Issue tuning pressure advance
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Physical setup: E3D ToolChanger with direct Hemera extruder, PolyMax PC @ 285C.
RRF 3.4.0, input shaping and nonlinear extrusion off (should be, not configured - will check)
I am tuning pressure advance using the python script - that part is working - the print is changing as the Z axis gets higher - for example, when pressure advance is too low, there are the expected holes where the nozzle is accelerating. The pictured sample is from 0.0 to 0.2. I've gone 0.0 to 1.0, and it starts to totally fail just beyond 0.2.
However, on every acceleration and deceleration, there is a thin spot regardless of the pressure advance setting. What's weird is that it is on both sides - I'd expect a thin spot on accel and a thick spot on decel with PA too low, and the opposite with PA too high. I can't think of anything that would cause this. I tried tightening belts as well - they're tightened up to 8lbs.
What is interesting is that this doesn't happen nearly as much with my bowden extruders - it is like there's some bug or issue or missing tuning feature in RRF that is being covered up by the slow response of the bowden extruders.
Any suggestions?
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Input shaping was actually enabled (Input shaping 'zvd' at 50.0Hz damping factor 0.10, min. acceleration 10.0, impulses 0.334 0.822 with durations (ms) 10.05 10.05) - I am re-running the test.
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Things improved greatly with input shaping disabled. How do I properly tune input shaping? I don't have an accelerometer.
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@jschall said in Issue tuning pressure advance:
How do I properly tune input shaping? I don't have an accelerometer.
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@phaedrux so, accelerometer required? No way to tune without? Where do I buy one compatible with my duet 2 wifi?
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@jschall See the last line of the document post above:
A ringing test print works well and you can change the shaper being used every several layers on the fly by sending a new M593. A good test print STL can be found here,So basically you can use the above test print to try different shapers and different frequencies. The klipper documentation provides some interesting information on how to estimate the ringing frequency etc. https://www.klipper3d.org/Resonance_Compensation.html
It would be interesting to see how you get on. There seem to have been a number of reports of how input shaping and pressure advance interact. Perhaps you could post samples of how things looked with just pressure advance (or even with both turned off)?
