Artefacts on walls

dc42

What type of printer is it, which firmware version are you running, and what is your extruder steps/mm ?

Veti

its a Hypercube Fusion CoreXY with linear rails.
Duet Maestro with Firmware Version: 2.02(RTOS) (2018-12-24b1)
Extruder Steps are 415 for Bondtech BMG

dc42

I'm not and expert on CoreXY machines. I've seen a number of threads about similar artefacts on CoreXY machines. AFAIR the pitch of the artefacts generally matches the belt pitch, and the cause is generally friction. Using non-toothed idlers may also contribute.

Until you resolve this issue, I suggest you use spreadCycle mode for the X and Y drivers, also run them at higher rather than lower current.

Veti

the steppers havent arrived yet.
but this seems to be a common problem
see these benchys from a prusa.
https://youtu.be/FAXUjZZER5E?t=563

Phaedrux

@veti said in Artefacts on walls:

the steppers havent arrived yet.
but this seems to be a common problem
see these benchys from a prusa.
https://youtu.be/FAXUjZZER5E?t=563

That looks like plain old ringing to me though.

Veti

ok my 0.9 stepper motors arrived.

Looks ok from this angle

Same Cube, different angle, but still a lot better than before

However now i am getting layer shifts (as seen at the bottom layer), so i have to do some more tuning.

Veti

the layer shifts were due to the lowered stealthchop -> spreadcycle switchover.

its not that important but i think it would be more consistent to specify the V Parameter in M569 as mm/s rather than clock cycles

dc42

@veti said in Artefacts on walls:

its not that important but i think it would be more consistent to specify the V Parameter in M569 as mm/s rather than clock cycles

Then we would need to reprogram the stepper drivers when you set the steps/mm. So I compromised with setting the TPWMTHRS value but reporting the corresponding speed too. Also bear in mind that these are belt speeds, which for CoreXY, delta. SCARA| etc. printers are not the same as head speeds.

Veti

so i bought an ender 3 on sale and was surprised to find the same artefacts on the wall. I have not done much tuning on the machine yet.
This is using a board with marlin 2.0

so am i beeing to picky and there are inherent artefacts for 3d printing?

dc42

I can think of three likely causes of artefacts like that, that go all the way across the face (not just at the leading edge, which is symptomatic of ringing):

Belt issues. If that's the case then the pitch will be related to the belt tooth pitch and will not vary with layer height or extrusion width. A possible cause is the use of smooth idlers instead of toothed ones.
Motor issues (least likely). In this case the pitch of the artefacts will be a multiple of full motor steps, most likely it will be 1, 2 or 4 full steps.
Extruder issues. In this case then the pitch will decrease if you increase layer height or extrusion width. A possible cause is the use of an ungeared extruder with low steps/mm. Remedies include increasing extruder microstepping, changing from a 1.8deg to a 0.9deg motor, or changing to a geared extruder.