Pressure Advance - related settings



  • I am going to try using pressure advance for the first time. Planning to test starting with range 0.05 - 0.15 "on-the-fly" with panel due.
    Below are my current typical settings. Wondering if I could get some advice on how these might be changed if using pressure advance. Use S3D.
    Have Folger Tech FT5, E3D Titan extruder, direct feed, Volcano w/0.4 nozzle.
    My typical printing:
    ABS, 245-255C, bed110C, 0.2layer, speeds 60-80+mm/sec, 0.2 layer, 25-90% infill, 20-30% outline overlap.
    Retraction usually 0.3-0.7mm, no extra restart, lift 0.15mm, retract speed 60mm/sec.
    Rarely use coast but sometimes at about 0.3mm.
    M566 X800.00 Y800.00 Z30.00 E1000.00 ; Set maximum instantaneous speed changes M203 X9000.00 Y9000.00 Z2000.00 E4000.00 ; Set maximum speeds (mm/min)
    M201 X1000.00 Y1000.00 Z500.00 E1000.00 ; Set maximum accelerations (mm/s^2)

    Any feedback appreciated. Thanks much.



  • @danl said in Pressure Advance - related settings:

    Planning to test starting with range 0.05 - 0.15 "on-the-fly" with panel due.

    Any reason why you don't use a pressure advance calibration script?



  • Might wanna give these a try if you plan on live tuning with the PanelDue.

    https://forum.duet3d.com/topic/6181/tuning-macros-menus-accel-jerk-retraction-pressure-advance

    The only thing I would change is your extruder jerk and acceleration, I would increase them by a few thousand in order to allow pressure advance to move as needed.

    @danl said in Pressure Advance - related settings:

    Rarely use coast but sometimes at about 0.3mm.

    Don't use coast or wipe with PA. PA should be able to negate the need for either.

    @zapta said in Pressure Advance - related settings:

    Any reason why you don't use a pressure advance calibration script?

    I prefer to live tune as well. I find the script too artificial.



  • @phaedrux said in Pressure Advance - related settings:

    I prefer to live tune as well. I find the script too artificial.

    How is it done 'live'? Do you use a special model? How do you tell if things get better or worse? What do you look for?



  • @zapta
    I'm not that sophisticated a user yet. Just looking at a simple first test run to see the effects of changing PA. Pic shows what I looked for....artifacts on surface of a cylindrical object...an initial priority for me.
    @Phaedrux
    Thank you for your always detailed evaluation and feedback.
    I will increase the E jerk and accel.

    Pic shows results...PA is a pretty cool. I'll re-test on a simpler model with other settings soon, but I now have an idea of how effective PA can be.
    The 0.02 PA gave a result well within my acceptable range, and definitely better than I've had previously. May not show in the pic, but the seam is narrow and very smooth. The endpoints were aligned just to more easily see differences.
    0_1564492112612_pa pic.jpg



  • @zapta said in Pressure Advance - related settings:

    @phaedrux said in Pressure Advance - related settings:

    I prefer to live tune as well. I find the script too artificial.

    How is it done 'live'? Do you use a special model? How do you tell if things get better or worse? What do you look for?

    What works for me is to print a big rectangle at the highest print speed I know my hot end is capable of without any under extrusion. I do it with 100% infill and observe the beginning and end of the infill lines. Without pressure compensation, what happens is, at the end of a move the print head decelerates but because of the pressure build up in the extrusion system, the rate of deceleration of the filament is much less than the carriage. So you get over extrusion at the end of the line. Conversely at the start of a move, the print head accelerates and so does the extruder but the filament acts like a sponge. So you get an increase in pressure but it takes time for that to translate into more filament being forced out of the nozzle. So you get under extrusion at the start of a line. The higher the acceleration and print speed, the more pronounced the effect will be. It also takes time for the pressure to build up so short moves won't show the full effect of pressure. Hence a large cube at high speed. Using 100% infill gives time to evaluate several different values. If you can't establish the value in one layer, print several layers at slow speed to establish a nice flat base, then try high speed again. Once you have the correct value, re-tune the retraction.

    For observation of the line ends, I find a finger tip offers a more sensitive measure than an eyeball.



  • @zapta said in Pressure Advance - related settings:

    @phaedrux said in Pressure Advance - related settings:

    I prefer to live tune as well. I find the script too artificial.

    How is it done 'live'? Do you use a special model? How do you tell if things get better or worse? What do you look for?

    I use a technique similar to that described by Deckingman above, as well as a model that has identical layers all the way up so that you can compare different value ranges in a single model. Much like the cylinder that DanL shows in his picture, but I also try and use a more complex compound shape that has curves, hard corners and longer extrusion sections. Also, when I get tired of printing boring calibration objects I print other detailed models and tweak it as needed. I don't have a long bowden, so the amount of PA needed isn't much, and for me only varies from 0.025 to 0.05. I don't envy users of long bowden tubes.


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