Pressure Advance Calibration
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@lhelge Yesterday's tests got me to Jerk E200 as ok, with 250 to 300 causing blobbing. E acceleration seemed insensitive to wide changes up to 2000. I arbitrarily have it at 1000 (my print accelerations M204 Pnnn are either 2500 or 4000 and both seem ok ). E max speed is 2400 which is only useful for retractions as I understand it.
Pressure advance is 0.11 secs from the calibration wall with speeds of 25 and 75 and did not seem to be too dependent on temperature in the 240 to 250 range. I was thinking to test some lower PA settings on actual parts as I guess the lowest PA setting that works is preferable and possibly near 0.08 might be ok
In the context is everything is dependent on everything else, Temp is 250 for PETG and Bed 70 though bed surface will be less (temp gradient over 2 layers of 4mm glass) so I will wind that temp up soon. I am trying to juggle getting to good settings vs printing real parts for the upgrade to my printers so at the moment good enough is where I am and perfection later.
Re slicer setting - I have been using Cura 3.5 for the last 2 weeks that I don't sufficiently understand yet. I have been through every setting but what happens under the hood is a mystery. I like Slic3r, the idea of KISSlicer (that I bought the Pro license for) but at the moment practising with Cura: What settings are you interested in - there are a large number - I guess it might have a "Share Settings" somewhere?
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@digitalvision said in Pressure Advance Calibration:
Here are measurements from three different step functions in extrusion rates:
How did you measure that?
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Where do I set the retraction in this script? I can't see it retracting at all and with a 85cm bowden tube I get massive overextrusion without retraction.
Edit: nvm I just needed high settings. I had to go all the way up to 0.7-0.9 to get good results.
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Thanks for the script! Please note, to use the gcode you should use relative extrusions using M83, otherwise nothing is extruded. I think slic3r uses absolute extrusion M82. If you copy/paste startup gcode this could affect the print.
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@imqqmi said in Pressure Advance Calibration:
Thanks for the script! Please note, to use the gcode you should use relative extrusions using M83, otherwise nothing is extruded. I think slic3r uses absolute extrusion M82. If you copy/paste startup gcode this could affect the print.
Slic3R can produce gcode with either relative or absolute extrusion. There is a check box under "Printer Settings". The important thing is that the slicer setting (and any other scripts) should match whatever the Duet is set to expect, which can be either relative or absolute.
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@digitalvision I just wanted to post a quick reply thanking you for this script. I wanted to try out pressure advance, but really had no clue whatsoever how to start calibrating it. With this script (and illustrated instructions), I was able to find that my direct drive titan extruder + e3dV6 benefits from a pressure advance setting of 0.09.
I thought that the number was a bit high for a V6 attached to the titan extruder (via a precision piezo orion), but I have to admit that the resulting improvement is easily visible.
thank you!
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Also found out about this script a few days ago and, man, was I wrong about the values I used. Turned out my Bowden setup runs best at 0.85, whereas I was using 0.2.
Rightly noted that under-extrusion should be compensated by nonlinear extrusion, not presure advance. These two features in combination doubled my print speeds while keeping the quality.
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How should I choose min and max speed for calibration script? Max speed is the overal speed(70mm/s for me) or outline speed? (42mm/s). Min speed correlates with jerk speed or ..? Thanks!
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Where is the link to the pressure advance test file?
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How do I read this result?
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@gnydick I would say that the range of PA values you used is still too low because it looks like none of the layers is continuously one thickness.
Manuel
Duet 3 6HC (v0.6) with RPi 4B on a custom Cartesian
with probably always latest firmware/DWC (incl. betas or self-compiled)
My Tool Collection -
@wilriker ok, thanks. Strange I need so much. I have a direct extruder with zero slack.
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How do you run the pressure advance test file? I see it's in python..Does it work similar to the linear advance website Marlin has where we can change the settings and it creates a .gcode file?
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It's nearly identical. Instead of building up vertically, the linear advance creates a single extrusion on the bed for each setting and labels it.
You have to run the python program to generate the output.
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@gnydick I just figured out how to run it. I changed the filament settings in the file before running it which I expect has to be done. I guess just edit the gcode to set the print temperature and turn on relative extrusion?
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Will ask again... How should I choose min and max speed for calibration script? Max speed is the overal speed(70mm/s for me) or outline speed? (42mm/s). Min speed correlates with jerk speed or ..? Thanks!
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@briskspirit I'd simply go with minimum and maximum speed that I'd ever use on the printer. It's not so much about speed as pressure management in extruder. I ran the script at 60-120 first and 30-200 later once basic kinks were ironed out. The speed difference should be enough to cause significant pressure differences.
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Hi, I've been reading this thread for a long time and I noticed that a lot of people, like me, are having problems to identify the best PA in their tests. So I tried to create a similar script that tries to give clearer results. I am no sure if I achieved my goal
, but I decided to share it anyway: https://www.thingiverse.com/thing:3442071All the instructions are in the Thingverse link.
Here is one of my prints using PA from 0 to 3. Yeah, I need to use really high values. I didn't completely understood why but my Capricorn (original) bowden tube is big, so maybe I need to shorten it.
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i tried to print this, and nothing came out...
