Belt tuning puzzle
I have not seen this discussed elsewhere -- hence am wondering whether it's some peculiarity of my Core One build of if others observe the same:
On either side of the printer, the belt is running along the depth of the CoreXY assembly twice: On its way to the belt tensioner and back. If we assume that the belt tensioner idler has negligible friction, the tension should be the same on both runs of the belt. Since the inner run is a bit shorter (free length between idlers), I would expect it to give a higher-pitched ton than the outer one.
But that's not what I find. Consistently, the outer belt gives me a higher-pitch tone when plucked. I initially thought that it might depend on the most recent direction of head movement, because contrary to the above assumption idler friction cannot be neglected -- but that does not seem to be the case. No matter from which direction I push the print head towards its "Y all the way back, X centered" position, the outer belt run gives me a higher tone.
Is your printer behaving the same? Do you have an explanation for this observation?
RE: Belt tuning puzzle
Is your printer behaving the same?
Hi Jürgen,I can't confirm that.
To me, the inner, shorter belt sounds higher.The outer, longer belt has a lower tone. When I measure them, they all have the same tension.
As far as can be verified with the mechanical measuring device, at least.
RE: Belt tuning puzzle
Thank you for checking, Rainer! The behavior you describe is exactly what I would have expected.
What could possibly be different in my printer? I should probably print one of the "better" tension meters and check the tension on the inner and outer belt segments. But why would the tension on the outer run always be higher, no matter which direction the most recent movement came from? Mysterious...
RE: Belt tuning puzzle
There's no logical explanation for this. The only thing I would check is whether all pulleys are rotating freely.
Loosen the belt tensioner completely and check all pulleys.
RE: Belt tuning puzzle
I believe I saw this when I was initially tuning my belts after assembling my printer, I can check again later today. Not exactly sure why they would be different though.
FYI: When properly tuning your belt tension, the print head is supposed to be in the back middle of the printer. There should only be one belt on each side to pluck for tuning. The print head is pushed to the front to check that the belts are not pulling the print head out of square.
I would re-check your belt tension with the print head pushed all the way to the back. The Prusa app is a bit finicky at times, but I did get both belts to get within 2 hz of each other. You can "sing" a note into the app and see if its working and see how sensitive it is.
RE: Belt tuning puzzle
FYI: When properly tuning your belt tension, the print head is supposed to be in the back middle of the printer. There should only be one belt on each side to pluck for tuning. The print head is pushed to the front to check that the belts are not pulling the print head out of square.
I would re-check your belt tension with the print head pushed all the way to the back. The Prusa app is a bit finicky at times, but I did get both belts to get within 2 hz of each other. You can "sing" a note into the app and see if its working and see how sensitive it is.
Yes, I was referring to the standard "tuning position", where the Nextruder is pushed all the way back and centered on the X gantry. You will still see two lengths of belt on either side: The same belt running to and from the belt tensioner. Those are the pairs with the puzzling difference in pitch between the inner and outer belt run.
The surprising pitch differences are not related to uncertainties caused by the tuning app. I can clearly hear by ear which tone is higher or lower, and it's "the wrong way round" outer, longer belt run has the higher pitch.
RE: Belt tuning puzzle
Hallo Jürgen,
wie ist deine Erwartung mit dem Core One? Du scheinst ihn ja noch zu haben. Halten oder ... Heute ist ein Tag, wo ich das Teil in die Tonne drücken will.
Irgendwas ist bei dem Teil buggy, HW, SW, oder was auch immer.
Für Reverse-Engineering werde ich nicht bezahlt, daher die Frage.
Gruß
Markus
RE: Belt tuning puzzle
Hi Markus,
I am still torn, but will probably keep the Core One.
I had certainly expected a product where at least the fundamentals (XYZ positioning and Nextruder) are more robust and polished. I was aware that Prusa had launched some printers prematurely in the past, but given the Core One's close relation with the Mk4s and the XL, I thought they would get this one right.
Not happy with the whole experience of waiting, ordering, pre-paying, waiting, and eventually receiving a product which even now is not ready yet -- six months after its launch, and four months after first shipments. But what other options do we have in this price range? Personally, I don't want to buy into Bambu Lab's increasingly closed ecosystem, and I don't want a "bare bones" printer like a Voron or Ratrig where I would expect to spend even more time tweaking it.
So I guess my Core One will stay. I hope either Prusa or the community will iron out the remaining issues over the next months. Some nice progress in the VFA thread just now, where belt routing seems to critically impact the belt ripple/VFAs. (Although I am not convinced that tweaking the pulley height is the final answer.) And phase stepping calibration, although not officially released, seems to have worked for multiple users who have tried it in firmware 6.3.3, and has helped to make the printer quieter.