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Are these vertical lines described as "banding"?

Would the most likely culprit be the extruder?

FWIW, this was printed in "vase mode".

Vase mode, PLA

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Banding usually refers to Z banding and manifests itself in a wavy/non-straight wall in Z direction:

Z-banding

This sort of banding is related to mechanical or design issues of the printer (lead screw (nuts), belts, play, etc.)

Your print, however, shows local thicker walls. It appears that these local thicker parts are related to the change in direction of the print head. A 3D printer does not print curved lines or arcs (although G-codes do exist for arc movement), all movements are straight lines. So the cylinder consists of straight lines. By rendering the cylinder with more triangels you could increase the amount of straight lines to form a better approximation of the cylinder circumference. You could also try to lower the printing speed, but since you did not post any printing parameters that will be a guess.

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  • $\begingroup$ interesting - I'll check the gcode when I get home to confirm it's not using actual arc movements $\endgroup$ – Roger Apr 17 '18 at 13:14
  • $\begingroup$ @Roger You don't have to check, it is using G0 and G1 codes. The STL file already converted your geometry into triangular pieces, so straight lines. Try if you can make the STL again, but now with a higher refinement of triangles. $\endgroup$ – 0scar Apr 17 '18 at 14:10
  • $\begingroup$ ok, I regenerated an stl using much higher detail, and printed it... which resulted in the same vertical lines at the same intervals! There are 30 vertical lines; the printed cylinder diameter is 50mm, and my extruder gear is a crappy 26T with 11mm outer diameter $\endgroup$ – Roger Apr 18 '18 at 2:35
  • $\begingroup$ I took apart the extruder assembly - everything seemed fine and clean. These lines only appear when I print in "vase mode", which leads me to believe it might have to do with my Z axis, e.g. maybe it "jerks"? $\endgroup$ – Roger Apr 18 '18 at 19:05
  • $\begingroup$ I don't think it has to do with Z because you see the same bugs at each layer. check your extruder teeth; you might be missing one, which would be much harder to detect outside of vase where re-work occours. $\endgroup$ – dandavis Apr 19 '18 at 3:29
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Ok, so it turns out that this was caused by a problem in my stepper motor drivers, which results in missed steps, as described on this guy's blog

The fix was to hook up these "TL Smoother" modules (I got these particular ones from amazon but there are a bazillion clones)

After hooking up TL Smoother, this is what the print looks like:

enter image description here

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  • $\begingroup$ Living up to the name! $\endgroup$ – th3morg Apr 29 at 18:53

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