Issues with pressure advance since RRF 3.4
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Quick update from my side.
I have concluded that this issue is definitely a filament behaviour / Pressure Advance component.
The largest improvement I have witnessed by tweaking every setting is to simply increasing the jerk value. I previously used a pretty conservative jerk of 4mm/s but with high accelerations 6000->12000mm/s^2. I have now changed the profiles to be of a much higher jerk 10->14mm/s with middling accelerations of 3000-5000mm/s^2.
This change overall has maximised the speed the nozzle can take the corners at, and thus has reduced the bulge amount considerably. The other change I have done is to manually change the STL files I use to round most corners by a minimum of 0.8mm in a bid to again, increase the overall speed the nozzle can take a corner at.
What I have found interesting during my testing is there seems to be a minimum jerk to acceleration ratio where if the nozzle cannot take a corner with sufficient speed. the outer layer quality on curved surfaces drops considerably (even with extremely high quality STL files and arc welder enabled). There is another thread that seems to be having the same issue: https://forum.duet3d.com/topic/33903/jerk-settings-at-different-speeds
Though, in order to keep this thread focused on the PA aspect (which I am now 100% certain there is) I will probably be creating a new thread for the Jerk/Accel behaviour oddities separately in the next few weeks while I gather more data.
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My slightly modified Creality 5 pro prints FLAWLESS prints in ASA within +/- .03mm, and perfect corners every time, and has printed several hundred of these prints for two years now in numerous sizes and detail; with no PA or IS applied.
I wonder what the true problem is here…
If you’re relying on current software to fully tune out harmonic and flow issues of your printer, you simply need to slow down your outer perimeter print speed and accept the limitations of your printer.
Without a full feedback loop of accurate algorithms, no current software will be able to adjust for all conditions and provide the accuracy that people seem to think is expected. What is happening instead is we turn into the feedback loop and chase countless inconsistencies.
You will be more successful and efficient resolving resonance/pressure issues by improving the physical design of the printer than you will be expecting software to resolve it.
I’ve been fighting this shit for over a year now, and I’m tired. I’ve finally figured out that simply slowing down outer perimeters, turning down PA and turning off IS & optimizing outer perimeter jerk/accel/speed gives me the best and most consistent print and I don’t need to re-tune for every nozzle size or material. Yes, its slower. Its also much less filament/nozzle dependent and more consistent. I can still print infill and supports at insane fast speeds to cut down on time.
If you really want super speed, buy a Bamboo and deal with their proprietary bullshit.
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Im not entirely sure what point you are trying to make here. But its definitely not on topic, nor is it helpful to identifying the cause and effect which causes these surface irregularities.
My slightly modified Creality 5 pro prints FLAWLESS prints in ASA within +/- .03mm, and perfect corners every time, and has printed several hundred of these prints for two years now in numerous sizes and detail; with no PA or IS applied.
Im happy that your machine works flawlessly for your use case and speed requirements, however this is the equivalent of saying "it works on my machine so it should work for yours"
A CR-5-pro is an entirely different class of machine compared to most people who are having issues. And comparing a Bowden system to a Direct Drive is already a stretch.If you’re relying on current software to fully tune out harmonic and flow issues of your printer, you simply need to slow down your outer perimeter print speed and accept the limitations of your printer.
The issue most of us are having is not flow issues, its flow control issues. I can happily print my outer walls at 100mm/s using only 30% of my nozzles max flow, but the issue still persists. Thats because its not directly a speed or flow rate problem. The issue still exists at 60mm/s or 40mm/s.
Just making a post about how "slow your machine down and you'll be fine" just derails the entire conversation and the research and identification that the other users in this thread are documenting.You will be more successful and efficient resolving resonance/pressure issues by improving the physical design of the printer than you will be expecting software to resolve it.
If you have any advice to give I would gladly welcome it. I am currently using a Hemera XS with a copper heat block using a CHT Volcano nozzle. I would like to think that my choice in nozzle, extruder and tertiary materials are all aiding in making a better printed output. I would expect most people in this chat are probably using different extruders, with different nozzles from various brands and qualities.
If you really want super speed, buy a Bamboo and deal with their proprietary bullshit.
