Erratic movement of head

I am still practicing greyscale gradients. But I wonder, is it normal for the head to move this erratically?
I was expecting a smooth movement…

Hmm, movie does not move :wink:


That’s incredibly common if your controller isn’t fast enough to keep up with the fire hose of gcode being sent to it. What speed and DPI did you set this to?

At 100mm/sec, and 254 DPI, you’ll send 10 gcode instructions per mm of image, and would need to process 1000 of them per second to maintain that speed at that DPI. Most 8 bit controllers can’t do this. 32 bit controllers are generally faster, but if they have a short plan buffer they might no be able to see far enough ahead, and will limit the maximum speed to allow them to stop in time if the next move in the buffer is a full stop or reversal. Having a larger plan buffer or using higher acceleration will help that, but may cause other issues.

What Firmware is this machine running?

Click on any users name to expose the following.



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Excuse my late response. It looks like I do not get reliable notification of responses to my own posts.

I am using a Maestro indeed, so it is 32bit.
Not really sure during making of this video, but I think the speed was 2000 mm/min with an interval of .1 mm.

What strikes me in this behaviour, is that areas that are mostly black or mostly white do not show this erratic movent. It looks like only the mid-tone areas (where there is a need of more on/off switching) produce this effect. Is there a plausible explanation for that?

Yes, the first explanation I gave, in fact. At 50% gray, dithering produces a nearly perfect on/off pattern for every dot. In areas of mostly black or mostly white, the dots get much more spread out, so the shading in those areas takes far fewer gcode instructions to represent.

Okay, I think I understand that.
I am not sure if velocity ramping compensates for that. It does for acceleration, but I think it is best to not exceed the speed at which this happens.

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