Jerk/accel settings not working for me

deckingman

1. Before you do that, could you try an earlier version of firmware - prior to 1.20 (say 1.19). The reason I suggest it is that there are similarities in the behaviour that you are seeing and something I saw back in January. It's in this very long thread which is mostly related to pressure advance behaviour with multiple extruders (mixing hot end). https://www.duet3d.com/forum/thread.php?id=1999&p=3. Unfortunately I went off on my travels and since then I haven't had chance to do much printing this year. I'm still on 1.20 RC "something" so things may have changed again. At that time, David had recently changed something in the firmware that I think was to do with pressure advance behaviour but the result was that I was getting jerky behaviour on arcs. My memory is a bit hazy but IIRC it seemed that the firmware had become more sensitive to gcode which produced varying segment sizes for arcs.

2, If you do go back to Rambo / Marlin, please report back if it fixes your problem. I'm sure David will "pull out all the stops" to implement a fix if it can be shown that another board/firmware does something better than Duet.

dc42

@Ret, please share the gcode that Cura generated, so that I can see whether it has the same issue as the S3D gcode.

Phaedrux

I sliced the model STL sample that was posted earlier in Slic3r PE and the extruder moves were to 5 decimal places. Without the full model it's hard to know what the orientation it is printed in, but to test it I rotated it so that the flat part of the circle is to the bed. I did a test print of the first few mm.

The part is very thin, and I suspect that S3D is trying to lay a line thinner than the nozzle diameter and is breaking it up into small sections of extruding and not extruding.

You can force Slic3r to do similar behavior by turning off detect thin walls, which merges the inner walls into a single gap fill move. Slic3r seems to handle it a lot better.

That's just a thought though.

Here is what Slic3r generated

https://www.dropbox.com/s/pigl8mxi9h50fnu/TL_CUT.gcode?dl=0

deckingman

@Phaedrux,

Are the segments lengths for each curve all more of less the same size? I've had issues with Slic3R (PE) where they are not. This seems to cause havoc with printing curves, especially if pressure advance is employed.

dc42

The main problem with the file that @deckingman refers to news that the ratio of extrusion amount to XY movement amount was varying wildly, especially for the very short segments.

Another issue that causes jerky movements is when S3D inserts tiny G0 moves (no extrusion) in between extruding moves. It seems to do this always when generating curves in the skirt, but so far I haven't seen it do it in the main part of the print.

Ret

Deckingman,
I will give an earlier version a shot within the next day or so, thank you!

dc42,
https://drive.google.com/file/d/1bpdNy6O7MxUwSIXr4ZoWXPekSAoUQRRx/view?usp=sharing
This isn’t an exact copy of the other model used in the gcode link I sent with s3d. It is the same part but started at a different position. I still am unclear what you mean by little segments, but to me, visually, the outer layers look similar, maybe slightly cleaner with Cura.

Phaedrux,
Those varying internal extrusion widths are how I set it up. The problem occurs on all parts of the print(outer layers, inner layers, and infill). The outer and inner layers are consistent, but the infill segments vary to fill the space since it’s a unique geometry.
–---------
I have attempted printing with pressure advance (0.01-0.3), with no real notable change in quality. I did however have to modify jerk settings as I went higher with the pressure advance, but I believe that’s as to be expected.

Ret

I went back to 1.19, no real significant changes between the item printed (same gcode) on 1.21. 1.19 seemed to stutter more, at least it looked like it. There’s nothing smooth about the movements as opposed to my previous marlin.

DC42, have you ever looked into the acceleration and jerk code in marlin? You also did mention the extrusion value needed to be 5 decimal, instead of 4. Is that just a preference or does it actually NEED to be 5 for your firmware? Of course 5 will be quite a bit more accurate, but it seemed to work just great with the other firmware I was running. Cura using 5 has no noticeable impact as opposed to S3D’s 4 in my experiments with the duet.

dc42

This is on my list to look at. I strongly suspect that Marlin doesn't do extruder jerk planning at all.

