PID hotend tune invalid at higher speeds
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I have run into an interesting issue. My PID tune is valid for regular printing speeds on my Mosquito Magnum+. But when I try and increase the speed above 400mm/s, the PID tune seems to not be able to keep up with the amount of filament being pushed through the system.
Is there a way to have different PID tunes, depending on the movement speed that will be performed?
Duet firmware 2.03 on Duet 2 Clone
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@dportero said in PID hotend tune invalid at higher speeds:
the PID tune seems to not be able to keep up with the amount of filament being pushed through the system.
What do you mean by that?
Duet firmware 2.03 on Duet 2 Clone
You really should update to 3.3.x or 3.4.x
Frederick
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@dportero RRF3.4 has heater feed forward so it can compensate for the temperature drop at high floor rates. There have also been other changes to the PID system in the recent updates.
It's a bit of a change to go the RRF3 as some of the syntax is different, and you'll have to update the firmware in stages, but I'd say worth it
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@engikeneer Unfortunately updating the firmware is not an option at the moment, as the printer I am using is the test machine for a larger print farm, so I have to keep it the same as the other printers. Is there nothing applicable for the firmware it is currently running?
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@dportero said in PID hotend tune invalid at higher speeds:
@engikeneer Unfortunately updating the firmware is not an option at the moment, as the printer I am using is the test machine for a larger print farm, so I have to keep it the same as the other printers. Is there nothing applicable for the firmware it is currently running?
PID tuning is done without any filament being pushed through the extruder so there is not as much heat loss.
The additional heat loss when actually printing may explain the issue you are having.
If might be possible to run PID running with the extruder going as well - I've never tried it but you could test it. You wouldn't need any XYZ movement.
Frederick
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@dportero well you could try manually tweaking the parameters from the heater tuning to try and get a tune that works better at the higher speed, though this may mean it is less stable or overshoot at lower speeds.
Probably worth trying to identify what is causing the temperature drop too. Is it from melting that much filament, e.g. try extruding that volumetric flow when stationary? Is it from the air flow during movement, e.g. try moving at 400mm/s? Is it from the cooling fan kicking in at a higher rate?
You could also try fitting a silicone sock if you haven't already?