Layer shift in certain hight
Hi there,
After a few headaches with MMU printing, I have to say that the MMU2S works perfectly on my MK3S+. That is, exemplary filament tips, no problems with filament changes, no grinding, sticking or stringing and no sensor issues, which I experienced before.
However, I have now experienced a layer shift seemingly at the quite same height three times. The first time without crash detection. The second time with crach detection, and finally without crash detection, with the model and tower shifting to different, more distant locations.
Strangely, the first two prints shift to the right, while the third is shifted to the back.
I once observed layer shifts that were due to excessive belt tension. After losing the belts to 258/257 these issues disappeard (this was before the MMU2S upgrade).
Do you have any idea what could be causing this problem or what I could change?
Thanks in advance!
Best Answer by sbZHDtH:
Thanks a lot for your feedback!
Before the MMU2S, I have already gone through the basic setting. All axes move smoothly and evenly. The resistance is constantly the same. All screws are tight (according to the manual). Well, except for the screws of the tensioning system, which are a little tighter.
I also have already printed out the Tension Meter and used it for calibration.
However, after posting this I thought about:
Strangely, the first two prints shift to the right, while the third is shifted to the back.
So I made another print where the distance between the model and the tower was even greater and the tower was behind the model. This time the print went through without any problems. Well, except for the loading problems caused by the Fillamentum Rapunzel Silver filament, which, by the way, I also had with the eSun Skin filament for another print.
I think the problem was ultimately that the purge tower was (still) too close to the model in the previous prints.
You're right to think this is not a MMU problem. It doesn't look like poor adhesion in this case so -
Try the usual round of checks with the base printer, for each axis:
First, with the power off, move the axis by hand; is is smooth? Does the resistance stay the same over the whole range?
Clean and lubricate the smooth rods, check they are not damaged/scratched. Check the idler pulley is not clogged, out of line, or damaged (loosen the belt and try turning it with your fingertip, is it smooth?)
With the belt loose try turning the stepper motor by hand; is is smooth?
Retighten the belt until it just begins to make a low musical note when plucked...
If the printer works, make your next print this:
https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus
It MUST be printed in Prusament PETG or the spring tension will be wrong.
Let us know how you get on.
Cheerio,
RE: Problem solved
Thanks a lot for your feedback!
Before the MMU2S, I have already gone through the basic setting. All axes move smoothly and evenly. The resistance is constantly the same. All screws are tight (according to the manual). Well, except for the screws of the tensioning system, which are a little tighter.
I also have already printed out the Tension Meter and used it for calibration.
However, after posting this I thought about:
Strangely, the first two prints shift to the right, while the third is shifted to the back.
So I made another print where the distance between the model and the tower was even greater and the tower was behind the model. This time the print went through without any problems. Well, except for the loading problems caused by the Fillamentum Rapunzel Silver filament, which, by the way, I also had with the eSun Skin filament for another print.
I think the problem was ultimately that the purge tower was (still) too close to the model in the previous prints.