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
Take that 0.2 Speed profile you used for the one on the left and crank the print temperature up by 20-30C. Bet you a dollar it'll look basically the same.
RE: VFA Artifacts on X+Y Straight Edges
The extruder can absolutely cause VFAs. [...]
The extruder is essentially trying to fill a "pool" or "vat" in the hotend and push it out the nozzle. If that "vat" is getting emptied at a rate faster than it is being filled, and its being emptied and filled at a constant rate (moving in a straight line) then it makes sense that the cyclical nature of being emptied and filled would cause some ripple in the plastic being deposited in the perimeter.
Hmm... I am not sure I understand. Maybe some cyclical process of underfilling and refilling can develop in the extruder and hotend. But why would it always (for different layer heights, XY speeds etc.) be exactly in sync with the XY movement? The extruder "oscillation" would need to be back in the exact same phase every time the print head returns to a certain XY position, to produce the observed vertical VFA stripes. Why would that be the case?
RE: VFA Artifacts on X+Y Straight Edges
Because when you print a perfect square box, its always going to align in those regions where its doing the same movements. When I first figured this out I thought the same thing - theres no way the extruder is doing this when one full revolution of the extruder gear is certainly more than 2mm so why would it be repeatable? But in my own testing and discussion with friends I could absolutely change nothing but bump up EM from say 0.96 to 1.02 and see the VFAs reduce.
I know this is a kind of unsatisfying unscientific answer - and by no means am I trying to say "this is 100% the extruder!" but more so just say that the extruder can play a role in VFAs and Im not exactly surprised to see Prusa comment on it.
RE: VFA Artifacts on X+Y Straight Edges
I can see noticeable VFAs on my Qidi Plus3, Plus 4, Q1 pro, X1, MK4S, and now Core One. My two Voron 2.4s have absolutely none.
I'm interested to see what Prusa follows up with on this.
Same experience here on a Q1 Pro, Mk3S+, and now the Core One. My Voron 0.2 has zero VFAs at any print speed up through some pretty ridiculous ABS profiles, though to get that I had to get rid of the stock Clockwork and its Bondtech BMG-gear dual-hob setup. I replaced it with a Bondtech LGX Lite and since then it's been about as flawless as I can be bothered to make it. Not quite PIF level quality but it's at the 80/20 breakover point in terms of calibration effort for me. 😉
I'm also interested in seeing where this goes as I've read somewhere in here where they fixed a very similar (maybe the same) issue with motor tuning on the XL a while back. Hopefully, they'll have the same success with the CoreOne as they did with the XL.
RE: VFA Artifacts on X+Y Straight Edges
Because when you print a perfect square box, its always going to align in those regions where its doing the same movements.
But VFAs will still be vertical even if the walls you print are not, e.g. if the box is not square. Say you print a box where two opposing walls are not vertical but tilted inwards, and hence the other walls have a parallelogram or trapezoidal shape, with the corner positions shifting layer by layer -- the VFA structures on those trapezoidal walls will still be vertical.
The VFA phase does not depend on where filament was extruded, and doesn't even depend on the movement path the print head took -- but only on its absolute XY position. I can't see how the extruder/hotend could be "aware" of this position and always be in the same state for a given XY position of the print head.
RE: VFA Artifacts on X+Y Straight Edges
Posted by: @butter-pockets
I can see noticeable VFAs on my Qidi Plus3, Plus 4, Q1 pro, X1, MK4S, and now Core One. My two Voron 2.4s have absolutely none.
I'm interested to see what Prusa follows up with on this.
Same experience here on a Q1 Pro, Mk3S+, and now the Core One. My Voron 0.2 has zero VFAs at any print speed
Don't the typical Voron builds use toothed idlers where the toothed side of the belt is running over an idler? (And smooth idlers or bearings where they touch the smooth side of the belt?)
Running toothed belts over smooth idlers is often suspected to be a cause of VFAs. Although there is debate around this, with some people claiming that it's not an issue as long as the belt tension is optimal. (And the belt teeth don't strongly brush against any idler flanges, of course.)
RE: VFA Artifacts on X+Y Straight Edges
its not that its aware, its not relative to the print direction. I just mean when you print a vertically flat surface, all the perimeters at all the heights will be printed at the same speeds and feeds. Which means the extruder is feeding the hotend the same way each time. The actual like tooth on the gear in the extruder doesnt need to align. You could say the same thing about the idlers and motors. Depending on what happens between those straight sections of the print the idler, belt, motor, etc won't always be aligned to where they were on the previous layer, but they will be moving the same way.
