RE: VFA Artifacts on X+Y Straight Edges
What do you think? Maybe this issue is really caused by belts..
https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4557#issuecomment-2766762271
It is caused by belts. But may be pronounced by other things. That's why some people experience extreme VFAs, like OP here, and other people barely see them, only when they met very specific conditions. Phase stepping may help some users reduce VFAs. But at least it should reduce the noise of the motors.
RE:
If we check the answer of one of the dev, we should not expect much on phase stepping calibration :
I would start by waiting for actual release 😄 sources are out, binaries are not. We don't expect folks to routinely build and flash their own firmware.
Other than that, OOMs are fixed, calibration has been tweaked, but it still sometimes fails to find correction to motor currents. Maybe because motors are already good, maybe because calibration process needs more tweaks. We don't know yet. I would say code is definitely more stable than in the previous release. Instructions to bypass hidden menu are still the same. We still don't encourage regular people to try it and if they do, they should understand we don't consider this the final version (otherwise we wouldn't be hiding it from the menu).
Also, folks should really manage their expectations about the impact on sound levels and print quality. These issues can be also caused by hardware and if they are, firmware might not be able to fix them. Phase-stepping in particular just corrects the non-linearity of the motors.
Answer's link: Github
RE: VFA Artifacts on X+Y Straight Edges
Can someone answer a question about the toothed idlers? Do the teeth on the belt reach the bottom of the corresponding gaps in the idler, or are the idler gaps deeper than the belt teeth? Unless the idler gaps are deeper, the belt will still alternate between riding on the tip of a belt tooth and the flat of a belt gap. Same question for the toothed pulleys. I would hope that the objective of the toothed pulleys and idlers is always to have the belt riding on the flat of the belt, with the belt teeth only being driven sideways. I'd make a drawing to explain, but hopefully the description is clear.
RE: VFA Artifacts on X+Y Straight Edges
During pure Y-axis movement, the idlers that engage the toothed side of the belt do not move. Yet, VFAs (Vertical Fine Artifacts) still occur on the Y-axis. Therefore, I conclude that simply installing toothed idlers will not resolve VFAs.
In my opinion, motor movement control itself may contribute to VFAs. At the motor, it must “fight” tooth by tooth, and the mechanical response of the system varies depending on the alignment between the belt teeth and the motor pulley. If the motor control is not finely tuned to maintain constant velocity regardless of the required torque, it may cause oscillations in the belt—with a period of 2 mm.
In any case, I’d appreciate hearing from Prusa on this topic.
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Can someone answer a question about the toothed idlers? Do the teeth on the belt reach the bottom of the corresponding gaps in the idler, or are the idler gaps deeper than the belt teeth? Unless the idler gaps are deeper, the belt will still alternate between riding on the tip of a belt tooth and the flat of a belt gap. Same question for the toothed pulleys. I would hope that the objective of the toothed pulleys and idlers is always to have the belt riding on the flat of the belt, with the belt teeth only being driven sideways. I'd make a drawing to explain, but hopefully the description is clear.
I am not sure whether Gates publish detailed design drawings of their belt and idler profiles. But I am inclined to assume that they employ engineers who know what they are doing. They have had a bit more than a century to figure it out. 😉
RE:
Can someone answer a question about the toothed idlers? Do the teeth on the belt reach the bottom of the corresponding gaps in the idler, or are the idler gaps deeper than the belt teeth? Unless the idler gaps are deeper, the belt will still alternate between riding on the tip of a belt tooth and the flat of a belt gap. Same question for the toothed pulleys. I would hope that the objective of the toothed pulleys and idlers is always to have the belt riding on the flat of the belt, with the belt teeth only being driven sideways. I'd make a drawing to explain, but hopefully the description is clear.
Maybe send an email to gates. Unfortunately I don't have anything small enough to measure the depth of the teeth on the idler.
In my mind though they would be deeper than the teeth on the belt or what would be the purpose of them? They are free spinning so if we're still riding on the top of the tooth on the the belt with a toothed idler than what would be the purpose of them? It would be no different then the smooth pulley.
I don't doubt the belt itself is contributing to VFA's, I just don't think it's the teeth running over the smooth pulley that's the main culprit.
Another factor that has been completely overlooked in my opinion is the extruder itself. One of the things that Dr. Tao from Bamboo mentioned in his interview with CNC kitchen was that the reason they use a servo motor on the extruder instead of a stepper had to do with print quality. A servo is a continuous motion motor that uses an encoder for position, so the motor is not stepping, therefore producing a smoother extrusion.
