RE: VFA Artifacts on X+Y Straight Edges
I'm experiencing these artifacts on my MK4S as well. I was hoping this would be solved when upgrading to Core One... At this point, I have two questions: Does this happen on all Prusa MK4S and Core One printers? Or is this just a limitation of this technology?
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.
Yep this is the same artifacts I am witnessing just less pronounced. Even down to the 45 degrees double frequency. Thank you for printing this, it is very useful representation
I have told them to keep the printer until the new firmware is released and test it. Supposedly next week they can test it. They offered to ship it back to me and wait for the firmware with an option for a refund later but obviously this includes shipping back and forth.
RE: VFA Artifacts on X+Y Straight Edges
My guess on this is that the belt is absolutely not centered on the idlers. Mine showed VFA as well and I saw that belts were not centered and must rub against each idlers.
I don’t know if there is a way to center them more.
But, regarding the response of Prusa after repair, they didn’t change anything, or they think this is a perfectly good print quality. Which is not to me.
RE: VFA Artifacts on X+Y Straight Edges
If you slow the print down on the printer to say 50% with everything else being equal what is the result?
RE: VFA Artifacts on X+Y Straight Edges
If it’s the same as mine nothing will be different regarding VFA. I did a VFA test and it showed those marks at every speed.
RE: VFA Artifacts on X+Y Straight Edges
If you slow the print down on the printer to say 50% with everything else being equal what is the result?
That is why we tried both speed and structural profiles. Same exact VFAs, one is shinier.
RE: VFA Artifacts on X+Y Straight Edges
I was thinking if you slow it down on the printer while printing. Really slow. And they still exist it’s a micro mechanical movement from within the system.
If they change with speed then it’s vibration / resonance related.
If they change with slicing profiles well it probably can be cured by altering slicer profiles.
I’m fascinated that they are so small you can’t feel them. But they are visually very visible with shiny filaments.
I personally for years now changed filaments to find the best finish as I consider 3d printing to be for fun and prototyping. Having said that I’ve produced stunning looking prints with glitter and ‘marble’ filaments, which hide these sort of imperfections. It’s no coincidence that Prusas top sellers are glitter based!
RE: VFA Artifacts on X+Y Straight Edges
This model as been printed with Prusament Galaxy PETG, the top one with CORE One and the bottom one with X1C.
It's even more visible in real life as when you're moving the VFA appears on all the side of the print.
RE: VFA Artifacts on X+Y Straight Edges
Can you upload the STL?
RE: VFA Artifacts on X+Y Straight Edges
Artifacts on curves can be 3D modelling artifacts or slicing artifacts as models and gcode often uses many small polygons by default instead of perfect curves
VFAs on flat surfaces is more of a smoking gun
RE: VFA Artifacts on X+Y Straight Edges
Can you upload the STL?
I already uploaded it here.
Artifacts on curves can be 3D modelling artifacts or slicing artifacts as models and gcode often uses many small polygons by default instead of perfect curves
VFAs on flat surfaces is more of a smoking gun
The file was a step file so in theory no faces.
But here is the result of my VFA test on different speeds:
RE: VFA Artifacts on X+Y Straight Edges
I thought I’d look back over the past weeks prints
I've never noticed the VFAs, they’re not that noticeable and difficult to photograph
what’s interesting is that it appears on the same model with the same filament but disappears with a different slicer profile
RE: VFA Artifacts on X+Y Straight Edges
It seems that your printer isn't as affected as mine.
What profiles did you use?
My printer is going back to repair to Prusa next week, but regarding what they told to another member of this forum, I think I will get a refund and buy a kit so I will make under control every step/alignement. I may also change Y bearings to Misumi, and if I judge X axis rail bad, I will also change it to a better brand.
RE: VFA Artifacts on X+Y Straight Edges
I’ve been using the standard 0.15 speed and structural and 0.2 speed and structural.
because I didn’t notice any differences on print quality I’d opted for 0.2 speed as my default go to.
unfortunately with those I photographed above I don’t know which is which. But what’s is definitely true is I have models that exhibit zero VFAs purely because of the slicing profile that was used.
I will report back when I figure out which on!
it’s the slicing profile that’s results in the filament being more matt finish.
RE: VFA Artifacts on X+Y Straight Edges
More mat finish print is often caused by lack of eating (filament isn't melted properly), so I bet it's speed profile.
When printing with speed profile I always slow down external perimeter to 50-60mm/s to get consistent color/shininess along all the print.
RE:
It seems that your printer isn't as affected as mine.
What profiles did you use?
My printer is going back to repair to Prusa next week, but regarding what they told to another member of this forum, I think I will get a refund and buy a kit so I will make under control every step/alignement. I may also change Y bearings to Misumi, and if I judge X axis rail bad, I will also change it to a better brand.
If they used the same linear rails as the XL they are made by THK. They don't get any better than that. The only thing you could improve is by going to a THK caged linear rail.
Also very unlikely that the bearings have anything to do with it. It's most likely the motor tuning. Being stepper motors the actual steps of the motor can cause VFA's, and the belt can affect it too.
RE: VFA Artifacts on X+Y Straight Edges
Given the 2 mm pitch of the VFAs, it seems very likely that they are related to the belt teeth. Whether it's the belt running off-center and touching the rim of an idler wheel, or the toothed side of the belt running over smooth idlers -- people have proposed different theories and reported success (or lack thereof) after tackling different aspects.
Maybe a rough motor operation, due to uncorrected asymmetries of the windings or such, can contribute to making that belt pitch more visible by "rubbing it in" or inducing micro-vibrations? I don't have a mental picture how that would be connected, but apparently introducing phase stepping calibration has reduced VFAs on some XL printer units which were strongly affected by them.
RE: VFA Artifacts on X+Y Straight Edges
I thought I’d look back over the past weeks prints
I've never noticed the VFAs, they’re not that noticeable and difficult to photograph
what’s interesting is that it appears on the same model with the same filament but disappears with a different slicer profile
Glitter or matte filaments hide those. Try dark petg and you'll see them in the worst way. I've always thought this as belt ripple.
RE: VFA Artifacts on X+Y Straight Edges
Here’s an example of the 0.2 Speed profile on the left with No artefacts and an overall much nicer print
On the right is the 0.15 Structural profile with the VFAs and even the top surface is rough to the touch and shows many artifacts
