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Filament bends around the nozzle  

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Desti
(@desti)
Eminent Member
Filament bends around the nozzle

Hello! I have my Prusa I3 MK3 for 7 months already and it recently started to fail for no reason I can see.
To summarize, the filament doesn't want to go well on the bed and instead bends itself and goes directly around the nozzle.

I checked online and saw that it's often because it's clogged but I make a couple of cold pulls, and if I make a Load filament with the Z axis a bit higher it comes out with no issue: https://drive.google.com/open?id=1JE0U9AXC7lHOfCmbGqv8IhZOmCkekN8c

But then if I just want to make a First layer calibration it quickly gets messy. The first corner line comes out well, but when it tries to make the lines sometimes it goes well on the bed and at some moments it stops and goes around the nozzle:
https://drive.google.com/open?id=1aKP1w1GTy9eWXoWKX3Zq70Ss3cDAeKGA
https://drive.google.com/open?id=1x2qFE3qEZm6on-Rx2iDWeSey985_89Aq

I've obviously tried many times to adjust the live Z axis and it's either too close and nothing comes out (and I risk to damage my bed), or as soon as it's high enough to have filament to come out it bends around the nozzle.
I've tried with many PLA filaments and it always does the same.

I've also tried to redo the XYZ calibration but still nothing.

I'm a little lost. If anyone has suggestions I'm open to anything at this point ^^'

Napsal : 02/04/2019 1:28 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member
Re: Filament bends around the nozzle

The Z level seems to be quite good on the left side but slightly too high on the right side.

But I think the biggest problem is a dirty bed.
Wash with detergent and warm water and then wipe with paper.

Forget acetone and isopropanol, detergent and hot water are by far better.

Bear MK3 with Bondtech extruder

Napsal : 02/04/2019 3:14 pm
bobstro
(@bobstro)
Illustrious Member
Re: Filament bends around the nozzle

You are having bed adhesion issues. Here's some copypasta...

Adhesion problems are usually caused by 2 main problems:

  • A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. Take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails, and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent to give it a very light buff, but only infrequently.

  • . If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine.
  • And above all else, avoid touching the PEI print surface.

    Try those 2 steps. If you're uncertain of the Live-Z results, post pics here of the 75x75 print bottom and you'll get quick help. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When it's right, you should be able to gently rub it without it coming loose.

    And above all else, avoid touching the PEI print surface.

    Once you get that fixed, clean your nozzle and hotend. That filament buildup is going to cause any stray filament to stick to the wrong thing and will eventually fall into your prints. Once clean, consider a silicone sock.

    My notes and disclaimers on 3D printing

    and miscellaneous other tech projects
    He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

    Napsal : 02/04/2019 3:15 pm
    Desti
    (@desti)
    Eminent Member
    Topic starter answered:
    Re: Filament bends around the nozzle

    I forgot to mention I clean the bed between every print with 99% isopropyl alcool.
    I'll try to clean using detergent and hot water then, thank you, I'll keep you updated!

    Napsal : 02/04/2019 4:39 pm
    bobstro
    (@bobstro)
    Illustrious Member
    Re: Filament bends around the nozzle


    I forgot to mention I clean the bed between every print with 99% isopropyl alcool.
    I'll try to clean using detergent and hot water then, thank you, I'll keep you updated!

    Specifically dish soap! Use Dawn or whatever the equivalent is locally. Other soaps can leave films or additives that will reduce PEI adhesion.

    My notes and disclaimers on 3D printing

    and miscellaneous other tech projects
    He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

    Napsal : 02/04/2019 4:42 pm
    Desti
    (@desti)
    Eminent Member
    Topic starter answered:
    Re: Filament bends around the nozzle

    That seems to have done the job indeed! 😀
    I cleaned with dish soap and hot water, then set the right side of the bed at -25µm and it seems to work quite well! The bed might be a little damaged though (on both side), not everything vanished but I think I can't avoid that.
    I still might consider changing the bed soon.

    Anyway, thanks a lot guys 🙂

    Napsal : 02/04/2019 8:30 pm
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