Filament gets stuck on nozzle. Not clogged.  

Re: Filament gets stuck on nozzle. Not clogged.

Hi, I just made my Prusa i3 MK2S kit. I don't know what happened but now all the filament gets stuck on the nozzle or not sticking while using Live Adjust Z or just a print. I need to get my layer height set so I can use the printer. I don't know if I am impatient or it just does not work out for me. So far I used a lot of filament trying to get this right. I've tried redoing the PINDA and recalibrating. Still same outcome. Calibration works perfect, I get the message saying it is perpendicular congratulations, until first layer setup, where it all gets messed up. The temperatures are set default and the speed. I hope I make sense to you. Thanks! 😀

I made a video so you understand a little bit better:

Spankyty;

You need to calibrate your Z offset. Basically, the printer knows where the PINDA sensor is in Z, but it does not know where you nozzle is relative to the PINDA sensor. You do this by adjusting the "Live adjust Z" setting.

Your is way too high - the filament does not stick to the print surface. So you need more negative number on Live Adjust Z. The Prusa instructions say to do this live while the V2 Calibrate.gcode is running. That is trial and error, and I have found to be frustrating.

Instead Peter provide a method that gets me much closer, and they I just fine tune with the live printing.

Here is Peter's method: http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/print-not-sticking-to-print-bed-side-to-side-t1298.html#p13325

Start off with a cold printer.

1. Align the Z axis by moving up to the top
2. Ensure there is no plastic blob on the end of the nozzle
3. Settings/Auto Home
4. With 2 sheets of copy paper, use Z Live Adjust so that the paper just starts to drag between nozzle and bed
5. Remove paper and preheat to your filament type. allow temps to settle for a couple of minutes.
6. Run Auto Home again
7. This time, with a single sheet of copy paper use Z Live Adjust so that there is a light drag on the paper between nozzle and bed
8. Back off the Z Live Adjust by about 0.025mm
9. Run the V2 Calibration GCode and make final Z live adjust if necessary

This is based on paper stock being 0.1mm thick (approx).

Re: Filament gets stuck on nozzle. Not clogged.

Here is Peter's method: http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/print-not-sticking-to-print-bed-side-to-side-t1298.html#p13325

Hi Aaron.

Thanks for the reminder; I had forgotten about that. Good to see something I wrote so long ago is still of use!

There is an addition to that:

Print 5 calibration squares - 20 x 20 x 0.2mm with one in the centre and one each in the centre of each side.
Set the live Z adjust so that the centre square is printed correctly
Adjust the 4 sides using bed level adjust.

Peter

Re: Filament gets stuck on nozzle. Not clogged.

I got the very same problem just suddenly. I have printed with the same spool PLA for about 70-80% of the spool already, then I have printed with some PETG and a small print with ABS, then I changed back to that same PLA spool and it acts just like yours. Those weird blobs comes and the filament between the blobs is very thin and doesn't stick to the bed. I have cold pulled so many times that the filament is clear (with nylon).

I tried to print the new rambo case for the MK2S upgrade, but I think I'll upgrade all else since I can't get the filament / printer to work at all now. If the problem would go away by itself when the printer is actually MK2S instead of the MK2...

So weird, the printer have been working like a charm until now.

Re: Filament gets stuck on nozzle. Not clogged.

You need to calibrate your Z offset. Basically, the printer knows where the PINDA sensor is in Z, but it does not know where you nozzle is relative to the PINDA sensor. You do this by adjusting the "Live adjust Z" setting.

Your is way too high - the filament does not stick to the print surface. So you need more negative number on Live Adjust Z. The Prusa instructions say to do this live while the V2 Calibrate.gcode is running. That is trial and error, and I have found to be frustrating.

Instead Peter provide a method that gets me much closer, and they I just fine tune with the live printing.

Here is Peter's method: http://shop.prusa3d.com/forum/original-prusa-i3-mk2-f23/print-not-sticking-to-print-bed-side-to-side-t1298.html#p13325

Start off with a cold printer.

1. Align the Z axis by moving up to the top
2. Ensure there is no plastic blob on the end of the nozzle
3. Settings/Auto Home
4. With 2 sheets of copy paper, use Z Live Adjust so that the paper just starts to drag between nozzle and bed
5. Remove paper and preheat to your filament type. allow temps to settle for a couple of minutes.
6. Run Auto Home again
7. This time, with a single sheet of copy paper use Z Live Adjust so that there is a light drag on the paper between nozzle and bed
8. Back off the Z Live Adjust by about 0.025mm
9. Run the V2 Calibration GCode and make final Z live adjust if necessary

This is based on paper stock being 0.1mm thick (approx).

I did everything you said. I felt confident up until doing the live adjust Z, where of course it went wrong again. It just will not stick, it just gets stuck on the nozzle... Also just like Mervious' reply my printer did print up until now. I don't know how to fix this at all, I am using the firmware 3.0.10 which I'm pretty sure is the latest.

Update: The filament stuck perfect in the V2 calibration and I measures it with calipers. The thickness was 0.04 to 0.08mm. I kept doing that print until I got it to 0.1mm so now it's ranging from 0.10-0.12mm thickness. I hope that's fine. But of course it does not work when I do a test print... It all does not stick to the bed but it does on the nozzle... I'm highly confused. 🙁

Update 2: I tried V2 calibration again, now it doesn't stick to the left side. I changed the bed level in the settings and raised the numbers but now all of it is messed up. I reset the bed level settings, it's allll back where it started.. Nothing sticking. I'm giving up for the day, it's been over 4 hours of fixing.

Re: Filament gets stuck on nozzle. Not clogged.

So it is hard to diagnose without seeing it. I will just blast a bunch of ideas that come to my head and you can step trough them.

