RRF 2.03 pressure advance causes 20% overextrusion
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@bot
Will check now.Printing 2 cubes did not cause overextrusion...
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I'm really surprised there's no counter anywhere for total steps taken on each drive. Maybe I should try to add that (would have to work out how to build).
Alternatively I can hook up a logic analyzer and have it count the steps...
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Logic analyzer capturing, wrote a python script to analyze the results, running the file with pressure advance now, then I'll run without.
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Why 8x microstepping on the extruders?
M350 E8:8:8:8 C8 I0
What are the actual extruders?
M566 X500 Y500 Z60 C2 E800:800:1200:1200 ; Set maximum instantaneous speed changes (mm/min) M203 X35000 Y35000 Z1200 C5000 E2000:2000:2000:2000 ; Set maximum speeds (mm/min) Your max speed is a bit low and might be limiting your retraction speeds.
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@Phaedrux said in RRF 2.03 pressure advance causes 20% overextrusion:
Why 8x microstepping on the extruders?
M350 E8:8:8:8 C8 I0
What are the actual extruders?
M566 X500 Y500 Z60 C2 E800:800:1200:1200 ; Set maximum instantaneous speed changes (mm/min) M203 X35000 Y35000 Z1200 C5000 E2000:2000:2000:2000 ; Set maximum speeds (mm/min) Your max speed is a bit low and might be limiting your retraction speeds.
8x microstepping on extruders would be the default setting for E3D's toolchanger, I haven't touched that.
The extruders are E3D titans.
I reduced maximum speeds because I was starting to get skipped steps when commanding high speeds through the interface.
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Does Duet configure the trinamics in rising edge or falling edge mode?
With PA at 1.0, as counted by a python script analyzing the output of my Saleae (assuming rising edge mode):
fwd_count 6334445
rev_count 5157566
net_count 1176879
mm 2979.440506Slicer says 2.48m filament use. Duet web interface confirms, says the file has 2481.7 mm filament use.
Next up, PA at 0.0. If this comes out correct, it will be incontrovertible proof that there is a firmware issue with PA causing overextrusion.
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The python script: step_counter.py.txt
The data with PA: https://drive.google.com/file/d/16LW2Xb2MWsUTvyCdSjDqBvFwDXq1xOuR/view?usp=sharing -
Ah, the TMC 2660 doesn't have a falling edge mode, only rising edge and both edges. I misread the datasheet.
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With no pressure advance: https://drive.google.com/file/d/1oFvrJnxZc6fvLlGZqTdCqO7GB4Zfzdy_/view?usp=sharing
Python script output:
fwd_count 1942964
rev_count 961423
net_count 981541
mm 2484.9139242.48m, dead on what the slicer expected.
Proof positive that PA causes overextrusion and that this is a firmware bug, NOT a mechanical or configuration issue.
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@Phaedrux said in RRF 2.03 pressure advance causes 20% overextrusion:
Why 8x microstepping on the extruders?
What is recommended?
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x16 with interpolation enabled.
also your thermistor config is wrong.
Your bed is 4138 which is the default and very likely wrong.
Your hotends are 4388
So you might be printing at the wrong temperature.E3D uses 104-GT2 thermistors which is B4725 C7.060000e-8
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@Veti said in RRF 2.03 pressure advance causes 20% overextrusion:
x16 with interpolation enabled.
also your thermistor config is wrong.
Your bed is 4138 which is the default and very likely wrong.
Your hotends are 4388
So you might be printing at the wrong temperature.E3D uses 104-GT2 thermistors which is B4725 C7.060000e-8
Set to 260C/120C. Seems fine to me.
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I've done more research and 4725 is the wrong B value. The right number is 4267. I might update my config to match, I don't fully trust the thermal camera's accuracy and it doesn't make sense that the hotends and bed are different when the bed uses the same thermistor.
But I'd need to do some verification on that change regardless.
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Regarding underruns: I'm running the file again now to determine if there are any, but it is most of the way through and there have been no underruns.
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@jschall said in RRF 2.03 pressure advance causes 20% overextrusion:
I've done more research and 4725 is the wrong B value. The right number is 4267.
No its B4725 and C7.060000e-8 if you Specify B and C you switch to the Steinhart–Hart equation which is more accurate over a wider temperature range.
This is documented here
https://duet3d.dozuki.com/Wiki/Connecting_thermistors_or_PT1000_temperature_sensors -
@Veti
Thanks, will correct that, then. -
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Well, this is interesting thank you for doing this.
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@bot said in RRF 2.03 pressure advance causes 20% overextrusion:
Well, this is interesting thank you for doing this.
Any suggestions where to go from here?
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please do upgrade to the latest firmware.
even if there is a bug in 2.03 i doubt that we will see a rrf2 bugfix.
so it would be good if you could retry this in rrf3.