pressure advance is changing motion, not extruder, why?
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This seems like a counterintuitive implementation. You don't have to have slower motion to get good prints. Linear Advance is the identical compensation, but it acts on the extruder instead of the motion platform, and what you end up getting is standard 100mm/sec printing with quality that used to be reserved for <50mm/sec. I have first hand experience.
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Why do you say that it's changing motion? It should be changing extrusion.
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Because it is. 0_1538540920713_pressure_advance.gcode
Print this gcode after you're printer is warmed and homed and watch your printer.
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@phaedrux In the config.g file that came with the duet, the M572 was set on D0:1, maybe that's not right. it's possible D0:1 are actually X and Y, not the extruders. Could that be why it's happening?
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The D values should only refer to defined extruders.
https://duet3d.dozuki.com/Wiki/GCode#Section_M572_Set_or_report_extruder_pressure_advance
I'm familiar with the K factor test you're trying to use, but it might not be the best way to tune pressure advance.
Maybe give this a try.
https://forum.duet3d.com/topic/6698/pressure-advance-calibration
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@phaedrux whether or not it's the best way, it still is generating g-code of identical movements and the printer is moving differently with each line.
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Can you take a video of what you're seeing happen?
If you print an actual model with pressure advance enabled what happens?
Also, what type of extruder are you using?
Direct drive will need much much less than bowden tube.
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@phaedrux I can take a video. I'm using a Flexion. I know I don't need much, but I wanted to see what happens at different values, and that's what happens. Have you tried printing my attached file to see for yourself that the lines print at different speeds?
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@gnydick said in pressure advance is changing motion, not extruder, why?:
This seems like a counterintuitive implementation. You don't have to have slower motion to get good prints. Linear Advance is the identical compensation, but it acts on the extruder instead of the motion platform, and what you end up getting is standard 100mm/sec printing with quality that used to be reserved for <50mm/sec. I have first hand experience.
I can categorical say that pressure advance as implemented in firmware on the Duet boards does not alter XY motion, only the extruders. This is something that I have done a lot of work and testing on at speeds up to 300 mm/sec using multiple melt chambers. I'm using my phone right now so it's difficult to provide a link but see my blog which is linked to in my signature.
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Well, I'll take a video for you and you can categorically tell me why it's happening
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@gnydick said in pressure advance is changing motion, not extruder, why?:
Well, I'll take a video for you and you can categorically tell me why it's happening
Do that. And also look at the YouTube videos that my blog posts on pressure advance link to because they clearly show that print speed does not change. Maybe you have something else set incorrectly, like instantaneous speed change which can interact with pressure advance.
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If you have the extruder jerk set too low in M566 that can cause the acceleration to be limited when you enable pressure advance.
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@dc42 Bingo!! That was it! I had a sneaking suspicion that might be the case. Good job!