I hope its not just me, but I find this defeatist attitude extremely offensive towards all the hard work Duet have been putting in to making their ecosystem, to any advanced user (Voron, VZbot, Etc) who spent lots of time and money to make a fantastic machine, or even to the other companies like Bondtech or E3D with their high flow hot ends or parts designed for higher grade machines than your creality 5 pro.
Your response is just "buy a Bamboo and deal with their proprietary bullshit".
Im sorry if this comes across a bit ranty, and you are correct in your statement that without full feedback, no software will be 100% able to compensate for every situation, but that doesn't mean we shouldn't try. Trying to improve stuff with the community is pretty much the definition of Open Source and everyone here is documenting their experiences in a bid to help reduce or mitigate the issue.
The real bamboo printer manufacturer
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Now that some steam has been blown off hopefully we can get back to the issues at hand. Thank you to all participating in finding the cause of the issues.
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Not sure why you seem to be so offended as my comments were not even a reply to your post specifically. I guess that is what the internet has become these days.
I feel it absolutely is on topic. The entire industry right now is using printing and movement speed as a selling point to their machines, and this entire topic is based on software algorithms that are implemented SOLELY to improve printing speed. My Creality 5 Pro is not a Bowden machine, as you assume. It is also only one of four printers that I own. I only use it as an example because it is the one machine that prints consistently with zero corner issues or resonance with zero PA or IS applied and it does this due to the specific reasons that I highlighted.
I have been tuning my Duet-based CoreXY printer for a very long time, using and implementing just about every approach possible, and with each approach, it always comes back to the same basic principle, which I adequately highlighted. Software is not going to make a machine faster when it has specific analog traits and limitations that vary beyond the capability of the software. Yes, it is fun to try, and yes, I can find one or two prints and apply a limited amount of IS and PA and eventually get them perfect... But when I go from a .6 to .8 nozzle and an entirely different material viscosity, or even filament brand... guess what... I need spend another 6 hours tuning IS, flow rate, PA, ect. to get that next print perfect, or I can just slow down and print it in 4 hours instead of 2 or 3 and already have been done with the print. Perhaps my view from a business owner standpoint is different because time to me is money.
You can try and speak for Duet all you want and become offended over some words. Quite the contrary to a defeatist attitude; my sole point is that one should be well aware of the limits of their machine and manage their expectations accordingly. The Bambu comment was because I actually am on loan with one right now to test and study. I am not a fan of proprietary machines, and never have been. The requirements of my business are well beyond the size capabilities of a Bambu. I do feel like they have gotten a few things right because this machine indeed uses feedback to adjust for changing analogous conditions per print and per material and the results are quite evident.
I can assure you the Duet engineers are studying the same technology as well and doing their best to determine future implementation. The bigger burden is on the Duet engineers to design an open source software that works across any machine, which of course is a much greater challenge, and I have nothing but commendation for Duet, Dave Crocker, and the hard work they have put in to meet customer expectations to date. I would not be in a Duet forum with over a thousand dollars invested in numerous Duet boards if I was not a huge fan of both their product and their work.
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https://forum.duet3d.com/topic/33803/unable-to-stop-severe-bulging-in-corners-with-new-print-head/29
The same issue in above link too.
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Most likely it is obvious on CoreXY machine. When there is a corner, and moving before arrived the end of corner, both A motor and B motor, need to slow down, severe bulging will come before arriving the corner. If it is the machine like UM, it will be only severe bulging after corner but never before corner, as there is only one aixs motor for each aixs. However this is the inherent feature for CoreXY, due to it needs both A motor an B motor keep moving.
This is the first time I am using CoreXY machine, the E3D ToolChanger.
No clue how to fix it...
What I guess, PA can't fix this, as it is XY movement related, not extrusion related. However the Input shaping is the direction. RRF Input shaping is still the blackbox, a long way need to go.
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Adjust the belt tension can not fix the problem.
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Someone shared me that, he has the same issue on RRF, however It comes to be fixed after he using the Klipper. Really no idea what's the diff.
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This problem can be replicated on Hbot and other similar Cartesian designs. Its only more obvious because CoreXY tends to have higher speeds thus requiring higher flow rates. Overall, its almost entirely a flow control issue instead of a kinematic issue.
