RE: VFA Artifacts on X+Y Straight Edges
Potential buyers of the Core One will be reading here, and get to read only about problems, not about a single solution from Prusa (or even a path towards a solution) yet. I bet Bambu Labs are reading here and are having a blast...
I concur.
Actually, I was reading a post on this forum from back in 2022 earlier today, and Prusa employee's were actively participating and responding. So it seems it's something that used to happen, but then stopped......
--> MK4 - MK4S - MINI+ - MMU3 - Accelerometer Guide - BambuLab A1 Combo <--
RE:
Just did a test. The distance between artifacts is ~2mm on x/y axis. Depending on the directions, the intensity of belt rippling differs quite a lot.
Prusament PETG, 0.2mm Structural HF Profile 
RE: VFA Artifacts on X+Y Straight Edges
I’m currently trying to solve this same issue on my XL. Would you mind outlining your process of straightening the gantry in a little more detail?
Not about the Core One, but my XL.
After straightening the CoreXY gantry (I used the margin of error on all screws—try this at your own risk), I finally achieved a perfectly aligned X-axis with both belts tensioned to 85Hz.
After dialing in the optimal speed, flow, and temperature settings for PETG, I’m now getting acceptable VFA on perimeters parallel to the X-axis and a really nice finish on one wall parallel to the Y-axis (printing from front to back). However, the second wall still shows VFA on my X- and Y-symmetrical vase. Tomorrow, I’ll contact Prusa support because I suspect one of the steppers might be faulty.
5 kg of PETG and around 100 hours of tinkering and slicer adjustments later, I’m really disappointed with the so-called legendary Prusa quality. I do a lot of tinkering to achieve the best quality—even with Bambu printers—but with Bambu, I’m refining the print to look better than injection-molded parts. With Prusa, I’m just struggling to get anything decent at all. 😅
RE: VFA Artifacts on X+Y Straight Edges
My printer is packed and being sent back to Czechia.
I hope they replace the mechanics or I think I'll probably just ask for a straight refund
RE: VFA Artifacts on X+Y Straight Edges
We were able to find the issue with the printer which was causing the VFA on the print. This was related to the extruder motor which seems to have become faulty. We have replaced the motor and are now running the test prints to make sure that the issue is completely gone. We will do the same print that you sent to us with different filaments to insure that this is addressed, the reason being as some filaments can hide this artifacts pretty well while others, such as blends or silk filaments, due to their glossiness will make this more visible and noticeable. At this point we are optimistic that we are able to have your printer repaired and shipped back to you within the next days
RE: VFA Artifacts on X+Y Straight Edges
The extruder motor? Now that's unexpected. Why would an irregular filament extrusion -- even if it follows a periodic pattern -- cause those exactly vertical stripes, i.e. recur at the exact same XY position in every layer? Seems like a very rare coincidence, unless there is some coupling mechanism between extrusion and XY position which I am unaware of.
Anyway, I am glad to hear that Prusa have looked into this pretty quickly. Fingers crossed that they have fixed the root cause!
RE: VFA Artifacts on X+Y Straight Edges
Yes I will be surprised if the extruder motor would cause such perfect regular artefacts but according to the technical report it seems to be the only thing found faulty.
RE: VFA Artifacts on X+Y Straight Edges
That’s surprising. Maybe the extruder motor was drawing way too much current and causing voltage sag in the other extruders?
RE: VFA Artifacts on X+Y Straight Edges
Well, that's interesting. And it begs the question: how many of us have bad extruder motors? And how hard is it to get ours replaced?
RE: VFA Artifacts on X+Y Straight Edges
Wat. I think you’ve misconstrued.
Well, that's interesting. And it begs the question: how many of us have bad extruder motors? And how hard is it to get ours replaced?
RE: VFA Artifacts on X+Y Straight Edges
That's interesting - I noted with a couple of my prints I was getting them when using the 0.15 Speed profile and not getting them when I used the 0.2 Speed profile.
RE: VFA Artifacts on X+Y Straight Edges
Hmmm.
