Printer head hits end of belt and messes up print position during print
To start with, I am far from an experienced 3D printer, so go easy on me.
I am trying to do print a model that I have already successfully printed twice. I need it to print the same model two times more. But it failed to print the model for the two attempts I've done now. I've seen what happens what goes wrong during both attempts but I didn't manage to film it sadly. However, I can explain what it did. It does exactly during the print, what I do (manually) in the attached video. The printer head moves over to the far right to the end of the belt and then the the motors try to move the the printer head even further what causes the belt to slip. This messes up the position of the printer head and it continues (sometimes it displays 'crash detected') with printing the remaining layers in the air at which point I have to stop the print manually to prevent it wasting more filament. The first failed attempt it already had done 25 of the 26 hours of print time. The second attempt failed around after two hours (of 26) in. As you can see in the attached image, it also leaves some materials (of the belt?) below the right motor.
I have no clue on what I am doing wrong. The first layer is fine and the printed part of the model sits firmly on the print bed. So no issues there. I would appreciate any help.
RE: Printer head hits end of belt and messes up print position during print
Hmm video is not showing up. Here a direct link: https://forum.prusa3d.com/wp-content/uploads/2022/07/WhatsApp-Video-2022-07-26-at-1.21.55-PM.mp4
RE: Printer head hits end of belt and messes up print position during print
Sorry for the replies, but I can't edit the posts anymore. I've done the following:
- Ran a belt test, the result was OK.
- Ran a self test, the result was also OK.
- Ran a whole new XYZ calibration.
Please show us the back of the E axis where the cable bundle enters the extruder.
Cheerio,
RE: Printer head hits end of belt and messes up print position during print
Thanks for the reply @diem! Do the following images suffice?
Not as as as I expected but just far enough out of place to be suspect.
The box ends of the zip ties need to be positioned directly on top of the cable bundle or they can hinder the last few millimetres of travel.
Try watching them as your head cashes - are they pushed hard against the power supply?
See step 70 on: https://help.prusa3d.com/guide/5-e-axis-assembly_169235
Cheerio,
RE:
I've moved the printer head to the right as far as possible and I can see room between the box ends and the power supply. However, the zip tie closest to the printer head was slightly touching or very close anyway to the printer frame. So like you said, I've moved the box ends to the top of the cable bundle just to be sure.
The thing is, this problem happened twice randomly when I was in the room and it happened very fast. When it happened, I heard the sound (same as the video I've added in previous post) and before I could reach the printer the screen said 'crash detected', it 'recovered' itself and continued printing. Only after it 'recovered' itself, it continued printing the remaining layers in the air because it doesn't know the correct position of the partly printed part anymore. It follows the shape of the printed part but it does it like ~5cm to the right of the position of partly printed part.
Do you reckon I should try it again now that I moved the cable boxes of the zip ties?
Yes. Try again.
The belt skipping a cog suggests your belt tensions may need attention as well.
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.
Cheerio,
RE: Printer head hits end of belt and messes up print position during print
Thank you!
Hmm, I only have Prusament PLA at the moment. I will try to print it again and I'll let you know the results!
RE: Printer head hits end of belt and messes up print position during print
Ok. So I have tried to print again. Same problem again, twice! But now I managed to take a video of it.
This is the first error. This time it stopped printing and asked me the print should be continued. Which I did (left a line though).
https://forum.prusa3d.com/wp-content/uploads/2022/08/IMG_6249-1.mp4
This is the second time (after 22 hours of printing 🙁 ). The second time it kept on printing (not noticing any crash) but with a messed up position like explained in the OP (second video).
https://forum.prusa3d.com/wp-content/uploads/2022/08/IMG_6250.mp4
https://forum.prusa3d.com/wp-content/uploads/2022/08/IMG_6251.mp4
RE: Printer head hits end of belt and messes up print position during print
I used the printable gauge, but here is another method of adjusting belt tension:
https://guides.bear-lab.com/Guide/10.+Final+adjustments/51?lang=en#s668
That print is tall enough to stress the first layer - please show us the underside of a failed print. Your videos don't show the trigger event, we can assume a crash which might be caused by the part moving slightly.
What is that smeared on the build plate? If it is some sort of adhesion promotor you are using far too much...
Cheerio,
RE: Printer head hits end of belt and messes up print position during print
Here are the undersides of the failed prints (some supports in the bottom groove of the middle print broke off when taking it off the build plate). I am using some sort of a glue (see images) that came with the printer as I recall, not sure anymore though since it was a while ago that I got the printer. Someone, somewhere on a forum suggested when having first layer adhesion problems. Since then I use this, never had the first layer coming off again.
So I spoke with Prusa support and they said my belt tightness values are way off (too tight). Didn't know the correct values before, just looked at the OK result of the belt test. So I am gonna look into that in the meanwhile.
Bad belt tension does cause a lot of grief. The built in test measures the resistance to motion and in a well set up machine this does equate, roughly, to belt tension but it can easily be fooled by other issues.
There is a little discolouration in parts of your first layer, sometimes a sign of poor adhesion, but not too bad.
The PVA glue is to be used sparingly. One good wipe spread around with a wet tissue is enough.
Cheerio,
RE:
Thanks. I will minimise the use of the glue! The values below (see image) are current for my belt tensions. I was told this need to be between 260 and 290 (the lower the tighter and preferable around 275), so I have some tweaking to do. It seems to be most obvious issue so I will go and fix that and test a print again. I will report back with whether or not the print succeeded. I do think the height also plays a roll because this is the first print I am printing that goes this high. Not sure which role though.
Either way thanks for the replies and help!
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.
Cheerio,
RE: Printer head hits end of belt and messes up print position during print
This is a clever way to properly tension the belts if you don’t have the gauge or the right filament to print one on hand. I think I’ll give this a try on my next maintenance service. Thanks for the tip @netpackrat !
I used the printable gauge, but here is another method of adjusting belt tension:
https://guides.bear-lab.com/Guide/10.+Final+adjustments/51?lang=en#s668