RE: Ringing/ Ghosting pattern all over my prints :/
I also have done the same hardware changes/test as you - with the same conclusions.
Try to test accelerations from 100mm/s2, in my case that helps to achieve supermicro orange peel structure / no structure (depends on shape) which could be compared with bambu quality.
Although I use 1.0 nozzle and 20-30mm/s speeds, so steppers run really quiet + huge layer volumes damps some vibrstions (in my theory).
Greasing the linear guides makes the printer quieter, but does not help to reduce the VFAs.Replacing the belts doesn't really help either.I have also tested various pulley models without success.
During my research I came across an interesting website. https://prorifi3d.com/pages/technical-details The VFA problem seems to be a fairly old problem in 3D printing. After many attempts, my observations match prorifi3d's theory. The main cause is most likely the motor resonances and an irregular force distribution of the stepper motors. Since the VFAs change with the motor speed, it may help to optimize the speed of the outer lines. However, this only helps to a limited extent with a printer like the XL, because depending on the printing angle, one motor turns faster and one slower, and the VFAs reappear. I have just ordered a replacement motor from Prusa for further testing. This now appears to be a new model. It is significantly quieter, but also produces VFAs, albeit with a different resonance behavior than the old motor. The Orca-Slicer VFA test shows a clearly different pattern with the other motor model, but unfortunately not optimal results either. I'm now pretty sure where I need to look for a solution. However, motor optimization should be a big challenge.
Maybe also interesting for further ideas to minimize the VFAs: https://www.automate.org/motion-control/tech-papers/solutions-to-reduce-stepper-motor-resonance
I'll try to print the motor mounts out of hard TPU. Maybe that will help to reduce the resonances.
RE:
I also have VFAs on my XL, but they are much less pronounced and only visible if you look for them. Sometimes they appear only after sharp 90° corners and then fade off. It could be ringing as well, but the spacing is roughly 2 mm and they dont look like the usual ringing patterns so I am suspecting the belts.
I had the following idea, but I haven't had time to test it yet: The VFAs are strongly pronounced on some printers, while other printers print a perfect surface finish. Looking at the motion equations X = 1/2 (A + B) and Y = 1/2 (A - B) and assuming that the toolhead only moves in X direction, both motors must turn at the same rotational speed.
What if, on some printers, the two belts are aligned in such a way, that the gripping of the belt by the two motor pulleys is synchronized, while on other printers the gripping of the two pulleys is offset by half a tooth, so that the gripping effects cancel each other out. The solution would be to loosen one belt and offset it by about half a tooth.
Please let me know if my theory could be right or is complete nonsense.
RE: Ringing/ Ghosting pattern all over my prints :/
I have new idea, changing 20t stepper pulleys to smaller or bigger + changing setup via pronterface.
If the problem is in the stepper, changing RPM in the same speed can provide better results.
Updates soon.
RE: Ringing/ Ghosting pattern all over my prints :/
Nice, XL doesn’t use new M92 values for other pulleys, so can’t check it. I created the bug report on Github:
https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4675
I have new idea, changing 20t stepper pulleys to smaller or bigger + changing setup via pronterface.
If the problem is in the stepper, changing RPM in the same speed can provide better results.
Updates soon.
RE: Ringing/ Ghosting pattern all over my prints :/
Josef Prusa just posted a long explanation about the same kind of issues that seem to occur on the Core One: https://old.reddit.com/r/prusa3d/comments/1lf9mjv/psa_lets_address_the_vfa/
Prusa is apparently working on the issue now, I just hope, they don’t forget the XL.
RE: Ringing/ Ghosting pattern all over my prints :/
Hello - I am trying to convince myself to buy an XL. I can't bring myself to buy Bamboo Lab printer with all of the issues involved. I Am very concerned about the issues that the XL still has after the time it has been out. Wolfy seems to offer some hope for the solving the artifacts on page 2 of the thread. Has anyone else tried to mimic his results?
RE: Ringing/ Ghosting pattern all over my prints :/
Quick update for anyone still following along:
Printed Solid has had my XL for a little over a month now and, unfortunately, they still haven’t been able to resolve the issue. According to the person I’ve been interfacing with, this is the first time they’ve been unable to fix a printer they’ve received, so whatever’s going on with mine is definitely not typical.
They’ve now requested a complete new CORE XY assembly from Prusa to replace the one currently in my machine.
Fingers crossed I’ll have more news in the next week or two.
RE: Ringing/ Ghosting pattern all over my prints :/
Any update on the VFA's? I just built my XL over the weekend and it also has the ringing defects 🙁
RE: Ringing/ Ghosting pattern all over my prints :/
At this point, I’m still waiting for Prusa to make a move.
Since my last update, the technician at Printed Solid informed me that Prusa had decided not to send a replacement CoreXY assembly and instead wanted me to wait several more weeks for a firmware update to see if that resolves the issue. After drafting a message expressing that, after 8 weeks of repair time (which is already twice what’s promised in the warranty policy), this resolution was unacceptable, they’ve now pivoted back to sending a replacement CoreXY assembly.
I was told that if that doesn’t fix the issue, I’d be receiving a full replacement printer.
The most recent update I received was over a week ago, and it’s been radio silence ever since. If I don’t hear back by the end of today, I guess I’ll be writing yet another follow-up email.
It’s certainly been a frustrating experience, to say the least.