How to tune/calibrate heater feedforward?
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RRF 3.4 has a new feature, heater feedforward. How do I determine the heater feedforward value(s) I need to set for my machine (and given filament)?
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This is what I was told by DC42:
heat the nozzle and let the temperature stabilise. Then commence extrusion at a fast rate (as fast as the extruder can reasonable manage without skipping) and watch the temperature. If there is an initial drop, then increase the feedforward. What you are looking for is either the temperature remaining steady, or rising by a small amount followed by a drop below target of a similar amount. When extrusion stops the reverse will happen, i.e. with no feedforward the temperature will rise and then gradually return to target.
If you give that a try and it seems to work well I will add that to the M309 entry.
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What length of filament is enougth for this test?
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@demonlibra said in How to tune/calibrate heater feedforward?:
What length of filament is enougth for this test?
How much filament does it take at max flow to impact the thermistor reading?
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@phaedrux
I always assumed this feature would help with dual tool printers to heat up the idle tool from standby-temp to working temp before toolchange?
Being able to look ahead was the reason for the dual gcode stream concept? -
@o_lampe said in How to tune/calibrate heater feedforward?:
Being able to look ahead was the reason for the dual gcode stream concept?
One of the reasons.
The purpose of heater feedforward is to better maintain an even nozzle temperature in high flow rate extruders, by anticipating the additional heat needed when the flow rate increases, instead of waiting for the temperature to drop before power is increased.
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@phaedrux said in How to tune/calibrate heater feedforward?:
@demonlibra said in How to tune/calibrate heater feedforward?:
What length of filament is enougth for this test?
How much filament does it take at max flow to impact the thermistor reading?
Aluminum V6, heater 40 W, nozzle 0.4 mm, maximum flowrate around 10 mm3/sec.
