I just got an Ender 3 Pro for Christmas and, aside from firmware, I have made no changes to it whatsoever. Until yesterday, my printer was running all prints flawlessly. The only thing that changed was the filament, but I don't think that's the issue because the problem only starts to occur at a certain Z height.

What I've ensured:

  • The firmware is up to date
  • The filament is dry the X, Y, and Z axis all have no bumps or obstructions (lead screws and belts are fine; wheels and bolts all good, etc.)
  • I have the right temperature (200 °C as printed on my PLA filament's label)
  • The filament is not tangled
  • There is no nozzle jam
  • I have retraction enabled properly in my Ultimaker Cura settings
  • The file is not corrupt (I've remade it, re-installed Ultimaker Cura, reformatted my SD card, etc.)
  • The extruder is not slipping or chewing into the filament
  • My bed is leveled

What I've noticed aside from the crappy prints:

  • There's an intermittent "thump" sound coming from the extruder, that as far as I can tell, is caused by the wheels "snapping back" suddenly sometimes.
  • The filament seems to be from a cheap Chinese brand: Sunlu.

Images of a good print and a bad print. These are the same version of the same G-code file printed at the same settings on the same printer in the same conditions. (EDIT: I removed the good print images because of a logo they contained that I am trying to limit public exposure to.)

Side view of the badly printed model

  • $\begingroup$ Does it always happen on this same height? Does it also occur on other models? $\endgroup$
    – kosteklvp
    Jan 8 at 0:28
  • $\begingroup$ @kosteklvp, yes to both questions. $\endgroup$
    – FenFox
    Jan 8 at 1:01
  • $\begingroup$ This is most likely heat creep, lower the temperature with at least 10 degrees. Could be that your retraction is not optimal, if the Cura default, it is too large. What values do you use? $\endgroup$
    – 0scar
    Jan 8 at 9:01

1 Answer 1


The thump and the appearance of the print are indications of underextrusion. Tracking the source of this failure can be challenging, especially considering how many factors you've included in your question.

Consider to create a model of smaller or larger diameter than the existing troublesome object. Adjust the height of the model in inverse proportion to the diameter change, that is, if the diameter is smaller, increase the height.

For example, if the problem is heat creep in the nozzle, it can appear at a specific duration of the print. By decreasing the diameter of the object, the failure point should appear at a higher level, more or less confirming that time is a factor, pointing to heat creep.

Consider also to download and print a suitably configured temperature tower. This will allow you to reference the time factor again, but also allow you to expand the range of printing temperatures you can use for that specific color and manufacturer of filament.


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