RE: VFA Artifacts on X+Y Straight Edges
Yep at the very beginning. I also aligned the gantry according to the video from Prusa. The gantry is with loosen belts with zero gap in the front.
Do you have the exact same number of teeth pulled through the Nextruder carriage for both belts and both sides?
Maybe try again. I have already seen examples where both the squareness of the gantry and the belt tension is equal with the new tuning method. Might be some user error somewhere.
The belt tensions aren't supposed to be equal using the new method.
RE: VFA Artifacts on X+Y Straight Edges
Ah! I think I see my initial mistake. I kept strumming the belts on the sides. Eith the extruder in front it was much worse to access....
I have to strum the belts that are in front left of the extruder. I messed that up 😀
RE: VFA Artifacts on X+Y Straight Edges
patiently waiting for @malpan to start selling his compliant pulley's in his web shop 🤣 .
Sad to hear your idea didn't work but pressure is on for me now I guess 😅. I hadn't planned on selling things but I guess I could investigate something. I'm going to try just making some moulds with fdm in the meantime. Why don't you try making a housing for the captive nut in TPU? It'll creep over time unless you use some of that CF TPU that's around though.
RE: VFA Artifacts on X+Y Straight Edges
The belt tensions aren't supposed to be equal using the new method.
I believe the aim of the new method is to get equal belt tension (if measured in the old positions), but the new method measures the frequency on unequal geometry, so they have to be set to different values at the new position to achieve equal values at the old position.
RE: VFA Artifacts on X+Y Straight Edges
patiently waiting for @malpan to start selling his compliant pulley's in his web shop 🤣 .
Sad to hear your idea didn't work but pressure is on for me now I guess 😅. I hadn't planned on selling things but I guess I could investigate something. I'm going to try just making some moulds with fdm in the meantime. Why don't you try making a housing for the captive nut in TPU? It'll creep over time unless you use some of that CF TPU that's around though.
Yeah, that's an idea. What are your thoughts on the hardness of TPU versus the silicone insert you used, and their relative merits for damping resonance? Could the TPU be inferior in this respect?
RE: VFA Artifacts on X+Y Straight Edges
The belt tensions aren't supposed to be equal using the new method.
I believe the aim of the new method is to get equal belt tension (if measured in the old positions), but the new method measures the frequency on unequal geometry, so they have to be set to different values at the new position to achieve equal values at the old position.
I get that, but all this seems to be doing is increasing the overall tension by a few Hz... We've all tried various different frequencies over the last few months without any real improvement in VFAs.
Honestly I think there's more chance of my dog starting to speak English than there is of this method making any real difference to VFAs.
RE:
Made a draft for you @chris-hill:
https://www.printables.com/model/1358406-experimental-mod-for-vfa
Urethanes are generally really good at absorbing vibrations, that's why Sorbothane is made from it. My only issue with TPU is it's tendency to creep, particularly in warm environments of a printer. Since it's stiffer than silicone you'll just need more.
RE: VFA Artifacts on X+Y Straight Edges
The instructions are a bit unclear regarding which belt to pluck, especially when people still have the old method in their mind.
So, instead of pushing the linear rail beam with the print-head backwards and plucking the belts on the left and right - we need to pull the rail-beam forwards, and pluck the upper and the lower belts on that rail beam, right?
Anyone tried the updated belt tuning guide ? The web app now has the waterfall plot which will hopefully make tuning it easier, and the tuning instructions have now completely changed, target frequencies are higher, although that might be related to the new position of the extruder when tuning.
Any effect on VFAs?
RE: VFA Artifacts on X+Y Straight Edges
Did you have to change the voltage compared to the original version?
That's probably a translation error -- you mean "change the tension", right? Both terms translate into "Spannung" in German, but in English they are different for the mechanical vs. electrical domain.
The funny part is that while I prefer English, my first name is Gerhard. First generation American of German parents. 😉
RE: VFA Artifacts on X+Y Straight Edges
The instructions are a bit unclear regarding which belt to pluck, especially when people still have the old method in their mind.
So, instead of pushing the linear rail beam with the print-head backwards and plucking the belts on the left and right - we need to pull the rail-beam forwards, and pluck the upper and the lower belts on that rail beam, right?
Anyone tried the updated belt tuning guide ? The web app now has the waterfall plot which will hopefully make tuning it easier, and the tuning instructions have now completely changed, target frequencies are higher, although that might be related to the new position of the extruder when tuning.
Any effect on VFAs?
Yeah, I guess the plucking is now done on the X axis, where the linear bearing is.
Unless I've got that completely wrong.
Not directly related but I've now got the headache of dealing with a spinning square nut in the left pulley holder. 😂
RE: VFA Artifacts on X+Y Straight Edges
The instructions are a bit unclear regarding which belt to pluck, especially when people still have the old method in their mind.
So, instead of pushing the linear rail beam with the print-head backwards and plucking the belts on the left and right - we need to pull the rail-beam forwards, and pluck the upper and the lower belts on that rail beam, right?
Unclear indeed, so I tried both. Left to right, stock settings (old method - 85Hz), new setting by plucking on the side like before and new settings by plucking in front:
So I wanted to go back to the middle result, i.e. new values and plucking on the side, BUT now I joined the club of belt tensioning screw stripped... Assembled unit.
CORE One is currently down, go back to a real workhorse - the MK4S - to save the day jobs...