RE: VFA Artifacts on X+Y Straight Edges
Yes, vorons do use toothed idlers on toothed side of the belt and smooth idlers on smooth side of the belt. This was something Ive been wondering and this thread has provided a bit of insight into this. Doesnt seem to affect things as much as I thought it would.
RE:
its not that its aware, its not relative to the print direction. I just mean when you print a vertically flat surface, all the perimeters at all the heights will be printed at the same speeds and feeds. Which means the extruder is feeding the hotend the same way each time. The actual like tooth on the gear in the extruder doesnt need to align. You could say the same thing about the idlers and motors. Depending on what happens between those straight sections of the print the idler, belt, motor, etc won't always be aligned to where they were on the previous layer, but they will be moving the same way.
I realized I didn't address exactly what you said, but it won't let me edit it. Regardless if its vertical or not, the speeds and feeds should be the same. Which means the extruder is doing the same thing at that time, even if the surface isn't vertical. The oscillation can be coming from the motion system itself, but I don't think we can rule out the system pushing the plastic either. It will be in phase with the layer below it because its doing the same move, regardless if its perfectly vertical or not. Like I said, this isn't a satisfying answer, but it seems to make intuitive sense to me that the extruder/hotend can cause an oscillation in the plastic being pushed out.
RE: VFA Artifacts on X+Y Straight Edges
I can see noticeable VFAs on my Qidi Plus3, Plus 4, Q1 pro, X1, MK4S, and now Core One. My two Voron 2.4s have absolutely none.
Interesting, all your commercial printers have more or less VFA.
Were your Vorons like this from the start, or do you attribute it to your settings?
When I look at the cross-manufacturer cause of VFA, which has been discussed for years, dynamic processes must be involved. There doesn't seem to be a simple solution.
It doesn't seem to depend on one parameter. Someone replaces the pulleys and the VFA disappears. He feels vindicated and is convinced that he has found the solution.
But on another printer, this change may not work at all.So there can't be just one solution, as nice as that would be.
Last time I saw a YouTube video with a high-speed film of the printer, which was very interesting. Belt vibrations, extrusion at the nozzle or micro-stepping provide completely new insights.
The dynamic pressure conditions in the hotend should also not be ignored. There are indications that the VFA will also disappear if the settings that influence this are changed.
The changes in speed also result in changed pressure conditions in the hotend. Sometimes different factors may add up unfavorably. If a parameter is then changed, an improvement occurs.
Any process stabilization, mechanical, electronic or via slicer parameters will prevent this risk and improve the print quality.
You can only try to set up the printer in the best possible way to minimize mechanical causes. Maybe that's why the Vorons work so well.
Anyone who has worked in production knows how different the results can be. There are so many parameters. And even there they can add up unfavorably.
RE: VFA Artifacts on X+Y Straight Edges
Interesting, all your commercial printers have more or less VFA.
Well, not all of them. My A1 and Neptune 4 pro dont.
Were your Vorons like this from the start, or do you attribute it to your settings?
I never had any issues with it
The dynamic pressure conditions in the hotend should also not be ignored. There are indications that the VFA will also disappear if the settings that influence this are changed.
This is basically what Im trying to say. I truly don't know if I can explain the hows and whys, but the pressure in the hotend really can contribute to this.
RE: VFA Artifacts on X+Y Straight Edges
I'm convinced it's due to the motors - mechanically the system is very rigid which is good but it is showing up these inconsistencies in the motors at certain speeds.
Again I've seen someone have the same problem when running string instead of a toothed belt!
I think most other manufacturers probably mask the problem by preventing moves at the offending speeds, printing faster seems to hide it but it also prints the filament more matte which just makes it less visible. At its worst you can definitely feel the pattern!!
Prusa support have told me the same thing:
I would just like to emphasise that the printer only produces the VFA when printing slower, meaning that on the box prints that took 1h the issue is not there, versus with the print that takes 2 hours, and this is most noticeable with the silk filaments ( which are more prone to show these artifacts due to the glossiness.
I wouldn't be surprised if their updates just hides the problem by forcing it to print faster and avoid the "bad" speeds.
RE: VFA Artifacts on X+Y Straight Edges
I wouldn't be surprised if their updates just hides the problem by forcing it to print faster and avoid the "bad" speeds.
