RE: VFA Artifacts on X+Y Straight Edges
Oh, yes we are talking about those resonance noises. It really bothered me too, I couldn't really have the printer printing in the same room as I was working. Even using stealth mode.
That's a bif relief to me if those noises disappeared! If you now can print and work in the say room, it's a nice thing!
RE: VFA Artifacts on X+Y Straight Edges
Maybe they actually didnt see that amount of VFAs on their testing machines, but as production scaled up some machine got worse due to tolerances in parts and the assembly process that they could not forsee due to being a very small development team. Its a tricky subject when going from lab test mules to full serial production, thats why in the product development world there are alot of building of products out of tooling before stuff are sent out to customers, in this case it seemed like they went directly out to customers in a hurry to get it out on the market. Though to be fair that seems quite common in this business.
I think the production is not a problem. I have assembled unit and VFAs are problem only at specific speeds. The issue may be shipping. Some people got their printer in a great shape. Some received units with bent frame, broken panels, etc. And then there are some in between without any visible damage, but things may be slightly bent and off. Which may pronounce VFAs to extreme levels shown on that video. Not squared XY gantry, which causes faulty homing, is another known issue for some users. I believe Josef that units Prusa has been testing in house prints great. They need to get back faulty units for repair to learn what can go wrong and how to fix it. It's not possible to imagine and simulate all the possible issues in advance.
RE: VFA Artifacts on X+Y Straight Edges
Hey, tldr, some of you might benefit from changing the motor pulleys. But keep in mind it's a lottery, even proper Gates or Mellow pulleys can get a better or worse batch, as I have noticed in my testing. Order as many as you can and swap them on the left motor only as it's much easier to access without dismantling anything. Just loosen the belt tensioner on BOTH sides to keep the gantry square, unscrew the motor, lift it, replace the pulley, put it back in to catch that loose belt loop, screw everything in place, tension. Then print a test for the angle this motor is responsible for (same diagonal as solid infill). Then replace with another pulley until you isolate the 2 best pulleys out of everything you have. Then put them onto both motors (the right one can be accessed without dismantling the belt but it's a big pain). The remaining ripples can be further reduced by grossly overtensioning the belts (we're talking 100Hz and above).
RE:
Hey, tldr, some of you might benefit from changing the motor pulleys. But keep in mind it's a lottery, even proper Gates or Mellow pulleys can get a better or worse batch, as I have noticed in my testing. Order as many as you can and swap them on the left motor only as it's much easier to access without dismantling anything. Just loosen the belt tensioner on BOTH sides to keep the gantry square, unscrew the motor, lift it, replace the pulley, put it back in to catch that loose belt loop, screw everything in place, tension. Then print a test for the angle this motor is responsible for (same diagonal as solid infill). Then replace with another pulley until you isolate the 2 best pulleys out of everything you have. Then put them onto both motors (the right one can be accessed without dismantling the belt but it's a big pain). The remaining ripples can be further reduced by grossly overtensioning the belts (we're talking 100Hz and above).
Seems to show a clear improvement, thanks for this...but I'm not shelling out for new pulleys on a 2 month old machine through principle.
If Prusa concede this is the issue and the pulleys need replacing, they should be sending them out gratis....thats a big 'if' though, they still haven't even properly admitted there is an issue.
This is why communication is key, and this issue (and the way it is handled) will be what I'll be use when I'm considering buying more Prusa machines. If all we hear is tumbleweeds for the next few days/weeks/months then that decision will be practically made for me.
RE: VFA Artifacts on X+Y Straight Edges
Seems to show a clear improvement, thanks for this...but I'm not shelling out for new pulleys on a 2 month old machine through principle.
If Prusa concede this is the issue and the pulleys need replacing, they should be sending them out gratis....thats a big 'if' though, they still haven't even properly admitted there is an issue.
This is why communication is key, and this issue (and the way it is handled) will be what I'll be use when I'm considering buying more Prusa machines. If all we hear is tumbleweeds for the next few days/weeks/months then that decision will be practically made for me.
I agree with you 100%. This whole situation is utterly ridiculous. It made me look at alternatives and, tbh, my next printer will most likely be a Voron with the INDX system instead of a "Prusa Core Two" or whatever else they release. There's only so much I can deal with, I just needed nice quality prints no matter the speed, which this machine fails to deliver. Even my MK3S+ prints better...
RE: VFA Artifacts on X+Y Straight Edges
It would be nice to have some things we could check. Maybe even some simple printable tools to check if things are square. I built mine from a kit but have the same VFA issues everyone else seems to have. I checked to make sure everything was square but mostly that is me eyeballin git as it assembled without issue and moves along the rods at the same time.
