Very slight systematic waves every about 2mm on the prints

luc

I was able to find a way to turn the belt temporarily just to make a print.

The cause is not the belt or even the pulleys.

I'm beginning to think it may be the motors:
https://www.omc-stepperonline.com/it/nema-17-bipolare-0-9deg-46ncm-65-1oz-in-2a-2-8v-42x42x48mm-4-fili-lunghezza-d-cut-completa-17hm19-2004s1

What are your thoughts on these motors?

droftarts

@luc The motors seem fine, but it might be an imbalance in how the coils have been wound. What hardware and firmware version are you running? Send M122 and post the response. Also please post your full config.g.

Ian

luc

@droftarts said in Very slight systematic waves every about 2mm on the prints:

@luc The motors seem fine, but it might be an imbalance in how the coils have been wound. What hardware and firmware version are you running? Send M122 and post the response. Also please post your full config.g.

Ian

Here is what is required
Thank you

config.g
M122.txt

droftarts

@luc I can't see anything obvious in your config or M122 that would be causing the issue. You could try using the latest 3.6.0-rc.2 firmware to see if it makes any difference, but I'd think the issue is either the motors as already discussed, or mechanical, ie a bad bearing on the belt run (if it affects all axes, look at the bearings not on the X carriage, as those don't move with Y axis movement). Overtightened belts can also cause issues. Finally, check that you haven't mixed up the belt and pulley types, ie running Gates GT2-2mm belts with 2GT pulleys, as the tooth profile is very slightly different.

Ian

luc

@droftarts
I don't think it could be the firmware but I'll try it last.

All pulleys and bearings looked good but your point about doing it on all faces I could I had to check to rule out the fixed bearings not on X axis was very helpful in fact, since I had them new, I decided to change both bearings and pulleys.

I made a test print afterwards and did not solve it so I think it is useless to disassemble the other 4 X-axis bearings.

I only have one new motor in reserve. I don't know if it is worth doing a test by changing only one motor or is it better to do both together.

Edit
For GT2 or 2GT: With both old motor pulleys and belt and new ones I tried to see conme copied one over the other and I don't seem to have any doubts about that. They look okay to me.

Edit2:
Changed the left engine: Nothing....all the same as before!

luc

hello, it seems that my problem is identified with the term VFA “Vertical Fine Artifact” and it seems strange to me that from what you read around there is no solution.

What do you guys think about this?

https://ellis3dp.com/Print-Tuning-Guide/articles/troubleshooting/vfas.html

https://www.youtube.com/watch?app=desktop&v=-et5eMyLlUs

https://www.google.com/search? q=VFAs+%28Vertical+Fine+Artifacts&client=firefox-b-d&sca_esv=cc91aa7b516a412e&ei=1egHaKX7EZCN9u8PlJz78AQ&ved=0ahUKEwjluYKEq- yMAxWQhv0HHRTOHk4Q4dUDCBE&uact=5&oq=VFAs+%28Vertical+Fine+Artifacts&gs_lp=Egxnd3Mtd2l6LXNlcnAiHVZGQXMgKFZlcnRpY2FsIEZpbmUgQXJ0aWZhY3RzMgUQIRigAUiMCVAAWABwAHgAkAEAmAGJAaABiQGqAQMwLjG4AQPIAQD4AQL4AQGYAgGgAowBmAMAkgcDMC4xoAe0AbIHAzAuMbgHjAE&sclient=gws- wiz-serp

I have TL smoother that I used on an old printer. Can I try them on the duet 2 wifi or do I risk damaging the board?

droftarts

@luc said in Very slight systematic waves every about 2mm on the prints:

https://ellis3dp.com/Print-Tuning-Guide/articles/troubleshooting/vfas.html

This seems like a sensible page. It focusses particularly on belt/pulley/idler teeth for ~2mm spacing VFAs. I think this is the most likely cause of your ringing, mainly because the VFAs from a 0.9 degree motor doing 160 steps per mm like yours would be much closer together. VFAs from motors usually show up between one full step and the next. On a 1.8 degree motor 80 microsteps per mm, assuming x16 microstepping, the VFAs are 0.2mm apart. On a 0.9 degree motor like yours, they'd be 0.1mm apart, which is why they are less noticeable.

