Print issues when printing 20mm cube for extruder multiplier

So I have updated Marlin to version 1.1.9 and it seem to have an effect on my extruder.

I recalibrated the E-Steps and this now works great. So I then tried printing a 20mm cube with with 0% infill, no top or bottom and only 1 wall with a thickness of 0.4.

This is the result. First few layers look great, then it all went wrong. Any ideas?

The 20mm "calibration" cube strikes again! I don't know whose idea it was to "calibrate" a 3D printer with a 20 mm cube, but they were probably someone who never 3D printed anything.

20 mm is too damn small to calibrate anything. The nozzle comes back and lays fresh, hot plastic down on top of still hot plastic. The result is that after a few layers, the thing starts to sag and turns to crap.

If that's PLA, turn on the print cooling fan. Print it larger and slower so the plastic has time to cool and stiffen up before the nozzle comes around and dumps more plastic on it. Or print multiple copies in one go. The time it takes to travel between the different parts will allow the plastic to cool a little between layers.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]