RE: VFA Artifacts on X+Y Straight Edges
I just tried the new web version. My belts were previously set by the old method, but I had slightly higher tension than the old 85Hz recommendation because it seemed to improve VFAs with my GT1.5 belts.
When I checked just now, using the old method, the left belt measured 94Hz and the right 93Hz. Without any adjustment, measuring at the new locations I got 90Hz for the upper and 84Hz for the lower.
So then I adjusted the upper to 98Hz and the lower to 92Hz, as per the new instructions. I then remeasured at the old positions and got 103Hz for both sides. Gantry still square.
This is on an iPhone 13 Pro, and the results were quick and easy - the waterfall plot is a nice extra, but I didn't need it for the measurements.
My take-away from this - Prusa seem to be aiming for a somewhat higher tension than before - 103Hz in my case, versus the old recommendation of 85Hz - and they've moved the measurement point probably just to make it easier to access and easier to guarantee a repeatable gantry position, but the result, when both belts have the same tension, is slightly different readings (upper versus lower) due to the asymmetric position of the print head.
My experience mimics yours.
The gcode based Robo Alpaca printed flawlessly using Overture Blue Silk PLA. In fact, the print quality is astoundingly good. Without supports it almost printed the belly perfectly as well. ...but VFA is what I was looking for, and it is not apparent on that print.
However, it's likely a tweeted gcode by Prusa, so I got the STL, sliced it, and I'm printing another one that will not be tweaked. I will get pictures of the two from various directions and post them later.
I will also run the VFA test from a gcode based model and post that information / picture here as well.
The 6.3.4-RC firmware did show minor improvements in VFA prior to tensioning the belts using the newer webapp and different belt locations.
To reiterate: I did not have any issues using the webapp or performing the updated belt procedure. Of course, if I had used German based instructions then the procedure may been more detailed / specific, and I wouldn't have suffered from a lack of self-confidence like I did with the English instructions! 😉 Bahaahhaahaha
RE: VFA Artifacts on X+Y Straight Edges
I just got back from the chat with the user support. They confirm that the method I described is the correct one, and they said they will make the instructions more concise.
The instructions are a bit unclear regarding which belt to pluck, especially when people still have the old method in their mind.
So, instead of pushing the linear rail beam with the print-head backwards and plucking the belts on the left and right - we need to pull the rail-beam forwards, and pluck the upper and the lower belts on that rail beam, right?
Unclear indeed, so I tried both. Left to right, stock settings (old method - 85Hz), new setting by plucking on the side like before and new settings by plucking in front:
So I wanted to go back to the middle result, i.e. new values and plucking on the side, BUT now I joined the club of belt tensioning screw stripped... Assembled unit.
CORE One is currently down, go back to a real workhorse - the MK4S - to save the day jobs...
RE: VFA Artifacts on X+Y Straight Edges
I just got back from the chat with the user support. They confirm that the method I described is the correct one, and they said they will make the instructions more concise.
CORE One is currently down, go back to a real workhorse - the MK4S - to save the day jobs...
Thank you for doing that! Very helpful!
RE: VFA Artifacts on X+Y Straight Edges
Made a draft for you @chris-hill:
https://www.printables.com/model/1358406-experimental-mod-for-vfaUrethanes are generally really good at absorbing vibrations, that's why Sorbothane is made from it. My only issue with TPU is it's tendency to creep, particularly in warm environments of a printer. Since it's stiffer than silicone you'll just need more.
Thank you. I dug out my silicone vacuum hose, and unfortunately it's 4mm ID, 8mm OD, so it's not going to work with the M3 spindle bolt. But it can be cut to make a piece to stuff into your modified tension idler holder. Or I may further modify the holder to use a ring slice of the hose between the square nut and the holder, taking care not to let the nut pull out of its square recess, naturally.
I've also ordered a few ID 8mm, OD 12mm x 3.5mm bearings. If I print a couple of flange washers, and adapt the idler mount to use an M4 spindle (or even print a tiny sleeve for an M3 spindle) then I should be able to use a length of the hose as a damper between the spindle and pulley bearings. The belt would then run on the bearings directly.
RE: VFA Artifacts on X+Y Straight Edges
It's nonsense really, I just got the belts all tuned up...and will have to do it again in a few days when my replacement PCCF belt tensioner pulley turns up 😂
I had to print a temporary tensioner pulley in PETG-CF on my Prusa mini that's been happily retired for about 6 months...(I had to print some parts that were being collected at 2PM)... The print quality of the temporary tensioner pulley is terrible but as long as it can last until the replacement arrives then I'll be happy.
Looks like my decision to keep the Mini on the subs bench paid off.
RE: VFA Artifacts on X+Y Straight Edges
Printing of Robo, alpaca to test VFA with new belt and firmware… VFA test next:
Gcode Robo Alpaca on right, sliced Robo Alpaca on left, testing of new firmware and belt procedure
RE: VFA Artifacts on X+Y Straight Edges
Just need the outer bearings now.
RE: VFA Artifacts on X+Y Straight Edges
The plan is for the belt to ride directly on the bearings? I'd add a small shoulder on your carriers so there's no risk of contact/friction on the bit of the bearing you want moving. Though ideally that would also be in a compliant material. Flanged bearings might work better so there's no chance of belt riding on surfaces you don't want moving. Will be curious to see how this works.
Just need the outer bearings now.
RE: VFA Artifacts on X+Y Straight Edges
VFA Test Tower for Core One out takes:
