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MK2 loosing z-position?  

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luc.o
(@luc-o)
New Member
MK2 loosing z-position?

I recently finished building and calibrating my MK2 and did two sucessful test prints (Prusa logo and tree frog). After that I tried to print this part

but near the end, the print became messed up

and the rest of the filament became stuck at the extruder

Unfortunately, I was not present to see it happen or to stop the printing. When I saw the mess, the part was lying behind the printer, probably pushed down by the nozzle.

Could it be that

  • the part did not stick well to the bed?

  • the nozzle somehow lost track of its z-position during the print?

  • I messed up the "Live Adjust Z" function during the first layer?
  • And what about the "bubbles" on the lower right?

    Any help will be welcome.

    Thanks,
    Luc

    Napsal : 19/04/2017 7:29 pm
    david.b14
    (@david-b14)
    Honorable Member
    Re: MK2 loosing z-position?

    If you did not slice with zhop enabled in Slic3r, give that a try.

    Napsal : 19/04/2017 9:56 pm
    luc.o
    (@luc-o)
    New Member
    Topic starter answered:
    Re: MK2 loosing z-position?

    I used the default settings in Slic3r (with zhop enabled). It was

    Print Settings: 0.15mm OPTIMAL
    Filament: Prusa PLA 1.75mm
    Printer: Original Prusa i3 MK2 with ZHop

    I just saw that there is a third button labeled "Slice Now". Should it press it before using "Export G-code" or is the latter one enough? I followed the manual at http://manual.prusa3d.com/Guide/Simple+Slic3r+tutorial/7 and there it did not mention "Slice Now".

    Napsal : 19/04/2017 10:19 pm
    Nigel
    (@nigel)
    Honorable Member
    Re: MK2 loosing z-position?

    I use Simplyfy 3D my slicer of choice. I do not have the issues many have here. It is worth paying for it, it owes me nothing, but great reliable prints. . I use it across my 4 different 3d Printers and get great results. I do not use Z hop. My printer of choice is my Prusa I3 MK1 built from a kit with later added upgrade from Prusa to a Mk2 ( a few days after I bought my MK1 kit) Prusa served me well, I have no complaints about my MK2 upgrade kit.

    My Prusa I3 Mk2 is working really well and gives me great prints. I have ordered the MK2S upgrade kit, but will wait a while to install it. If it aint broke, don't fix it 🙂

    Nigel
    Life is keeping interested and excited by knowledge and new things.

    Napsal : 20/04/2017 5:41 am
    tomasz.p
    (@tomasz-p)
    Active Member
    Re: MK2 loosing z-position?

    Did you use Bed level correct from Calibration menu in printer? For me it looks like your right side of bed is a bit higher so nozzle just rammed into print and tried to print further. Frog and Prusa logo are small prints located on center of bed so your live Z may be correct for center of bed, but may need some tuning for other sides of bed.

    Rmember that when nozzle is too close to bed layer becomes thicker because of fillament moving to sides from nozzle, this is visible on your print. Even if it's just a bit on first layer, after some more layers it cumulates this much and can cause serious problems.

    Napsal : 20/04/2017 6:50 am
    luc.o
    (@luc-o)
    New Member
    Topic starter answered:
    Re: MK2 loosing z-position?

    Thank you all for your suggestions. I made it work now.

    I first tried with "bed level correct" and the V2_calibration.gcode, but even after using the maximum values of +-50 um, I could see that the bed was not even. The solution finally came when I checked the screws fixing the heatbed to the Y-carriage. One of them, at the back right, was just a little bit loose. After tightening it and redoing the calibration, everything looked fine.

    I did a test with two small beams in the X and Y direction, respectively, as shows the picture below.

    Napsal : 22/04/2017 1:42 pm
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