RE: VFA Artifacts on X+Y Straight Edges
They are sending me new feet. Though I don't believe for a second that it will help =)
Mine is on a dampening stack built from floor tiles and dampening material of different stiffness per layer, adding much more dampening than these feet, there are still VFAs.
I am beginning to think this could be in the belts themselves, if the part is re-used from other printers it may have worked there but the core XY may simply have other requirements on belt specs, why else would belt tuning have the effect above on the VFAs?
/Anders
RE: VFA Artifacts on X+Y Straight Edges
I wonder if the exact phase at which the belts are anchored to the carriage matter? Could nudging a belt by even a millimeter eliminate the "standing-wave pattern"? It seems some people suffer from severe VFA while others claim to have none at all..
RE:
I wonder if the exact phase at which the belts are anchored to the carriage matter? Could nudging a belt by even a millimeter eliminate the "standing-wave pattern"? It seems some people suffer from severe VFA while others claim to have none at all..
Can you elaborate, what you mean exactly with "phase" and "nudging"? Sounds intriguing to test.
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I thought I'd join the VFA-Test-Club and used my Prusament Jet Black sample for it. Not super happy with the results, but as expected and good enough to keep the printer.
Also did it with Sunlu PLA black, but it looks identically, apart from the Prusament being quite shiny at low speeds and pretty matte at high speeds.
The VFA vary a bit on different angles, but that photo shows the overall result quite well.
RE: VFA Artifacts on X+Y Straight Edges
I wonder if the exact phase at which the belts are anchored to the carriage matter? Could nudging a belt by even a millimeter eliminate the "standing-wave pattern"? It seems some people suffer from severe VFA while others claim to have none at all..
I am not sure that you can do much nudging there. The way the belts are anchored to slits in the print head's carrier plate, I think there is always the edge of a tooth pulled against the edge of a slit, so you can only move the belt in 2 mm steps.
Also, the only fixed "phase relationship" between the teeth on the two belts occurs at the idler wheels which are mounted to X gantry, if I visualize this correctly. (For all other idlers, the "tooth phase difference" between the belts varies depending on the current XY position of the print head.) But you still see belt ripple on surfaces that run purely in the Y direction -- the belts do not move at all on the X gantry idlers while printing these. So I don't think adjusting that phase difference could remove the belt ripple.
RE:
Ok, we're on the same page and you've made some great points. I was just curious if how the belt seats in the carriage during assembly is the one random factor causing some printers to show VFA more than others.
RE: VFA Artifacts on X+Y Straight Edges
VFA is clearly noticeable on my kit printer. I'll let you know if reattaching the belts make any difference.
RE: VFA Artifacts on X+Y Straight Edges
I recently printed the same model on my Mk4S and my CORE One - same settings, same PETG filament profile (but different brands), same plate layout, just a different target printer. It struck me how similar the two prints looked - not just with respect to the VFAs but also with respect to other imperfections such as ringing (which aren't all captured effectively in these photos).
With the two prints in front of me they're almost indistinguishable, and I really don't think that anyone would be able to say which one was printed by which printer. In fact the blue one was printed on my MK4S and the orange one on the CORE One.
I thought this might provide some interesting perspective in this thread bemoaning the VFAs on the CORE One.
At this point I suspect that phase stepping offers the best hope of doing anything about the VFAs (although I note that this hasn't necessarily been the case with the XL), and if they can get it working for the CORE One then is it reasonable to hope they could do the same for the MK4S?
RE: VFA Artifacts on X+Y Straight Edges
Indeed your CORE One seems less affected by belt ripples than others on this thread (including mine). It’s crazy how it seems to be so different between printers, and that shows that I think it won’t be fixed so easily.
I hope my kit that will show next month won’t be so much affected neither.
RE: VFA Artifacts on X+Y Straight Edges
Actually I’d hoped to convey a different message - that the MK4/4S is equally affected, yet I don’t recall many complaints about it when the MK4 first arrived. Maybe my CORE One IS better than average (I’m not convinced) or maybe first-time Prusa buyers have their expectations set a bit higher for the CORE One.
RE: VFA Artifacts on X+Y Straight Edges
I built the DIY Tension Meter because I wanted to know how tight the belts in the Core One are.
