Pressure advance possibly not working correctly
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I've tuned my machine using the PA calibration python generated model. I find my perfect value, and every model I print has big holes at the start/end point on the perimeters. I know the suggestion is to reduce the amount of retraction used, but I'm only retracting 1mm and it's set to only retract when crossing perimeters, so I don't think it's retracting at all ON the perimeters.
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@gnydick Are those 2 points indicated in the picture the only areas where the problem exists? If the problem is as you describe, then surely it would affect the entire print. I'd be more inclined to suspect a problem with the gcode of the model itself.
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@gnydick If you turn off pressure advance while printing the exact same gcode file, the problem doesn't appear?
"I'm not saying that you are wrong - I'm just trying to fit it into my real world simulated experience."
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What PA value are you using? I found that if I don't crank the extruder jerk all the way down from 4000 to 500 with a PA value of 0.4 or higher, then during some moves there were such "Insane Extruder Step Variations"
that the steppers started losing steps and I'd get holes or overextrusion. The Python script does not test for this and most simplistic models ran fine, but as soon as curves and many small perimeters went into play it just went to hell. -
@edgars-batna just .1
I wasn't getting any sort of skipping. I have direct extrusion, so for me PA is really only about changes in speed, and not also making up for bowden latency.
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@deckingman they're all over, but my seems are not always in the same place, so I'd have to rotate the printed model to show you all of them.
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@garyd9 I'll try that and let you know
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@garyd9 I tried it and they're still there. That's odd because it's only a couple mm of retraction.
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@gnydick said in Pressure advance possibly not working correctly:
@garyd9 I tried it and they're still there. That's odd because it's only a couple mm of retraction.
If you turn off pressure advance and the problem still exists, it strongly suggests that pressure advance isn't the issue. (Are you 100% certain that pressure advance wasn't enabled? The best way to be sure is to run M572 from the gcode console while a print is running and verify that the returned value is 0.00.)
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Hi @gnydick , could you please post some gcode that has this problem. Thanks.
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Layers look thicc, .8 nozzle?
Every machine I've used with a .8 or larger exhibits this issue.
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@wyvern yes, .8 nozzle. That could be it.
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@gnydick I don't know how to fix it or what it is, but it shows on tight curves.
.6 is usable for general use, I use .8 for simple geometry parts that need to be strong. -
@Wyvern @gnydick Mabye is it too thin walls for normal 0.8 print - Depending on the slicer, make sure to have "thin walls" or whatever it is called in your slicer to on -
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@martin1454 thanks