I don't know enough about the Prorifi3D motors to know if they are any good. I know Prusa spent a lot of time improving their stepper motors, and switched from 1.8 degree motors to 0.9, but still have VFA issues, even on the new Core One. Prusa introduced Phase Stepping on the Prusa XL, see https://blog.prusa3d.com/phase-stepping-how-we-busted-vibrations-and-improved-print-quality-on-the-xl-printer-with-just-a-firmware-update_94793/, but that only works with certain TMC drivers; 2240 on the Prusa XL, and 2160/5160 like on the Duet 3 6HC (though Duet have only partly enabled Phase Stepping so far).

TL smoothers were made to address a specific design flaw in DRV8825 drivers, and helped a little for old A4998 drivers. As far as I know, they won't make any difference on TMC drivers.

If you really want to go down the rabbit hole of looking at the stepper driver and motor, you could look at the developments in Klipper firmware. See
https://github.com/MakerBogans/docs/wiki/TMC-Driver-Tuning
https://github.com/andrewmcgr/klipper_tmc_autotune/tree/main

The idea here is that the default settings of the stepper driver may not be ideal for your motor, and that you can change the stepper driver settings to better match your motor. This should work for the TMC2660 drivers on the Duet 2, but hasn't been tested. I don't actually know of anyone who has tried!

Fortunately we don't have to install Klipper to run this; @Falcounet created an online calculator here, and @jay_s_uk made a macro that can run on a Duet, on the RRF Discord here

Using the values for your motor from here:

[motor_constants omc-17hm19-2004s]
resistance: 1.45
inductance: 0.004
holding_torque: 0.46
max_current: 2.0
steps_per_revolution: 400

from the online calculator we get

pwmgrad: 6
pwmofs: 46
maxpwmrps: 11.087794368735375
hstrt: 0
hend: 1

and from @jay_s_uk 's script we get

M98 P"0:/macros/TMC tuning"
pwmgrad = 6
pwmofs = 46
maxpwmrps = 11.08779
tblank = 0.0000019
tsd = 0.0000086
dcoilblank = 0.0115200
dcoilsd = 0.0125280
hstartmin = -1
hstrt = 1
hend = -2
hstrt1 = 0
hend1 = 1

The next bit is tricky, and I'm not sure if anyone has managed to get this right. If you have a Duet 3 (with TMC22xx or TMC51xx stepper drivers) you can set the stepper registers directly with M569.2. However, with the Duet 2 and TMC2660 drivers, you are limited to what can be set with the M569 F, C, B and Y parameters. And I'm not sure how those relate to the calculator's answers above. I believe the calculator answers relate to the stepper driver parameter names, so check the TMC2660 data sheet. You can also check at least some of the settings by send M569 P[driver number], eg on my Duet 3 Mini 5+ with TMC2209, I get:

M569 P0.0
Drive 0 runs in reverse, active low enable, timing fast, mode stealthChop, ccr 0x00053, toff 3, tblank 0, tpwmthrs 0 (inf mm/sec), pwmScaleSum 11, pwmScaleAuto 0, pwmOfsAuto 36, pwmGradAuto 14, pos 8

NOTE: Be VERY careful messing with stepper driver registers, it's easy to destroy stepper drivers!

Let me know if that helps.

Ian

luc

@droftarts
I thank you for the very detailed answer that took up a lot of your time for me.

Let's go step by step:
Cases like this, unfortunately, are dealt with by the exclusion technique. That is, you have to check the many possible causes in a way that excludes them one by one and then examine another possible cause.

The mechanical part is the first to be checked, and from the checks done on the pulleys (4 of 8 were fitted new even though they were perfect for me) it did not produce any changes on the prints. The other four that were not replaced before were disassembled and tested by fixing them to a vise and putting them in tension with a belt and they kept swearing smooth so I think the pulleys are all ok.

The belt was replaced. Upon disassembly the old one was not in good mechanical condition even though they looked ok to the eye. The old ones were hard to the touch, almost wooden, and if they hung down they did not stay taut but tended to curve in places.
The new one, identical in make and model to the old one seems a bit too rubbery to me and I am waiting to receive new Gates brand 9 mm belts.

So, I would like to try Gates belts before venturing into the driver talk, which I study in the meantime.

In the meantime of all this, I also tried using Orca Slicer instead of Prusa Slicer and found no difference.

