What is causing 'droplets' on first layer?

  • I recently changed filament and for starters it worked perfectly well, but quickly I got some problems with my first layer. It's like droplets are forming on the surface (finished item + 3 undersides):



    enter image description here



    The final part is (for me) okay but I'd like to get rid of those pesky 'drops'.



    As the defect is quite stable and quite recognizable and it happens all the time, I bet somebody more experienced than me knows what's going on!



    Info:



    I'm using a 1 week old eSun filament, a E3D V6 Hotend 1.75mm on my scratch CoreXY printer, short Bowden direct drive, Repetier, Marlin, Linear advance (M900 K60 so quite low).



    The print is done using a 0.4mm diameter nozzle at 0.2mm height at:



    50°C(122°F) heat-bed and 214°C(417°C) hot-end for first layer, then lower a bit to



    40°C(104°F) heat-bed and 211°C(412°F) hot-end.



    I use Blue-painter tape.



    Worked perfectly well with my black eSun and my white eSun.



    What's my problem?



    Thank you all!



    [Edit]



    Tried about everything (more temp, less temp, fan on item, more / less bed temp, underextrude, moving around z delta, removing linear advance, radically lowering speed) but the only thing that worked about okay (problem was quite reduced but didn't go away totally) was to bump up the layer thickness to 0.3mm



    [Edit 2] Finally it seems it was, as it usually is, a conjuncture of several problems that I will list here:




    • The bed was not perfectly flat

    • The heatbed moved/bended when going from a hot first layer to a colder second (and on) layer

    • Maybe the speed was a bit high for the first layer (25mm/s)



    I fixed this by installing a borosilicate glass bed on top of the heat bed which ensures a perfect flatness.



    I had to change my inductive sensor to an 8mm one (insteéad of the 4mm I had previously added) to make this function. I think it is not as good as it can be as it detects the heatbed under the glass (which is not perfectly flat), but it's enough for now. I'm thinking about how to make the glass conductive, like aluminium or something, but that's for another day/post.



    I also put blue tape on the glass because the first layer was tricky. This might be because the inductive sensor doesn't do its job that well (see above).



    Heatbed temperature for first layer: 70°C



    Extruder temperature anywhere from 190°C to 220°C works fine, that was not the problem, or it is no longer a problem.



    I also lowered the first layer speed to 20mm/s because the first layer didn't stick easily directly onto the glass, with blue painters tape it sticks even too much so I'll try higher speeds. It did mitigate problems though so it might be a path to try if you run into similar problems.



    And now it seems that it works even amazingly well, I just have to print something really big to see!



    ---------------Old:



    Moving z up made spaghetti :-) and different temperatures made quite extreme warping:



    enter image description here
    enter image description here


    What's the step size in the Z axis for your printer?

    I used 0.2mm getting these problems, 0.3mm works better but still not perfect. Or maybe you are wondering about the setup? It's a classic nema 17 with microstepping and a "lead screw" (http://cpc.cx/ld0) pushing a cantilever build plate running on two vertical 8mm (IIRC) rods with (2+2) linear bearings.

  • Valmond

    Valmond Correct answer

    4 years ago

    First of all, thanks for all the help, it really is a nice community!



    But none of them actually helped and I finally find out what to actually do to fix the problem so here it goes:




    • Extruder temperature didn't change anything (made it worse under 190°C/374°F)


    • Speed didn't change anything (tried as low as 10mm/s)


    • Z tuning didn't change anything


    • Using 0.3mm layers instead of 0.2mm made it slightly better but still completely unusable




    So, what did the trick?



    I figured that it was extreme warping, so heating up the heatbed to 80°C/176°F and the first layer comes down really good, for the rest of the print I use normal temperatures and it works okay. For overhangs I bump some degrees and point a small squirrel cage fan on the overhang.



    I think the filament is damaged or that this particular color might be a bit different than other colors, but well, now it works!



    [Edit] From a recent firmware upgrade the heatbed PID was disabled, re-enabling it really made it simpler too.


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Content dated before 7/24/2021 11:53 AM