Having owned a P1S since December '23, I recently measured V3D’s latest califlower and observed a skew angle of .23 degrees in the printed part (100% scale, standard BambuLab green basic PLA - the one shipped with the printer w. AMS, standard profile). Noticing other users reporting smaller skew angles (feel free to refer to CNC Kitchen’s latest YouTube video on the topic) and decided to re-adjust the belt tensioning per the official procedure, calibrate, and repeat the print.
Surprisingly, the resulting print showed a significantly smaller skew angle, now at 0.06 degrees. However, I have observed that the belts are no longer centered on the adjustable pulleys and both belts are touching the bottom sides of their designated guides. Is this outcome expected from the official procedure, and if not, how can I correct this?
Tried adjusting the angles of the pulleys by individually loosening one of the screws, but I can’t seem to find a position where both belts consistently stay perfectly centered on the guides (i.e., maintaining the same position after several print head x/y travels).
Additionally, I’m curious if there’s any official information on the torque required to tighten the screws holding these pulleys in place. Your insights and suggestions on these matters would be greatly appreciated.
Thank you in advance for sharing your experience and thoughts with the community!
Unless your printer is in a gravity-free environment, I don’t know how the belt could be expected to be anywhere except the bottom of the pulley. It’s not a problem.
It’s why it has a flange. To keep the belt from walking off the idler. But you do want to try and align the two screws to vertical. If the idler is tilted, the belt will run harder against the top or bottom (depending on tilt direction) flange and that’s going to cause faster wear, noise, and possibly visual artifacts in the print.
Part of my original attempt, I tried to adjust the angle of the pulleys but no setting would consistently keep either of the belts centred. I was hoping to find some sort of procedure that would lead to a better belt alignment, in addition to the re-tensioning.
As I searched the web for photos of other bambulab corexy printers, it looks like there is no default belt position after the completion of the official belt tensioning procedure. For example, directly from their wiki, the belt is seated on the opposite side of the pulley vs the seating shown on mine:
I had the same. After adjusting the tensioner, the belts are not good aligned. They made even a scratching sound. I saw some pctures from other printers where a horrible amount of belt-debris is shown. Bambu stated as ususal: all okay. Or … even better … use grease on the back side of the belt Nonsens in my poor eyes.
I did again the tensioning procedure and after that a few fast prints. Then, same as you did, only loosen one screw of the tensioner and very carefully, during print, put a little force to the plastc part of the tensioner. The belt moves in the oposite direction (as expected). It takes a while to find out the correct position/force and you need to wait a few minutes until the hole system is settled. Maybe need to do it several times. I found a good position after 2 or 3 trials. About 95% of printing time the belt is somewhere in the midle. 5% its slighty touching the flange. This is okay. Finally doing the vibration compensation. Finish.
No more strange sounds and prints are looking good. I am happy with it.
Looks like the tensioner is one more part which should be improved to avoid an angle on the tensioner pully. Belts, their tension and a perfect smooth running are the main important things for core xy machines.
hey there, i had problems with my p1s making scraping sounds and pinpointed the cause being the belts scraping on the bottom of the pulley. after readjusting and re-tensioning the belts multiple times the right belt stays on the upper middle part of the pulley, the left one moves quite a lot though. the sounds is gone, but i have never noticed movement (never really examined the belts while printing either to be fair). your comment makes it sound like belt movement up and down is expected behavior though, am i correct in that statement? thank you in advance!
If its expected from Bambu I don’t know. But if I look to the mechanics I found 9mm pulleys but a 7.7mm belt. So i guess it is expected. Prints are very exact (I tested with califlower), so its no problem.
Nonsens in my poor eyes.