Maybe they actually didnt see that amount of VFAs on their testing machines, but as production scaled up some machine got worse due to tolerances in parts and the assembly process that they could not forsee due to being a very small development team. Its a tricky subject when going from lab test mules to full serial production, thats why in the product development world there are alot of building of products out of tooling before stuff are sent out to customers, in this case it seemed like they went directly out to customers in a hurry to get it out on the market. Though to be fair that seems quite common in this business.
I think the production is not a problem. I have assembled unit and VFAs are problem only at specific speeds. The issue may be shipping. Some people got their printer in a great shape. Some received units with bent frame, broken panels, etc. And then there are some in between without any visible damage, but things may be slightly bent and off. Which may pronounce VFAs to extreme levels shown on that video. Not squared XY gantry, which causes faulty homing, is another known issue for some users. I believe Josef that units Prusa has been testing in house prints great. They need to get back faulty units for repair to learn what can go wrong and how to fix it. It's not possible to imagine and simulate all the possible issues in advance.
RE: VFA Artifacts on X+Y Straight Edges
I'm sorry to say that this has caused me to cancel my order. That combined with the fact that I still haven't received my printer from a day 1 order back in November has left me frustrated.
I have been fortunate that I've been able to get by with my business without this printer, but the current lead time on an assembled unit is only 2 weeks. I just asked myself what am I waiting for?
If Prusa fixes the VFA issue then I'll reconsider. With a 2 week lead time I'll not be out much after already waiting 6 months. I keep reaching out to support and they unfortunately are not helpful. More of a sit and wait. They tell me they cannot split my order, that I can only cancel items and reorder others. This puts me back at the end of the line which makes no sense
Im going to try my hand at a more user involved option and buy that Ston Wolf printer. I'm a mechanical engineer and that printer is built more how I would build one. Machined precision plates.
I'm not knocking Prusa. I've had very good luck with my machines. It's just their system for filling orders is broken imo. Everything on my order has been shipped and received by others, so how in the world has my day 1 order not been fulfilled?
RE: VFA Artifacts on X+Y Straight Edges
I'm sorry to say that this has caused me to cancel my order.
[...]
Im going to try my hand at a more user involved option and buy that Ston Wolf printer. I'm a mechanical engineer and that printer is built more how I would build one. Machined precision plates.
Sorry to read about your frustrations and eventual decision, but I can certainly understand it. It seems that Prusa have maneuvered themselves into a perfect storm -- losing their technical leadership in the field, taking shortcuts on quality, and not getting a handle on their fulfilment and support processes. I am still dithering whether or not to keep my Core One.
By all means, please let us know how the Ston Wolf performs! I have been tempted by this printer too, but really need an enclosed unit. (Most of the year it's too chilly in my basement to even print PETG.) Hope the Ston Wolf prints will look as neat as the printer!
RE: VFA Artifacts on X+Y Straight Edges
@jurgen
I'm not bailing on Prusa, just this particular order. I really like the ecosystem, regular updates, continuous improvement etc. I wouldn't hesitate to buy more Prusa printers when my demand increases, because all of my other Prusa printers just work.
I was buying the Core One to do some more specialized printing.
The Ston Wolf doesn't currently have an enclosure, but I'll either do my own or they have one coming out in July. The current lead time is 5-7 weeks so the enclosure should be ready about the same time my printer ships.
RE: VFA Artifacts on X+Y Straight Edges
Today I got a response from Prusa. They want to keep my Core One for further investigate the issue and they want to send me a new one.
Other people might be happy, I'm not. My response was if he's sure that not more, if not all Core One face these issues. I also added that it doesn't make sense for me to get a replacement if the result is the same as of I would keep my first Core One...
RE: VFA Artifacts on X+Y Straight Edges
Today I got a response from Prusa. They want to keep my Core One for further investigate the issue and they want to send me a new one.
Other people might be happy, I'm not. My response was if he's sure that not more, if not all Core One face these issues. I also added that it doesn't make sense for me to get a replacement if the result is the same as of I would keep my first Core One...
If all Core Ones would face the same issue, why would they want specifically yours for investigation? I guess it may take some time to investigate and fix it. Getting a new one now sounds like a good deal.
RE: VFA Artifacts on X+Y Straight Edges
Good question, I don't know. Maybe they keep all printer which come in rn for repairs of the VFA issue...
Today I got a response from Prusa. They want to keep my Core One for further investigate the issue and they want to send me a new one.
Other people might be happy, I'm not. My response was if he's sure that not more, if not all Core One face these issues. I also added that it doesn't make sense for me to get a replacement if the result is the same as of I would keep my first Core One...
If all Core Ones would face the same issue, why would they want specifically yours for investigation? I guess it may take some time to investigate and fix it. Getting a new one now sounds like a good deal.
RE: VFA Artifacts on X+Y Straight Edges
Yeah definitely take the new one, it's a no-brainer.