Klipper has a feature called smoothing time which works with their pressure advance - My current belief is that this smoothing time is the key to fixing this issue. I am currently building a test machine that will use klipper for an apples to apples comparison between RRF and Klippers implementation. But ill be having to do it after SMRRF as time constraints are tight right now.
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@PCR so do I (actually capable of triple play -- Marlin, RRF, and Klipper). I can't say I have these issues with bulging corners but I run quite high extruder jerk and acceleration (https://forum.duet3d.com/topic/33964/e-acceleration-has-to-be-limited-to-to-e-jerk-pa?_=1700602309451). I wonder what e jerk and acceleration the people heavily affected run; if jerk and accel aren't high enough I can see that PA may kick in "late" and not have (any) effect, especially at higher speeds.
<>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>
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@oliof said in Issues with pressure advance since RRF 3.4:
@PCR so do I (actually capable of triple play -- Marlin, RRF, and Klipper). I can't say I have these issues with bulging corners but I run quite high extruder jerk and acceleration (https://forum.duet3d.com/topic/33964/e-acceleration-has-to-be-limited-to-to-e-jerk-pa?_=1700602309451). I wonder what e jerk and acceleration the people heavily affected run; if jerk and accel aren't high enough I can see that PA may kick in "late" and not have (any) effect, especially at higher speeds.
So first of all we need to stop tuninig anything but testing the capability of the E motor.
Btw, any steps or details shown how to find out the value? -
@hestiahuang I simply increased extrusion speed into thin air until the extruder skipped, then backed off of that 20%, after that did firmware retrac/unretract with increased acceleration until the extruder screamed, and then backed that off 20%
There is a case to be made that you may need to redo this for PETG due to its difference in backpressure behavior, but I never bothered and it seems to work well enough.
In direct drive, my PA value is 0.02 to 0.03 and that seems to be good enough.
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@oliof What extruder jerk are you currently running? After reading your other thread I tried increasing mine to the 3000 range (previously it was 300), but with that setting I started getting various odd noises at sharp corners and seemed to be losing extrusion.
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@gloomyandy jerk in the 300 to 600 range, acceleration in the 3600 to 6000 range
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@oliof Thanks, what sort of jerk and acceleration are you running on X, Y, Z? I must say I do find the entire jerk/acceleration thing very confusing having spent some time yesterday searching the forums it seems that values anywhere from high jerk/lowish acceleration to low jerk/high acceleration seem to be in use! There also seems to be some (unresolved) confusion as to when jerk is actually applied with some comments indicating it is only used between moves while others say it is applied (in mode 1) as an initial speed for moves that start at zero.
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@gloomyandy jerk is a bit of black magic, I spent a weekend with a friend trying to read and understand how its applied in RRF, but I forgot all about it since then.
my jerk/accel on the IDEX are
M566 X360.00 Y210.00 Z18 E300.00 P1 ; Set maximum instantaneous speed changes (mm/min) M201 X7500.00 Y4000.00 U7500.00 Z100.00 E6000.00 ; Set accelerations (mm/s^2)(this is an i3 style portal printer with a prusa bear like frame with a 220^3 print volume)
On the V-Minion my values are
M566 X900.00 Y900.00 Z60.00 E300.00 ; set maximum instantaneous speed changes (mm/min) M201 X3000.00 Y3000.00 Z200.00 E6000.00 ; set accelerations (mm/s^2)(this is an Ormerod style cartesian cantilever printer with a 180^3 print volume)
Just a note that the accelerations on the V-Minion are quite low compared to the klipper config for it, it is on record with 6 minute speed benchies, but I haven't pushed that far yet.
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@oliof Thanks! It's interesting that your two printers have such a big difference between them! I'm currently using something similar to your first example on my toolchanger with a jerk of 300 and acceleration of 15000, I do get a lot of ringing though so I'll probably be reducing the acceleration somewhat.
Don't want to disrupt this thread, but I wish there was a good way to determine good values for jerk and acceleration with RRF.
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@gloomyandy the first printer isna glorified ender3 with a terrible y motion system that's dragging it down (also 6mm belts). The second is a very compact machine with 9mm belts designed for rigidity and speed.
To be fair, I haven't even started really tuning the V Minion for fast printing simply for lack of time, or the differences would be even more striking.
