I have bought an Ender 3 Pro in November. I loved 3D printing and even upgraded my machine to improve my experience. However, lately, I can't print anything due to an issue I can't seem to resolve.

I will provide as many details as I can in an orderly fashion.

  1. My machine: Ender 3 Pro w/ BLTouch clone installed. Running Marlin's latest bugfix branch. Also has a Raspberry Pi with Octoprint built into the PSU so I can control both the Power and functionalities of the printer. I have a glass bed, red aluminum extruder.

  2. My settings:

    • Printing with PLA;
    • Hot end at 200 °C;
    • Bed is at 70 °C;
    • ABL is on;
    • Nozzle: 0.4 mm;
    • Layer height: 0.2 mm;
    • Slicer: CURA
  3. The issue: While the first layer is printing, the filament bunches up around the nozzle and if it somehow touches the bed (like I reduce the Probe-Z offset) it doesn't stick and drags on a few mm. It eventually sticks and keeps printing fine for long straight lines but it's impossible to print a little circle inside, for example. The small details aren't printed on the bed, the filament just bunches up around the nozzle.

    Also when I do a cold pull(heat up to 200 °C then pull at 90 °C, the tip of the filament looks like this:

    Image of the tip of the filament

  4. I have tried the following:

    • e-step calibration
    • PID Autotune
    • Lowering/increasing temp (210-190 °C)
    • Lowering/increasing first layer speed (+/- 10-25 %)
    • Changing the heat block and the throat tube (twice)
    • Taking the entire hot end apart and cleaning it and changing the nozzle (even re-cutting the PTFE tube) multiple times

My theory is that the heat traveling up the cold block thins out the filament, causing under extrusion. The filament can't properly stick to the bed because it's too thin. But the hot end fan works. Should I still replace it?

Or is my problem something completely different?


1 Answer 1


This sounds like nothing but a bed leveling (distance from nozzle to bed) problem, though you may have introduced other problems disassembling the hotend. It's normal to have material oozing and bunching up before the print starts; this is why you start printing with a priming line or skirt.

Clean the bed well with isopropyl alcohol, level it (paper method at Z=0 or feeler gauges at Z=0.1, I prefer the latter), then fine tune with a leveling test print. If you're still having problems make sure the PTFE tube is tensioned against the nozzle right inside the hotend. Having any gap will make for all sorts of problems.

  • 2
    $\begingroup$ It really was about the bed. Reinstalled my old magnetic bed and everything is working fine now. Thanks so much. $\endgroup$ Commented Apr 10, 2021 at 18:36

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