That's what Bambulab did. I mean there were no speeds below 150mm.
Interestingly, the A1 from Butter Pockets has no VFA while the top model X1C does.I don't have a personal comparison but I have often heard that the Bambulab Bed Slinger prints more beautifully than the CoreXY.
RE:
My X1C gives me absolutely perfect prints at 50mm/s external perimeters, without any VFA at this speed. I did VFA test and it indeed showed VFA between 60 and 100mm/s, but no VFA under 60 and above 100.
In comparison, my CORE One shows VFA at ALL speeds and makes bothering resonance noises at 40mm/s and 80mm/s (on plain X and Y axis, so at different speeds when printing at angle).
I hate printing at a speed that shows plastic isn't melted properly (matte finish) because it always end by having different shininess on the finish print.
EDIT: what bothers me the most is that it seems forbidden to compare Prusa printers and Bambu Lab ones. I'm sorry but as much I love Prusa, for now my X1C gives better prints and is more silent than my CORE One. I reaaly hope next updates will improve those resonance noises (it really drives me crazy) and VFA.
RE:
Couldn't the extruder fluid resonance theory be tested by printing a shape with a long taper along the corner preceding the flat face? The dynamics of any fluid oscillation should be affected by the turn in direction, and since that corner is happening along a progressively changing location, the initiation of VFA shouldn't align. I suspect we already have small versions of this test in folk's random design that can point either toward or away from the extruder being involved.
I won't be back home for a few days to check my Mk4S printer, but if it has been producing similar VFAs it certainly hasn't risen to the level of me noticing or being bothered by it. Pretty much all I print are functional parts, so pristine surface finish is less critical than dimensional accuracy and consistency.
-J
RE: VFA Artifacts on X+Y Straight Edges
...I am watching this thread while I await my eventual delivery of a conversion kit.
Also, with regard to the pulley alignment theory, has anyone (in this forum or the X1C discussion) tried pulleys that have a taper on the wall, so that misalignment wouldn't result in potentially catching on the sharp side corner as the toothed side of the belt engages and disengages? I'm curious to know if that could help reduce the effects of slight contact along one side of the pulley.
-J
RE: VFA Artifacts on X+Y Straight Edges
EDIT: what bothers me the most is that it seems forbidden to compare Prusa printers and Bambu Lab ones. I'm sorry but as much I love Prusa, for now my X1C gives better prints and is more silent than my CORE One. I reaaly hope next updates will improve those resonance noises (it really drives me crazy) and VFA.
Of course you can and must compare Bambulab with Prusa.
I wrote that I have no personal comparison.
But not all printers are the same.
There are Babulab printers with VFA and Core One without. Only if it's nice for you that your Babulab doesn't have a VFA, there are many in forums that do, for whatever reason.
If we really knew, and the manufacturers too, where it comes from, the issue would have long ceased to exist.
If I take Butter Pockets as an example 10 printers from different manufacturers 6 of them with VFA.
Seems to be a cross-manufacturer problem.
RE: VFA Artifacts on X+Y Straight Edges
Yes I think it is indeed a CoreXY specific issue that is offset by mitigations in software. Plenty cases of this with Bambu X1C too.
That being said I don't understand how vorons seem to be avoiding it!
RE:
I've been researching the issue of resonances and VFAs and came across an interesting system used by the RatRig V-Core 4.0 printer. This printer includes a real-time resonance analysis system that automatically adjusts print parameters during the printing process, significantly reducing these types of artifacts.
This might be an effective solution for the Prusa Core One as well. It would be interesting if the Prusa team considered implementing similar functionality in future firmware updates.
Here's the link for those who want to explore it further: Rat Rig V-Core 4.0 (All Sizes) - Pre-configured kit
I hope this can help us find a definitive solution to the problem.
RE: VFA Artifacts on X+Y Straight Edges
Couldn't the extruder fluid resonance theory be tested by printing a shape with a long taper along the corner preceding the flat face? The dynamics of any fluid oscillation should be affected by the turn in direction, and since that corner is happening along a progressively changing location, the initiation of VFA shouldn't align. I suspect we already have small versions of this test in folk's random design that can point either toward or away from the extruder being involved.
Yes, that's what I tried to describe above when I mentioned printed walls having a parallelogram or trapezoidal shape, due to the adjacent wall being tilted. It still does not make sense to me why in such a geometry extruder-induced oscillations should recur at the same absolute XY position at every Z plane, producing exactly vertical artifacts.