Y-axis belt touching belt holder — is this normal?
Hi all,
I'm doing some maintenance on my mk3s+ after a long pause. I noticed that the Y-axis belt seems to touch the plastic belt holder under the bed. I’ve attached a photo for reference:
The belt isn't fraying, it moves smoothly,tension values seems fine,
Is this expected, or should I make adjustments to avoid long-term wear?
Thanks in advance for your help!
Best Answer by blauzahn:
The legs of the belt are not parallel. On the right side it is wound around the screw in the wrong direction. That it should be corrected even if it does not solve your current issue directly. The non parallel belts introduce a little bit of non linearity in the y-positioning -- especially close to the front of the printer.
To reestablish the gap between lower leg and bracket it may suffice to move the idler bracket and/or steppper bracket down within the existing screw holes. The belt legs are supposed to be parallel to each other as well as to the y-axis rods. Please check that the the belt does not rub at the printer's frame either. Please also try to avoid rubbing the belt at the sides of pulley and idler.
The original tensioner is a mediocre design. Before correcting the belt I recommend to print a better one (e.g. adjustable-belt-tensioner). That is way more convenient. You can keep the old one installed. If you have PETG you can also print Prusa's tension-meter. Reprinting the original tensioner as is may be a good idea as well. Just in case.
RE: Y-axis belt touching belt holder — is this normal?
Doesn't rub on mine. It is close to the bracket. Cannot measure gap at this time.
RE: Y-axis belt touching belt holder — is this normal?
The legs of the belt are not parallel. On the right side it is wound around the screw in the wrong direction. That it should be corrected even if it does not solve your current issue directly. The non parallel belts introduce a little bit of non linearity in the y-positioning -- especially close to the front of the printer.
To reestablish the gap between lower leg and bracket it may suffice to move the idler bracket and/or steppper bracket down within the existing screw holes. The belt legs are supposed to be parallel to each other as well as to the y-axis rods. Please check that the the belt does not rub at the printer's frame either. Please also try to avoid rubbing the belt at the sides of pulley and idler.
The original tensioner is a mediocre design. Before correcting the belt I recommend to print a better one (e.g. adjustable-belt-tensioner). That is way more convenient. You can keep the old one installed. If you have PETG you can also print Prusa's tension-meter. Reprinting the original tensioner as is may be a good idea as well. Just in case.
RE: Y-axis belt touching belt holder — is this normal?
Yes, you're absolutely right — thank you! Here's a better view of the issue:
I’ll definitely rework the entire Y-belt setup and install the adjustable belt tensioner as suggested. It seems like a much more reliable solution.
Thanks again for your help and the detailed explanation, really appreciated!
RE: Y-axis belt touching belt holder — is this normal?
Yup, clearly visible.
Seeing the standard rubber feet: Consider replacing them by squash balls. The ones for pros with two yellow dots as they have the highest dampening. Gives a nice reduction of noise. You can find some holders for them on printables. Prefer those than reach a little outwards for improved stability. Piece of cake.
RE: Y-axis belt touching belt holder — is this normal?
Thanks you so much.
Have a nice day.
RE: Y-axis belt touching belt holder — is this normal?
Quick update: I’ve replaced the original tensioner with the adjustable one as suggested — thanks again for the tip! However, I’m a bit stuck now. The new tensioner seems to just slide freely and doesn’t actually tension the belt. I’m not sure if I assembled it wrong or if I’m missing something about how it's supposed to work.Here’s a photo of the current setup:
If anyone could explain how the adjustable tensioner is supposed to actually create tension (or what I might need to tweak), I’d really appreciate it!
RE: Y-axis belt touching belt holder — is this normal?
The axis of the idler is positioned more inwards. As a consequence you have to shorten the belt. Right? 🙂 You can do it by pulling it further into the old tensioner. I' recommend to cut it conservatively. Put the old one in a middle position, the new one into fairly loose position. Then you can figure out how much you need to cut.
The screws are of course way too long. You will find a way to make it work.
RE: Y-axis belt touching belt holder — is this normal?
Yes sorry you are totally right, the screw was the problem i just changed it with shorter one and it works flawlessly. Tanks you so much, have a nice day.