I can upload the file for the core xy parts of sometime else wants to try it out. Just be warned that I have not tested the part myself yet and therefore can't verify it's functionality. It also looks like a decent amount of work to change the parts because of the fact that you have to remove the Nextruder to remove the belts.
RE: VFA Artifacts on X+Y Straight Edges
Another factor that has been completely overlooked in my opinion is the extruder itself. One of the things that Dr. Tao from Bamboo mentioned in his interview with CNC kitchen was that the reason they use a servo motor on the extruder instead of a stepper had to do with print quality. A servo is a continuous motion motor that uses an encoder for position, so the motor is not stepping, therefore producing a smoother extrusion.
There may be some impact of the extruder motor on print quality -- or maybe the servo motor is largely a marketing gimmick from Bambu, like (in my opinion) the Lidar sensor. In any case, I don't see how the extruder could cause the typical VFA/belt ripple signature where the patterns repeat, in phase, in every layer. How would the extruder "know" the current X/Y position, to repeat whatever it did in the prior layer just in the same location?
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This is a fair point, however the extruder motor is directly tied to all printer movements as it needs to extrude an exact amount of filament exactly tied with the movements of the print head.
I have seen up close photos of VFA's and it's essentially an undulation of the extrusion causing reoccurring "blobs" of filament at a very small scale. This could be caused by a number of things, one is the belt where unsmooth movement of the belt is essentially causing the print head to undulate, therefore causing the "blobs" as the unsmooth movement of the print head would cause slightly more/less plastic to be extruded in the areas where the undulation is occurring.
However you could produce the exact same thing if the extrusion of the plastic is not perfectly consistent. Imagine the way a piston engine works. While the movement of the crankshaft seems smooth, of you were to monitor it at a small scale you'd see that the output is actually pulsed and not smooth. The same thing can be said about a stepper motor as it's movement is actually the rotor stepping between poles on the motor.
All of this being said I'm not saying the extruder is the issue, I'm just pointing out that the belts and pulleys are not the only factor here. Maybe in some perfect world you could alter the speed of the extrusion to be in time with the resonances of the belt. Maybe this is the magic Bamboo is doing with their servo extruder. Just theory's here.
I hope Prusa can improve it, but in all honestly if it prints as good as my XL I'll be happy. I was looking at some larger prints I did the other day and they look good. Are there VFA's...... Yes, but are we being overly picky? In my case probably yes, but I didn't think mine are that bad.
This was printed with shiny black PETG.
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If you want to scrutinize the quality of the part more here was a video I did on the part. The video was not at all related to VFA, but you can see the part from different angles.
RE: VFA Artifacts on X+Y Straight Edges
There may be some impact of the extruder motor on print quality -- or maybe the servo motor is largely a marketing gimmick from Bambu, like (in my opinion) the Lidar sensor.
Full agreement. They probably did it more for weight reasons to keep the head still tolerably heavy.The lidar was only available in the X1C, no later printer has it.That says a lot about its usefulness.
In my opinion, you also have to consider the gear ratio of the Nextruder. The motor has much less influence on the extrusion.In a video on YouTube, the difference between normal and Nextruder is shown impressively in slow motion.
RE: VFA Artifacts on X+Y Straight Edges
This is a fair point, however the extruder motor is directly tied to all printer movements as it needs to extrude an exact amount of filament exactly tied with the movements of the print head.
I have seen up close photos of VFA's and it's essentially an undulation of the extrusion causing reoccurring "blobs" of filament at a very small scale. This could be caused by a number of things, one is the belt where unsmooth movement of the belt is essentially causing the print head to undulate, therefore causing the "blobs" as the unsmooth movement of the print head would cause slightly more/less plastic to be extruded in the areas where the undulation is occurring.
However you could produce the exact same thing if the extrusion of the plastic is not perfectly consistent. Imagine the way a piston engine works. While the movement of the crankshaft seems smooth, of you were to monitor it at a small scale you'd see that the output is actually pulsed and not smooth. The same thing can be said about a stepper motor as it's movement is actually the rotor stepping between poles on the motor.
All of this being said I'm not saying the extruder is the issue, I'm just pointing out that the belts and pulleys are not the only factor here. Maybe in some perfect world you could alter the speed of the extrusion to be in time with the resonances of the belt. Maybe this is the magic Bamboo is doing with their servo extruder. Just theory's here.
