Pressure Advance and Retraction Settings Question



  • I had no idea this was hidden in the firmware, but it's exactly what I need:

    https://duet3d.com/wiki/Pressure_advance

    The question is, what would be some good settings to use on a Max Metal / Rostock Max printer with Capricorn XS tubing and approximately 2.50mm of retraction?

    I've had problems with blobbing and I think I can use this setting instead of Coasting and Wipe Distance to minimize this?

    I'm planning on starting with the 2.50mm of retraction, removing my Coasting and Wipe Distance settings and using the following in firmware:

    [c]M572 D0 S0.1[/c]

    Is that a good starting point or does anyone want to share their settings with a similar setup?

    • Thanks

  • administrators

    Yes, that's a good place to start, or you could try 0.05 because with the Capricorn tubing you probably need less than with regular tubing.

    One way to calibrate it is to print a cube in vase mode and look at the corners. If the corners bulge, use more pressure advance. If they get cut, use less. You can change the pressure advance on the fly while you are printing the cube, but the effect may be delayed a few moves.

    When you have tuned the pressure advance like this, you can do a regular print and reduce the retraction until the onset of blobs at the start of travel moves.



  • Mine is a completely different set up but when I tried, I needed much more - in the region of 0.5 worked best for me but that might just be something specific to mixing hot ends. My method of finding the setting that worked for me was a lot different too. I elected to print an object with long moves at highish speeds and observe any under/over extrusion issues at the start and ends of the moves. My reasoning being that those are the circumstances where pressure build up is more likely to manifest itself. Each to their own though….....



  • @dc42:

    Yes, that's a good place to start, or you could try 0.05 because with the Capricorn tubing you probably need less than with regular tubing.

    One way to calibrate it is to print a cube in vase mode and look at the corners. If the corners bulge, use more pressure advance. If they get cut, use less. You can change the pressure advance on the fly while you are printing the cube, but the effect may be delayed a few moves.

    When you have tuned the pressure advance like this, you can do a regular print and reduce the retraction until the onset of blobs at the start of travel moves.

    I have a part I've been making multiples of, so I'll try the 0.05 option and keep bumping it up until I hit the right balance.

    I think Coasting and Wipe function in a similar manner, except not tuned to the specific volume of plastic being extruded.



  • @dc42:

    Yes, that's a good place to start, or you could try 0.05 because with the Capricorn tubing you probably need less than with regular tubing.

    One way to calibrate it is to print a cube in vase mode and look at the corners. If the corners bulge, use more pressure advance. If they get cut, use less. You can change the pressure advance on the fly while you are printing the cube, but the effect may be delayed a few moves.

    When you have tuned the pressure advance like this, you can do a regular print and reduce the retraction until the onset of blobs at the start of travel moves.

    I had 2.50mm retraction and 0.15 pressure advance and I think there's a tradeoff between pressure advance and retraction because I think it got stuck in the cold zone for a moment and the print starts to layer shift when it frees up from the extruder.

    Is it something like 0.05 pressure advance to 0.50mm of retraction perhaps? I'm going to try reducing retraction by that amount as I increase pressure advance until I can reach a nice balance.


  • administrators

    The trade-off depends on your printing speed. The theoretical value is:

    Equivalent retraction = pressure advance * filament speed

    Where filament speed is approximately printing speed * extrusion width * layer height / filament cross sectional area.


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