I’m fighting wavy walls after corners, see this picture for a worst case szenario. I printed dozens of this samples with different settings in the last days:
I know, first thing everyone would think about is corner ringing. This would be due to the “shock” that’s created during the direction change and the axis is swinging after this. But that’s not the case. If anyone has an idea, especialy if he uses a simmilar setup and has no wavy walls, I would be very glad if you would read the following and comment!
I’m printing with PLA at 205° nozzle temperature, Openrail Mod on X and Y axis (no play!).
I did following tests to gather some informations:
- Print at 0.2mm layer height at different perimeter speeds (20-40-60-80): nearly 0 wavy walls at 20mm/s, increasing with speed. Maybe a little bit better at 80mm/s than 60mm/s. So 60mm/s is worst.
- Reorientate the part along the other axis: No change.
- Print at different accelerations (500, 800 and 1100mm/s²): Aprox. linear increase of the waves, as they also did in 1)
- Reducing current to the x and y steppers: No significant change.
- Add a flywheel with different mass to the Y stepper, printing the part in X and Y orientation: No changes between 0g to 50g.
- Printing at same speeds as in 1) but at 0.1mm layer height: Much better!
- Disable my advance feature (which leads to higher extrusion speeds during acceleration): Better.
- Braking the belt idlers during printing with my fingers: No change.
- Apply pressure (weight) to the print bed or the print head at different angles during the print: No change.
As a last test, I printed a single perimeter wall to see if the waves are due to swinging print head 90° to the print head or if the waves are changes in line width in reality:
As you can see, as suspected, the width is changing, creating the waves. So it should be due to inconsistent extruder flow or inconsistent x/y axis stepper speed.
My conclusion: I don’t believe it’s some kind of resonance, vibration or speed inconsitences of the x or y stepper because nothing from my tries that should change the vibration or speed behavior changed anything to the print. But there are significant changes in my experiments when the flow rate was changed as in 1, 6 and 7.
That’s why I think it might be some kind of flow rate pulses due to friction in the hot end, likely in the area of the heat brake, melt chamber and nozzle. The bad thing: If that’s right, the only way to prove this would be to buy another hot and, maybe an e3d one…
What’s your opinion, do you find a mistake in my tries or conclusion? Any other ideas what could be tested? Realy, any hint is much appreciated!