They also seem looser to me compared to the MK4.
Printed in Prusament ASA black/orange.
Really nice surface, by the way, absolutely smooth and a perfect fit.
I only mention this because reading this forum you might get the impression that something like this is not possible with the Core One.
The print is simply flawless, like most of what the Core One prints.
MK4S and Core One are set to the recommended frequency.
With the MK4S I measure 2.7 with the Core One 2.2, which corresponds to a value of 5lb and 3lb.
The highest recommended tension for the motor on the Core One is around 3.4lb.
This also depends on the position of the pully on the shaft. The closer it is to the motor, the more tension it can withstand.
Prusa's value is therefore quite suitable and should not be increased significantly in favor of the stepper's service life.
RE: VFA Artifacts on X+Y Straight Edges
Actually I’d hoped to convey a different message - that the MK4/4S is equally affected, yet I don’t recall many complaints about it when the MK4 first arrived. Maybe my CORE One IS better than average (I’m not convinced) or maybe first-time Prusa buyers have their expectations set a bit higher for the CORE One.
If I had your VFAs on my core one, I would not complain. Yours are not bad at all. My MK4s and Core One give completely different results.
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I built the DIY Tension Meter because I wanted to know how tight the belts in the Core One are.
Printed in Prusament ASA black/orange. [...]With the MK4S I measure 2.7 with the Core One 2.2, which corresponds to a value of 5lb and 3lb.
The highest recommended tension for the motor on the Core One is around 3.4lb.
As you printed the meter with ASA instead of PETG, you are probably underestimating the tension a bit. Not a major difference, the elastic modulus of ASA is 10..20% higher than for PETG.
Edit: Oh, by the way -- aren't the motors exactly the same in the Core One and MK4S? So why can the tension be higher in the MK4S? Are Prusa running the motor bearings out of spec there when the printer is set to the recommended belt tension?
RE: VFA Artifacts on X+Y Straight Edges
I did not print the Prusa part but this one.
As with many CoreXYs, the pully on the Core One is relatively far out.
This makes it easier to bend the shaft, which reduces the possible force. On the MK4S, the pullys sit very close to the motor. This allows higher tensioning.
RE: VFA Artifacts on X+Y Straight Edges
I did not print the Prusa part but this one.
As with many CoreXYs, the pully on the Core One is relatively far out.
This makes it easier to bend the shaft, which reduces the possible force. On the MK4S, the pullys sit very close to the motor. This allows higher tensioning.
That's a much nicer meter design, with an actual metal spring where one can verify the spring constant. Thanks for the pointer! And good point regarding the effective shaft length: For the motor which drives the lower belt it is actually quite long, resulting in an unfavorable leverage on the front bearing.
RE: VFA Artifacts on X+Y Straight Edges
I posted it here because some here in the thread are ramping up the tension quite a bit.
I wanted to measure what tension is actually applied.
Just because the Voron use 115hz doesn't mean it's appropriate for the Core One.
The Voron measure at 150mm distance, the Core One at 255mm.
This means that the frequency is lower for the same tension.
RE: VFA Artifacts on X+Y Straight Edges
These belts must be used in industrial machines and environments where the correct tension is of utmost importance…my question is how is the tension of the belts in such machines measured?
I presume they’re not relying on 3d printed gauges or measuring the audio frequency when the belt is plucked?
RE: VFA Artifacts on X+Y Straight Edges
As someone mentioned, they are measured by audio frequency in professional environment too. Just with something better than phone. But the phone is good enough for printers. If the measurement is off, it does not matter as long as both belts has similar tension.
RE: VFA Artifacts on X+Y Straight Edges
Anybody had any luck running the motor phase stepper calibration wizard?
Referenced here - https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4461#issuecomment-2773507889
It seems some have tried and had a memory heap error. We could se it fixed in a future firmware release.
RE: VFA Artifacts on X+Y Straight Edges
We could se it fixed in a future firmware release.
Yes, we could. Maybe, eventually. If and when Prusa finally gets around to it. They have had a few false starts, and have not given further updates for several weeks. I am not holding my breath.
RE: VFA Artifacts on X+Y Straight Edges
Gave it some tries, but got the error every time.
I think they fixed it now, but we'll have to wait for the firmware release.