Bambu is not doing any magic with their servo extruder. H2D has VFAs similar to Core One.
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Bambu is not doing any magic with their servo extruder. H2D has VFAs similar to Core One.
I've seen that thread. You are correct, however it's definitely improved. Better than a Core one..., well I can't compare because I need to see parts side by side.
I can only go off of reviews, and I don't plan on buying any bamboo machines so I'll not be able to do any comparison myself.
Check here at 9:23 on this video from CNC kitchen. He specifically says no VFA'S. Is it the filament he used, his machine, I don't know, but admittedly that part looks really good.
I'm not saying they are doing any magic, or that it's any better, but my logic still holds true. A servo motor works differently then a stepper exactly how I've explained. Is it causing VFA's.... I can't say, however I don't think you can rule out that it could have an influence. It's possible that it's not just the belts, it could be a combination of things.
RE: VFA Artifacts on X+Y Straight Edges
However you could produce the exact same thing if the extrusion of the plastic is not perfectly consistent. Imagine the way a piston engine works. While the movement of the crankshaft seems smooth, of you were to monitor it at a small scale you'd see that the output is actually pulsed and not smooth. The same thing can be said about a stepper motor as it's movement is actually the rotor stepping between poles on the motor.
This is something I had initially considered but for the modulation to be in phase at every layer than the total extrusion per layer would have to be an integer number of whatever modulation in the extruder is causing the artifact. I would think that in most prints that would be unlikely.
RE: VFA Artifacts on X+Y Straight Edges
Here's the revised gantry mount with the pulleys for anyone interested.
RE:
Can someone answer a question about the toothed idlers? Do the teeth on the belt reach the bottom of the corresponding gaps in the idler, or are the idler gaps deeper than the belt teeth? Unless the idler gaps are deeper, the belt will still alternate between riding on the tip of a belt tooth and the flat of a belt gap. Same question for the toothed pulleys. I would hope that the objective of the toothed pulleys and idlers is always to have the belt riding on the flat of the belt, with the belt teeth only being driven sideways. I'd make a drawing to explain, but hopefully the description is clear.
If you use genuine Gates GT2 belts with genuine Gates GT2 idlers, they will match up closely enough for that to not be an issue. The spec is pretty well known at this point, so it's down to manufacturing tolerances. See also the text blurb here ( https://www.filastruder.com/products/gates-2gt-idler?variant=15443755728967) that adds a bit of detail on use.
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Bambu is not doing any magic with their servo extruder. H2D has VFAs similar to Core One.
Interesting. Apparently there is variability among H2D printers as well.
That blue shelf part printed in PETG at 19:55 looks pretty perfect to me from what I can see in the video.
RE: VFA Artifacts on X+Y Straight Edges
Bambu is not doing any magic with their servo extruder. H2D has VFAs similar to Core One.
I've seen that thread. You are correct, however it's definitely improved. Better than a Core one..., well I can't compare because I need to see parts side by side.
It's different than Core One because it's mechanically different machine. But at least from the photos it does not look significantly better than Core One VFA tests. At least not better than mine.
That blue shelf part printed in PETG at 19:55 looks pretty perfect to me from what I can see in the video.
He says it's from PETG HF. I assume that it means Bambu PETG HF, which has matte surface finish. Matte filament effectively hides VFAs and other surface imperfections.
RE: VFA Artifacts on X+Y Straight Edges
If the extruder motor was playing a part in VFAs on the C1 then wouldn’t we see the same issue on the MK4S?
RE: VFA Artifacts on X+Y Straight Edges
If the extruder motor was playing a part in VFAs on the C1 then wouldn’t we see the same issue on the MK4S?
It's probably not the extruder, however it could contribute. There are plenty of posts of people complaining of VFA's on their MK4. Mine prints amazing, but I guess some people's don't.
RE: VFA Artifacts on X+Y Straight Edges
My MK4S had more artifacts (VFA or belts) than my MK4 before, but less than my CORE One. Hope my CORE One kits that will be delivered in a month will be better than my preassembled…
If the extruder motor was playing a part in VFAs on the C1 then wouldn’t we see the same issue on the MK4S?
It's probably not the extruder, however it could contribute. There are plenty of posts of people complaining of VFA's on their MK4. Mine prints amazing, but I guess some people's don't.