That was - I think - an issue with the Mk4S also. Wasn't the conclusion there that multitudes of the nozzle diameter sometimes / somehow seemed to work better?
RE: VFA Artifacts on X+Y Straight Edges
We have now conclude the repair of your printer. Indeed the motor was causing some artifacts on the printer and replacing it helped with the issues to some extend. We still have some VFA happening on some particular prints and with this we have checked it with our developers and passed the case to them. They have informed us that what we are having right now is more an issue related to the Firmware and slicer profiles and this will be address on the next releases. The new Firmware for the printer is expected to be released next week.Here we are ready to send the printer to you. Replacing the printer with a new one is not really an option here as this won't solve the issues.
Attached on this email are the test prints results, interesting enough, the slower you print the more noticeable are the VFA on the prints but we can only see that on the print in place box. On our test prints this is not noticeable.
Here we have a few options.return the printer back to you If you do not wish to keep the printer we can refund itLet me know how you want to proceed here.
RE: VFA Artifacts on X+Y Straight Edges
This is upsetting, I am not sure on what to do here. I may take the refund as I don't want to have a very expensive mechanical problem and pray that software fixes it in future.
RE: VFA Artifacts on X+Y Straight Edges
Here are the photos from Prusa Support reproducing the issue after the "repair"
RE: VFA Artifacts on X+Y Straight Edges
Looks to me like the extruder motor diagnosis was a red herring -- I don't see any real change vs. your earlier test prints?
I would ask Prusa support to provide more specific information on the "issue related to the Firmware and slicer profiles", maybe including a link to the respective issues on Github. Maybe it's about enabling the calibration for phase stepping, but I have not seen any updates indicating that this is about to be released for the Core One.
If they can't add more plausibility and detail to the "we will fix it in firmware" claim, I would be inclined to opt for the refund. You can always order a new unit later (or a kit if you prefer), if and when there is more clarity about substantiated VFA improvements.
RE: VFA Artifacts on X+Y Straight Edges
Replacing the printer with a new one is not really an option here as this won't solve the issues.
That bit is disconcerting, by the way. So they claim that this is not an issue of unfortunate tolerances in the motors, belt alignment or wherever, but that all Core One printers produce this level of artifacts at certain printing speeds? 😕
RE: VFA Artifacts on X+Y Straight Edges
Is this the same as the 0.15 vs 0.2 layer height problem.
I know I see them with 0.15 and not 0.2
RE: VFA Artifacts on X+Y Straight Edges
Is this the same as the 0.15 vs 0.2 layer height problem.
I know I see them with 0.15 and not 0.2
Does changing the layer height cause a change in motion speed as a side effect? If the motion speed is limited by the filament extrusion rate, the smaller layer height should allow faster XY speeds. That could plausibly impact the VFA performance.
(I don't believe the direct connection to the extruder motor which Prusa support had postulated in their dialog with @baztm.)
RE: VFA Artifacts on X+Y Straight Edges
Just got my Core 1 on Monday, so I haven't had much time to test it out, but I can see similar artifacts, maybe not as pronounced but it's hard to compare given differences in lighting and shininess of the print. The only thing I have done to the printer is adjust the belt tension as it arrived with one belt around 100 Hz and the other audibly higher but off scale. I printed out an octagon (PLA, 0.2 height, structural profile) so I can see the effect of motion direction. Not much difference between the x and y, but moving at 45° to the axis increase the frequency of the artifacts by 2x which makes sense since one of the steppers will be running at 2x the speed. Like posted earlier the period is around 2mm when traveling along one of the primary axis. I'm interested to try it again with an angle closer to 22° and see if I can see a beat frequency between the two separate drives.
Along the x or y axis (sorry lost track of the orientation)
45° relative to the x or y axis:
I tried to measure the height of the ripple with a feeler gauge. It is certainly less than 10µm peak to valley, but would need a better setup to get a more accurate measurement. I can't really feel the ripple with my finger. Since I print mostly structural prints this isn't really a big issue for me personally but more interested in figuring out the cause.