Instead, I found a VFA test inside Orca Slicer setting it with speeds from 40 to 200 mm/sec and got a print where the difference of the vertical lines, even at 200mm/sec was still visible though slightly less. I mean that in the face of a very large difference in speed the lines varied very little but they were present so now I have a doubt if indeed the driver speech is the cause. That said, considering that the common and unvaried part are the non-Gates belts (even if replaced) perhaps I'd better try these before thinking about anything else.

FYI:
My M569 P0.0 response:
M569 P0.0
Drive 0 runs forwards, active low enable, timing fast, mode spreadCycle, ccr 0x101b4, toff 4, tblank 2, hstart/hend/hdec 3/3/0, pos 0

Between yours and mine I notice the difference mode stealthChop / mode spreadCycle

droftarts

@luc worn, stretched belts could cause the VFA. I think it’s worth holding off doing anything more until you fit those.

Between yours and mine I notice the difference mode stealthChop / mode spreadCycle

The TMC2660 drivers on the Duet 2 only support spreadcycle, no stealthChop.

Ian

luc

@droftarts said in Very slight systematic waves every about 2mm on the prints:

@luc worn, stretched belts could cause the VFA. I think it’s worth holding off doing anything more until you fit those.
Ian

Yes I know, but in fact that is why I replaced them. Replaced them, however, with new ones that were identical in make and model to the ones that had aged.
I expected some difference in the prints but instead between the old worn and hard belt and the new one I didn't notice any difference. Incredible but so it was.
I will try the Gates as soon as they arrive.

In the meantime I saw Duet 3 6HC and saw that I could use my 6 motors without expansion board (3xZ - 2 x XY + 1 Extruder) but I also noticed the price.

droftarts

@luc said in Very slight systematic waves every about 2mm on the prints:

I will try the Gates as soon as they arrive.

Ah, right, I didn't see the part where you said you had already changed the belts once. See if the Gates belts help.

In the meantime I saw Duet 3 6HC and saw that I could use my 6 motors without expansion board (3xZ - 2 x XY + 1 Extruder) but I also noticed the price.

Unfortunately, that's the cost of UK manufacture, full-compliance testing, board testing post-manufacture, hardware and firmware research and development, sales and marketing, support and documentation. Our competitors don't incur these costs, and largely rely on the community and open source competitors (like Duet3D) to provide R&D, firmware, and support.

Also, changing the controller board is unlikely to help with the VFAs if they are mechanical or electrical in nature.

Ian

droftarts

@luc Just to confirm this is definitely VFAs in the XY system, not the extruder, please watch these two videos, particularly the second one:
https://www.youtube.com/watch?v=dL6u0UwPJOQ
https://www.youtube.com/watch?v=32dTLRNIYmw

Print this object with your normal settings and see if you get the 'woodgrain' effect: https://mihaidesigns.com/inconsistent-extrusion/

If you get the woodgrain effect, then you'll know if the issue is the extruder. If the lines line up, it's something in your X and Y movement.

Ian

luc

@droftarts said in Very slight systematic waves every about 2mm on the prints:

@luc Just to confirm this is definitely VFAs in the XY system, not the extruder, please watch these two videos, particularly the second one:
https://www.youtube.com/watch?v=dL6u0UwPJOQ
https://www.youtube.com/watch?v=32dTLRNIYmw

Print this object with your normal settings and see if you get the 'woodgrain' effect: https://mihaidesigns.com/inconsistent-extrusion/

If you get the woodgrain effect, then you'll know if the issue is the extruder. If the lines line up, it's something in your X and Y movement.

Ian

Thanks for the information but I had already seen those videos and had filed down the teeth of a gear and made a printout without noticing any difference.

Mine is not wood grain effect.....it's really straight vertical lines...it looks just like VFA.

Consider that in the photo it looks like there are more stripes because of light reflections, but I assure you that the stripes are only vertical.

tas

@luc
Hi @luc,

Are you using Gates pulleys as well? It is very important to have pulleys where the hole is perfectly centered and the perfect diameter. The teeth must be an exact match to the belt tooth pattern as well.

When you place the pulley on the motor driveshaft there should be no play. That way when you tighten the set screws they will not be able to force the pulley off-center.

Best of luck,

Tony.

droftarts

@luc Before going through all of that, did you print a tapered object? Because the objects shown are straight. Another test; do the vertical lines always appear in exactly the same position? If you move the object over 1mm, do the lines move, or do they stay in the same place?

Ian