RE: VFA Artifacts on X+Y Straight Edges
Here's something that might interest you and something others with pronounced VFAs might want to check for. I've printed for 100 hours+ now and I notice the belt is worn on several places and there is a buildup of debris near the motor pulleys or idlers. Anybody else see the same? 
RE: VFA Artifacts on X+Y Straight Edges
Here's something that might interest you and something others with pronounced VFAs might want to check for. I've printed for 100 hours+ now and I notice the belt is worn on several places and there is a buildup of debris near the motor pulleys or idlers. Anybody else see the same?
Thanks for this - I've finally found that screw that I dropped when swapping the top rails around!
No such build-up here (after 6d 4h), but I did notice that there's zero gap between the upper belt and the cable tie that holds the thermistor between the fans. No sign of wear or rubbing at that point on mine, but if the cable tie was fractionally less tight it could interfere with the belt teeth. I doubt that would cause debris where you're seeing it, but it's another potential VFA culprit.
RE: VFA Artifacts on X+Y Straight Edges
Here's something that might interest you and something others with pronounced VFAs might want to check for. I've printed for 100 hours+ now and I notice the belt is worn on several places and there is a buildup of debris near the motor pulleys or idlers. Anybody else see the same?
Mines on 5 days, so around 125 hours, and that area on my printer is spotlessly clean. Somethings wrong on your printer...but I don't think it's related to VFAs.
RE: VFA Artifacts on X+Y Straight Edges
Here's something that might interest you and something others with pronounced VFAs might want to check for. I've printed for 100 hours+ now and I notice the belt is worn on several places and there is a buildup of debris near the motor pulleys or idlers. Anybody else see the same?
Thanks for this - I've finally found that screw that I dropped when swapping the top rails around!
No such build-up here (after 6d 4h), but I did notice that there's zero gap between the upper belt and the cable tie that holds the thermistor between the fans. No sign of wear or rubbing at that point on mine, but if the cable tie was fractionally less tight it could interfere with the belt teeth. I doubt that would cause debris where you're seeing it, but it's another potential VFA culprit.
Yeah I was concerned about that cable tie when I built the kit, but was assured it was correct to be close. I've just checked my cable tie again and after 5 days printing its not worn or marked in any way, so I think its just clearing the belt.
RE: VFA Artifacts on X+Y Straight Edges
Total 3D printing and Prusa noob here.
For real: How bad is the VFA issue and does it concern EVERY Core One? Do you think it might get fixed or is fixable by soft- or hardware?
Are there any alternatives in print quality and quality of the printer with much less VFA?
I ordered mine (Batch 13) with the accelerometer and was hoping that Prusa might adress this „problem“ in the time of waiting for my shipping.
To fix? most will be considerably reduced by printing slower.
If you are going to paint the print they will be completely obscured.
If you are printing a fraction oversized intending to sand the part to an accurate fit they will disappear.
In practice, if you are printing functional parts you will never notice them.
If you print dark coloured matt filament you will have trouble seeing them.
If you were printing prior to the Mk3 you wouldn't have noticed them on your ostensibly perfect print.
If you are too lazy to post process your prints, are obsessed with cosmetics and place every glossy-filament print under a shallow glancing light source with no diffused fill light then you will weep unconsolably.
Cheerio,
RE: VFA Artifacts on X+Y Straight Edges
Total 3D printing and Prusa noob here.
For real: How bad is the VFA issue and does it concern EVERY Core One? Do you think it might get fixed or is fixable by soft- or hardware?
Are there any alternatives in print quality and quality of the printer with much less VFA?
I ordered mine (Batch 13) with the accelerometer and was hoping that Prusa might adress this „problem“ in the time of waiting for my shipping.
I think there is really not much more to say than what you can glean from this long thread.
VFAs are very real, they seem to occur in every Core One. Whether the differences reported between different Core One units are due to parts tolerances, assembly tolerances, obvious assembly flaws (e.g. wrong belt tension), or just people having different levels of sensitivity is still hard to say. Objective comparison between photographs is tricky, due to different filaments and illumination conditions being used.
Since no root cause has been identified, it's also impossible to say to which extent Prusa will be able to alleviate the problem. We have first reports from users who have tried the "calibrated phase stepping" which is inofficially available in the 6.3.3 firmware now -- they seem to observe improvements in acoustic noise but not in VFAs. Jo Prusa has claimed in a Reddit post that "we don't see strong VFAs in-house", but I am not sure whether I believe him. At least Prusa seems to be listening to the customer complaints now and is apparently analysing some printers that have been returned to base.
I have had my Core One kit for nearly two months now and had certainly hoped to see an improvement from Prusa during that time -- to help with my decision whether to keep the printer. The 60-day return window will be closing very soon for me. I guess I'll toss a coin over the weekend...