Question: Is the PINDA sensor loose? If it is able to move or jiggle, then your settings will be changing all over the place. The new mount on the MK2S is a huge improvement over the MK2 PINDA mount. When you get things working again, it is worth printing one of those. The MK2 mount can vibrate loose. If that has happened, tighten it back up.

The other one that gets people is keeping the bed perfectly clean. I mean perfectly. I have found a ritual that works for me - not saying it is right - but with a clean bed, the PLA will stick much better. My ritual is: (if bed has glue on it (from a PETG print, or if I put some on just to be extra sure for a PLA print (small surface area)) start with Windex. Clean rigorously. Then acetone. Clean rigorously. Then IPA (90%+). Clean rigorously. This really brings my surface back to the sticky PEI that I love. Between prints just IPA.

Have you tried using glue stick to increase the stickiness of the bed? Glue stick is strange stuff. It increases stickiness for PLA (on a colder bed), but decreases stickiness for PETG (which will weld itself to a PEI sheet). People recommend the Elmers "purple" School glue - available all over. It works well for me, and the purple helps me know when I have cleaned it all off the bed when I want to go back to PEI.

Have you cleaned and inspected the nozzle tip? If ti is bent or has a burr it might catch the filament, and keep it from hitting the bed hard. Maybe it crashed into the bed and bent? I have not seen this happen, but it could be something that changed that you should look at. I run cleaning filament through mine occasionally, but I am not sure it is needed. The question is this. If the head is up from the bed (say 100mm), and you have it extrude some filament (using Setting -> Move Axis -> Extruder) does it come out as a nice clean thread? OR does it curl back on the nozzle. That is a sign of a clog or bad orifice or some such thing with the extruder itself.

Hopefully this gave you some things to try to check out. Let us know your observations and maybe other things will come to mind.

Re: Filament gets stuck on nozzle. Not clogged.

So it is hard to diagnose without seeing it. I will just blast a bunch of ideas that come to my head and you can step trough them.

Question: Is the PINDA sensor loose? If it is able to move or jiggle, then your settings will be changing all over the place. The new mount on the MK2S is a huge improvement over the MK2 PINDA mount. When you get things working again, it is worth printing one of those. The MK2 mount can vibrate loose. If that has happened, tighten it back up.

The other one that gets people is keeping the bed perfectly clean. I mean perfectly. I have found a ritual that works for me - not saying it is right - but with a clean bed, the PLA will stick much better. My ritual is: (if bed has glue on it (from a PETG print, or if I put some on just to be extra sure for a PLA print (small surface area)) start with Windex. Clean rigorously. Then acetone. Clean rigorously. Then IPA (90%+). Clean rigorously. This really brings my surface back to the sticky PEI that I love. Between prints just IPA.

Have you tried using glue stick to increase the stickiness of the bed? Glue stick is strange stuff. It increases stickiness for PLA (on a colder bed), but decreases stickiness for PETG (which will weld itself to a PEI sheet). People recommend the Elmers "purple" School glue - available all over. It works well for me, and the purple helps me know when I have cleaned it all off the bed when I want to go back to PEI.

Have you cleaned and inspected the nozzle tip? If ti is bent or has a burr it might catch the filament, and keep it from hitting the bed hard. Maybe it crashed into the bed and bent? I have not seen this happen, but it could be something that changed that you should look at. I run cleaning filament through mine occasionally, but I am not sure it is needed. The question is this. If the head is up from the bed (say 100mm), and you have it extrude some filament (using Setting -> Move Axis -> Extruder) does it come out as a nice clean thread? OR does it curl back on the nozzle. That is a sign of a clog or bad orifice or some such thing with the extruder itself.

Hopefully this gave you some things to try to check out. Let us know your observations and maybe other things will come to mind.

I got it to print perfect with V2 Calibration. But the thickness of the filament is 0.06-0.08mm not 0.1mm, is that fine? Also with the test print I have some ripples which I think is easy to fix but there is a little area that it does not want to stick... 🙄 Is that where I use the glue stick?

[Update] I used the glue stick, it stuck perfectly but there are some ripples still. I tried to fix them but no success. How would I fix that?

http://imgur.com/ROCZUIE
http://imgur.com/T4MaAAJ

Re: Filament gets stuck on nozzle. Not clogged.

There are more experienced people here than me, but I think that wrinkling is that your nozzle is TOO LOW, and plowing through the first layer.

I would bring it up some with Live Z adjust, while it is printing the PRUSA logo (gives you time to see it) until it is smooth.

This thread may help:

http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/life-adjust-z-my-way-t2981.html

There are a few calibration methods in this thread that are useful.

Re: Filament gets stuck on nozzle. Not clogged.

There are more experienced people here than me, but I think that wrinkling is that your nozzle is TOO LOW, and plowing through the first layer.

I would bring it up some with Live Z adjust, while it is printing the PRUSA logo (gives you time to see it) until it is smooth.

This thread may help:

http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/life-adjust-z-my-way-t2981.html

There are a few calibration methods in this thread that are useful.

Thank you so much! Everything works okay now! 😀

Re: Filament gets stuck on nozzle. Not clogged.

But how did you fix it?

Re: Filament gets stuck on nozzle. Not clogged.

Hi,

I appear to have the same problem (after switching to PLA from PETG). Did multiple cold pulls, even changed the nozzle for a brand new one, cleaned the bed with Acetone and IPA, yet the filament (Plasty Mladec PLA - tried multiple spools, including brand new one to make sure I haven`t been using some old that might have been humid) curles and stick to the nozzle rather than print bed. If I adjust the Z live, I get it to stick a bit but then the nozzle just pulls it off. It has been very frustrating and not sure what else I should be looking at.