Jerk/M566 how to find the ideal setting?
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Hi *,
I struggle a bit with finding the best jerg/M566 settings. I guess that I want to find the max possible values but I do not know how to find them. Any ideas/theories how to find them?
Cheers, Chriss
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@Chriss As a general rule, I get best results by keeping the print speed as near constant as possible, which means setting jerk as high as possible. The constraint is whether the mechanics of the machine can stand it. Try printing a largish hollow rectangle with increasing jerk. You'll get to the point where there is a noticeable "clonk" at every corner. Depending on how rigid the machine is, this "clonk" might be alarming if not damaging, so back off the jerk until the machine sounds "happy".
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@Chriss If you want to see the affect of changing a parameter over the course of a print, you can use the same macro method as shown in the input shaping tuning here: https://docs.duet3d.com/en/How_to_guides/Calibration#klipper-version
Ian
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My method for jerk setting...
I generally print a stepped series of radials (or a cone) and watch what the printhead is doing as it prints the outer radial. With jerk too low, you will see small corner artifacts on the outer wall and you will see & hear the printhead making abrupt movements. As you raise the jerk, the radial wall will smooth out and the printhead will move much smoother. I usually raise the jerk during the print using M566 in small intervals just to where the printhead/radial just starts to smooth out, and that setting seems to work great.
It also really also depends on how your printer does with resonance and whether or not you need input shaping. With less jerk, I find the input shaper tends to work a little better. Excessive jerk can also elicit resonances right after sharp corners.
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@br7408 that’s an interesting way to tune jerk. What printing speed and jerk setting did you end up with?
Ian
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@droftarts I found I was able to get it the smoothest right around minimum 600 jerk. Speed wise it obviously depends on the nozzle size and material, but with a .6 and ASA getting nice smooth outer walls around 160 mm/s with 36hz mzv on the resonance tower. Inside walls I can print up to 200. Accel generally around 4-6k.
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@br7408 Thanks... that sounds like a very cool way to find the right values. .... I will give it a try....
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@Chriss said in Jerk/M566 how to find the ideal setting?:
@br7408 Thanks... that sounds like a very cool way to find the right values. .... I will give it a try....
I literally reconfirmed this again yesterday.
I was printing a partially radiused object (120 mm fan shroud), and I figured I'd lower the jerk a little just to see if I could get a slower start on the straight edges, to help the IS work a little sooner. As soon as I dropped outside wall jerk to 540, I could hear the steppers ratcheting on radius moves, and the outside wall of the radius was choppy. Went back to 600 and it was fine again.
I think jerk is literally one of the only settings that my printer really can consistently tell me what the minimum acceptable setting is.
Now this is a 4 motor corexy.... I don't know if that would make a difference.
