owner pointed me to this thread, and your branch saved my proverbial bacon.

As an aside, I also got a second MK3S with a bear frame and all the other upgrades (sans MMU). It occasionally resets during printing, and I wonder if there are any known crash bugs in the (Kuo) 3.8.1 firmware?

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

Posted by: @sigurdur-asgeirsson

The previous owner pointed me to this thread, and your branch saved my proverbial bacon.

I'm now struggling with the calibration of the thing. Initially, it was failing on the X axis length, detecting it as 248.75mm rather than 250mm. This was because there's interference at the far end between the wire loom from the extruder and the frame. Since I have custom firmware, I just reduced the limit to 248.5mm and moved on.

Now I'm having trouble with the XYZ axis calibration. It looks like the printer is hunting for the first calibration point in the wrong spot - slightly to the left of the first point. I've looked at the code, and it seems the firmware expects the points to be proximate to specific locations from the X/Y homing, so I don't understand how this could be off on this printer.

RE:

It looks like my problem is at the right end of the X-axis, with interference between the extruder and the ball screw support. I assume this is not the normal homing position of this printer?

RE:

If you look at the typical torque curve for a properly sized 0.9 degree motor, you'll see that maximum torque occurs at 150 rpm. If you don't have gears, your RPMs will be very low and the torque will drop dramatically, so to speak.

Oh I found a post on steppermotor where I did some work on stepper motors and torque etc, this was for a Nema17 stepper motor but might give you some clues as to what to check in your case.

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

Can someone tell me how the wiring should go on the LDO 42sth40-1684mac?

Mine go G Bl Bk R to R Bl G Bk and I'm pretty sure that's not correct.

Is this diagram correct?

https://caribou3d.com/img/cms/Motors/LDO40.webp

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

Is this a modification Prusa users are still doing? Seems really neat, especially after looking at the VFA my MK3s+ makes. 

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

Hello to all,

I was reading this topic really carefully, but despite that I was lost a lot of times. So I would like instead of searching and scratching my head ask a question.

To order Moons stepper motors, here in EU is really expensive. First one motor costs more than 100€ and than additional customs, shipping etc.

But I have home 2 LDO motors 42STH48-168MAC. In that topic was discussion about LDO but for smaller one 42STH40-168MAC. 

I would like to ask if bigger one will also work or not?

If not, there is also option to buy new ones from NanoTec ST4209M1206-A.

Some of specs:

Phase | 2

Step Angle | 0.9°

Shaft | Single

Frame Size | NEMA17(42mm)

Length | mm | 39.5 

Rated Current | A | 0.85

Voltage | VDC | 5.61

Holding Torque | Nm | 0.35

Resistance per winding | Ohm | 3.3

Inductance per winding | mH | 16

Coil Type | Bi-Polar

Detent Torque | mNm | 12

Rotor Inertia | gcm² | 54

Weight | kg | 0.28

Thank you in advance for your answers.

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

Oh my!!!...I want to give a huge thank you to guy.k2 and spacemarine for testing! You guys rock! Steppermotor propose une riche série de produits et chaque moteur possède ses propres avantages et caractéristiques uniques, qui peuvent répondre aux besoins de différents clients et de différentes applications.