Pressure Advance seems to not be working.

DIY-O-Sphere

You can sent the command directly in DWC
M572 D0 S#.# (#, set the number for the value)
I would recommend to switch every 4-5 mm between PA 0 and current PA value +adding an amount.
Then it's easier to see the difference in direct comparison....
I have done that with a custom code in Prusaslicer.

That are values between 0,6 and 1,4

Samuel235

@DIY-O-Sphere - So something like the following:

0-5mm: PA 0
5-10mm: PA 0.2
10-15mm: PA 0.4
15-20mm: PA 0
20-25mm: PA 0.6
25-30mm: PA 0
30-35mm: PA 0.8
35-40mm: PA 0
40-45mm: PA 1

I have been doing it just one after another without a 0 between, I see what you mean now, it will enable me to check all the way through the range easily back to original. Thank you, will get that done now.

DIY-O-Sphere

@Samuel235 said in Pressure Advance seems to not be working.:

After the last cube I have got the following result (I still can't really see much of a difference, is the seam getting smaller high we go do you feel, if so maybe I just need to take PA up higher, it was 0.7

I have compared your last result with my first print, where Jerk was too high.
Looks pretty similar. So maybe the jerk is still too high?

In the lower area (PA 0.2-1.0) there is absolutely no visible difference. Then above 1.2 the extrusion begins to fail....

What is the gear ratio of the extruder?

Phaedrux

@DIY-O-Sphere said in Pressure Advance seems to not be working.:

Then above 1.2 the extrusion begins to fail....

The pressure advance retreat combined with the retraction may have pulled the filament up high enough to get stuck.

zapta

@DIY-O-Sphere said in Pressure Advance seems to not be working.:

I have done that with a custom code in Prusaslicer.

As a side note, the upcoming PrusaSlicer will make it even easier to set per height configurations.

alt text

Samuel235

@DIY-O-Sphere - This is a 4:1 ratio extruder

@zapta - That is such an awesome addition to the slicer!

DIY-O-Sphere

@zapta said in Pressure Advance seems to not be working.:

As a side note, the upcoming PrusaSlicer will make it even easier to set per height configurations.

That is exactly the way I have done it ....

DIY-O-Sphere

@DIY-O-Sphere said in Pressure Advance seems to not be working.:

That is exactly the way I have done it ....

And what is also awesome: If you save the project file as 3mf you will be able to take that as template, without setting up all layer changes....

Samuel235

Currently trying the print again with Jerk set to 800 rather than 1000

Samuel235

I still believe there is something causing PA to not take full effect, i don't believe there is much change on this new cube either. I've lowered my Jerk even more but the fact that I don't see much change at all up the seam, I don't believe its having full effect. Testing another cube now with a Jerk of 400.

Phaedrux

Lowering the jerk will limit pressure advance even more. Unless you're using a high gear ratio remote direct drive like the Zesty Nimble reducing the jerk isn't really necessary.

I believe you're using the Voron2 Mobius extruder? Which is 4:1?

I would think that a extruder jerk and acceleration in the 3000 to 6000 range should be suitable.

I'm using a 3:1 titan aero with 0.9 degree motor and I use 6000 max speed, and 3000 accel and jerk. Mind you it's direct drive, so my PA value is very low 0.03 to 0.05.

Earlier you said you tried values between 0.5 and 7. Did you mean 0.5 and 0.7?

If you went up to 7 and nothing change something is wrong. If you only went up to 0.7 you haven't gone high enough.

What does the Voron 2 community suggest for extruder value configuration?

SnakeSP

@Samuel235 I'm facing the similar thing.
My extruder is BMG with 3:1 ratio. Bowden 55cm.
Printed test cube with jerk set to 600 and PA set to 0.2 through 1.0 - got very minor effect.
Previous experiments with python PA test script showed effect with PA set to 1.6-1.65 which made my extruder sing with forward-backward-forward rapid move on every line.
Now i think about trying to set jerk to 0 and raise acceleration, as the formula in doc is: actual_extrusion_speed = requested_extrusion_speed + (K * current_extruder_acceleration), which makes me think the jerk should be minimal while acceleration should be high.

Samuel235

@Phaedrux I did mean 0.5-0.7 sorry. I'm currently getting the printer ready for the print I said I'm running so I will change some settings back now then. I will put the Jerk back to the original 8000 (this is the default for this extruder, the majority of the community are running this value, with PA), and will change my test to range from 0.8 to 1.5 to see if I see any changes there.

How does that sound, too much or still too little PA?

Phaedrux

@Samuel235 Ok that makes some more sense then. 0.7 may simply not be enough.

Jerk of 8000 simply removes jerk from the equation, which is fine if the extruder motor can handle it rapid direction changes. This is a problem for the Nimble because of the high gear ratio and the high speed it would need to rotate and the back emf that results. But in your case I don't think it will be an issue at all. It may be a bit noisy though.

0.8 to 1.5 would be the logical next range to test with. 650mm bowden tube is fairly long, so I would think closer to the 1.5 mark.

DIY-O-Sphere

My BMG was skipping at such a high jerk. And that will also result in an annoying nocking noise....

Samuel235

Printing now with a Jerk of 5000 to give the extruder some chance of not being the fault of the next print (I will see if I hear any skipped steps), PA ranging from 0.8 to 1.5 with 0 between every 25 layers. Will post back shortly when its all finished.

DIY-O-Sphere

@Samuel235
Just for information, what is the retraction distance and speed? Material?

Samuel235

@DIY-O-Sphere - Retraction is 4mm at 60mm/s with a prime at 30mm/s and with Rigid Ink ABS in Black.

Edit: Correcting a typo

Samuel235

This cube has come out with no visual difference up the seam again. I had the following PA values at the respected layers:

Layer   | PA Value
25      | 0.7
50      | 0
75      | 0.9
100     | 0
125     | 1.1
150     | 0
175     | 1.3
200     | 0
225     | 1.5

No change at all other than it stopped extruding a little for 6/7 layers during the 1.1 value set of layers (layers 125 to 150).

M122 for this print:

M122
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RepRapFirmware for Duet 2 WiFi/Ethernet version 2.03 running on Duet WiFi 1.02 or later + DueX5
Board ID: 08DGM-956GU-DJMSN-6J1F4-3SJ6N-1BNBF
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Tasks: NETWORK(ready,524) HEAT(blocked,1236) DUEX(suspended,156) MAIN(running,1668) IDLE(ready,160)
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- WiFi -
Network state is running
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How far before the seam point on each layer should PA start to kick in because its literally right on top of the seam that the extruder shows some movement for PA. It doesn't change at all for the corners, its one continuous extrusion from start of layer to the end of the layer. I'm not sure it should really be like that....

Phaedrux

How fast are you printing? Is Cura limiting your acceleration and jerk?