new artifacts after flying extruder

Hi guys,

I have another one. I recently got the bondtec extruder and had to install it with a 90cm bowden tube, which worked but wasnt good for retraction.
So I went back to my flying extruder build I had used before.

The new extruder works great and the flying setup Ive been using a year, so nothing out of the ordinary.

Now im getting this really interesting artifact. Its a diagonal line that goes ca 30deg up the wall. Sometimes its just a little buldge, sometimes there is also 0,5mm missing extrusion.
Some examples:


(All fotos can be seen here)

Some further observations.
+most walls looke fine, no extra jitter or irregularites, extrusion is also consistent and retraction is spot on
+i tested different materials, so a material fault can be excluded
+on the cubes it only happens on one side, on the other piece its on both sides.

Lastly I tested a different slicer. I usually use the newest cura which works fine in the past and now I also tested craftware and surprisingly this cube came out without the diagonal line:

BUT when I printed the other shape I saw that on the last topmost layer a diagonal line was creeping in.

You can see on the top edge slighty to the left of the center.

Its very weird since the walls below are fine. I thought about other causes like direction or layer change but that all doesnt make sense.

Any ideas?

I'm thinking it might be oozing from when the z layer changes.

The layer change is randomized, those are the little zits everywhere.

Hi, did you solved this diagonal banding issue?

It went away, but I dont know why. Most likely something mechanical.

Generally its some type of issue like a wheel with a flat spot, or something snagging at a certain spot (filament, wires etc...)

Quote
TheHebs
Generally its some type of issue like a wheel with a flat spot, or something snagging at a certain spot (filament, wires etc...)

reading on the web it seems to be a missing step that cause zebra stripes, i'm still unable to solve this

missing steps maybe, wouldnt the pattern be more random?

Acceleration values? Perhaps you need less acceleration with the heavier carriage.

My first thought was that there would be a counter-rotation effect by the extruder as it turns. Could this be the cause of the artifact?

@ origami: the carriage is pretty light, due to the flying extruder and i run very conservative acceleration. under certain cercumstances i can imgine a similar effect as an acceleration artifact but the spiral nature would still be weird.

@Kdog: what do you mean by counter rotation? if you mean the extruder swinging maybe, that would be more visible around corners not along a wall where the swing would continue in the same direction.

Quote
paboman

Quote
TheHebs
Generally its some type of issue like a wheel with a flat spot, or something snagging at a certain spot (filament, wires etc...)

reading on the web it seems to be a missing step that cause zebra stripes, i'm still unable to solve this

I found that my problem was caused by 1 faulty stepper driver.