Issues with pressure advance since RRF 3.4
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@Argo Was the Klipper setup using the same speeds/accelerations as your RRF configuration? Have you printed the test using the same filament? It really is important to try and keep as many things the same if possible. I suspect that PA values do not map 1:1 between Klipper and RRF. I think if you really want to rule out hardware you probably need to connect the extruder directly to the main board (because that way you can use both Klipper and RRF with the same hardware), but I can uderstand why that would be a total pain....
If you are going to test further I'd suggest getting the Klipper setup as good as you can (probably without input shaping for now). Then once you have what you think are two setups that are as close as possible to each other and you think there is a significant difference between them, ideally using the same filament, gcode settings etc, post photos of both along with the klipper and RRF configurations and slicer settings. Hopefully @jay_s_uk can have a go at reproducing the problem as he has a setup that can be switched between RRF and Klipper pretty easily. I think for this test it might be best just to use a single PA setting for RRF rather than the dynamic stuff that gives better results.
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@Heartleander81 Yes please start a new thread and provide details of what you think the change is, though honestly if there was a change in something like this I would have expected to see lots of comments about it already....
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@gloomyandy its probably the change between stealthchop being default to spreadcycle being default...
and I better run some more tests. @Argo do we have a consensus on the test piece? your one with curves and a square in the middle or just a 40 x 40 x 2 cube?
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I've made a more efficient version of the model to save time and filament:
I would set the seam to rear. Otherwise it'll be at one of the corners.
@gloomyandy
Yep it's a total pain as I would need to rewire all the chains. My Klipper test was just a dirty hang all wires along the frame to the top and to the tool head method. And during the test I held the wires to they don't get caught lol. -
@Argo Does that mean you can't easily run any further Klipper tests?
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I can but not for weeks as it’s quite the mess here and not really safe to print unattended.
I can print the test again with adjustments to flow and PA. I’ll post the results soon.
Inputshaping does not decrease print quality with Klipper as long you stay within the recommended acceleration settings. -
@Argo I'd rather you keep input shaping off with Klipper (and with RRF) as that just simplifies things (as it does seem to have an impact on RRF).
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Bumped PA up from 0.05 to 0.052. I think maybe 0.054 could be the optimal value.
Decreased flow a tiny bit to improve top layer quality.
(Klipper)The result is quite comparable to what I get with RRF with "dynamic PA" (0.05 -> 0.08).
Sorry that I had to switch color. The bright green is empty after tons of testing. -
@Argo No problem, could you post your klipper and slicer settings (maybe post the gcode file you used with Klipper as that will have a lot of the details in it).
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For Klipper itself nothing fancy.
square corner velocity = 5 mm/s
max feedrate = 350 mm/s
max acceleration = 5000 mm/sSlicer speed settings:
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Been following this thread for a while now,
, and wondering if there's been any concrete, official update? -
Latest official statement is that the Duet team can't reproduce the issue so I assume there won't be a fix. That's why I'm glad I found a partial fix by using Super Slicer extrusion roles:
https://forum.duet3d.com/post/298231
At the moment I'm using 0.052 PA for every role except perimeter which use 0.075 PA (PLA filament). -
@Argo said in Issues with pressure advance since RRF 3.4:
Latest official statement is that the Duet team can't reproduce the issue so I assume there won't be a fix. That's why I'm glad I found a partial fix by using Super Slicer extrusion roles:
https://forum.duet3d.com/post/298231
At the moment I'm using 0.052 PA for every role except perimeter which use 0.075 PA (PLA filament).As you found, that isn't great though, since the change in PA causes the printer to dwell.
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From my own testing a while ago I had noticed a difference in extruder jerk when I was getting some bulging corners. After retuning E jerk and PA it improved.
Has anyone noticed a difference in E jerk?
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@Phaedrux possibly. It at least seems to be very sensitive to it. Right now, with even just a low poly curved surface, each segment is ~1.5mm long, I get a bulge at every direction change.
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Yes, definitely.
If I increase or decrease the extruder pressure, I can influence whether there is more or less overshoot. But I can't get rid of it completely. -
Yes it’s far from optimal. But at least parts are usable again. Though I had Klipper flashed and it hasn’t the flaws I’m not really into using Klipper. Just a personal preference. But wouldn’t wonder if someone switches because of that.
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I will only use it as an emergency backup. Sure if RRF fits again I'll switch back, I think. I'm already a fan of Duet.
But to test whether my hardware fits, I'll try Klippers. The last parts will arrive in the days for the test with me. -
I don't know if this helps but I decided to run some tests. Two printers were used to compare the output. One is a CR10-S5 and one is a Jubilee printer. The CR10 is running a Duet2wifi and a Duex5 expansion card, the Jubilee is running a Duet3-6HC with the extruder being run off a tool board.
In both cases the extruder is a direct drive extruder. Both use firmware 3.4.0.
I used a pressure advance python script that I plugged the correct data into in order for it to generate a gcode file. The file prints a single line with fast and slow segments. Slow segment was 5 mm/sec, fast segment was 100 mm/sec.
The same filament (same roll) was used in both cases.
It probably has been well over a year since I last ran this pressure advance test but it used to show very clearly what the pressure advance should be set to.
I can report that the result was absolutely useless - there was no discernible difference in the layer lines. I ran pressure advance from 0.000 to 1.000 just to cover my bases but did more in-detail testing in the 0.000 to 0.080 range which is the expected range for a direct drive extruder.
There was an occasional abnormality here and there but it was not consistent and certainly was not repeatable.
I have set config.g on both printers to 0.01 as a wild guess. I could have chosen pretty much any figure between 0.00 to 0.08 as the test print showed no difference in the output.
When I was getting close to 1.0, I was seeing some issues but again, there was no clear 'this is good' and 'this is bad'.
I am left with two possible alternative explanations: 1) I don't know what I am doing or 2) PA is completely and utterly borked.
Since these tests have been a good indicator for PA before, I am leaning towards #2.
In all fairness, it did take me some time to tweak the python script to work with a multi extruder printer which initially also caused no change in the printed output. That was caused by me printing with extruder 1 but setting the pressure advance for extruder 0 ... doooohhhh ..... but I did correct that and feel that I have valid gcode files and pressure advance is simply not working. I have run M572 on the active extruder and as far as I can tell, the printer thinks it is set to the right pressure advance. -
@jens55 What was the version of firmware you were using when this test worked? Has anything else changed in your printer setup (hardware or configuration) since then?
If you think this is a problem with 3.4 that did not exist on an earlier version please switch back to that earlier version and publish the results from both. So far I do not think we have any examples that show this is a change between versions of the firmware (when using the same settings and hardware for both new and old versions). If you are using any 3.4 features (like input shaping), you may want to try disabling them and re-run the 3.4 test again before switching back to the older version.