Shen

I don't know if this is related, but I sliced a model using S3D that runs very badly on my printer. However, the printer runs fine if I comment out every other line in the gcode during cornering.
My custom printer running 2.0 alpha 1 printer makes loud noise at corners.
https://youtu.be/ZIlCNwHtu50

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Phaedrux

@deckingman I think I have seen this recently when printing some PETG with a higher pressure advance value. Jerky motion on curves leading to vertical banding where the extruder pauses/slows down very briefly on the curve.

Ret

Please do let me know what you find out, @dc42, after looking at marlin.

@Shen, I haven’t manually modified g-code to alleviate any issues yet, but that’s an interesting find. It seems like this firmware especially dislikes how S3D handles things. Marlin didn’t have any jerky issues for me pre-duetWifi upgrade.

For now though, I’m left with no choice but to go back to my old board running marlin until some improvements come out. It’s been tough completing orders with one printer down. However, on weekends I’d have no problem going back to the duet to try any suggestions anyone might have.

Thanks guys!

Shen

@Ret, For me there are workarounds to the problem. Such as slowing down perimeters, lower jerk/acceleration, but I don't know if you are willing to sacrifice the speed. I had to slow down to 2mm/s jerk and 1500mm/s^2 acceleration for the noise to go away, but before I switch to the internal drivers, with the filter function of my external driver I was able to achieve 10mm/s + jerk and 3000mm/s^2 + acceleration without any issue.

Ret

@shen I did find slowing things down a lot helped significantly, but it just throws me off that Marlin was able to do it so successfully without any signs of funny jerky motions. I've had to cut my speed in half to get okay results, but even then, they're not as good as prior. I can't afford to lose half the speed I normally print at. I am however glad to hear that I'm not the only one who is having this problem. Thank you for your reply!

dc42

I hope to find time to try this print today.

dc42

@ret said in Jerk/accel settings not working for me:

Sorry for taking a bit to reply, I had to put my old board on for a bit to finish a project. 60 does seem low after looking at everyone else's, but it worked PERFECT on marlin which really throws me off that this firmware is so different when it comes to the jerk and accel. I have attempted it with 2 slicers, S3D and Idea maker, both same jerky motion, nothing is smooth. Here is my gcode though, feel free to check it out!

https://drive.google.com/file/d/1dwXWh0slnOdZQeG-oGh5iy_89H0ujWp4/view?usp=sharing

I just tried printing that file from SD card on my Cartesian printer. It prints smoothly for me, except when it does tiny "stitching" movements to do the infill between the two circular perimeters. I had to increase the extrusion factor to 250%, so I think you are probably using 3mm filament (I am using 1.75mm).

I have been assuming that you are printing the file from SD card. If instead you are printing over USB then there are some flow control settings in your host program that should be changed.

deckingman

@phaedrux said in Jerk/accel settings not working for me:

@deckingman I think I have seen this recently when printing some PETG with a higher pressure advance value. Jerky motion on curves leading to vertical banding where the extruder pauses/slows down very briefly on the curve.

TBH, I've given up trying to use pressure advance. For whatever reason, my Diamond hot end needs high values and whilst pressure advance works really well for straight lines, I've never been able to get smooth curves. Initially it seemed it was just when using multiple extruders (mixing hot end) but later firmware seems to give me problems even when using a single extruder.

dc42

@deckingman said in Jerk/accel settings not working for me:

@phaedrux said in Jerk/accel settings not working for me:

@deckingman I think I have seen this recently when printing some PETG with a higher pressure advance value. Jerky motion on curves leading to vertical banding where the extruder pauses/slows down very briefly on the curve.

TBH, I've given up trying to use pressure advance. For whatever reason, my Diamond hot end needs high values and whilst pressure advance works really well for straight lines, I've never been able to get smooth curves. Initially it seemed it was just when using multiple extruders (mixing hot end) but later firmware seems to give me problems even when using a single extruder.

Hi Ian,

After I am back from Sweden next week, please provide an example single-extrusion GCode file and config.g settings for me to run on my bench system.

deckingman

@dc42 said in Jerk/accel settings not working for me:

@deckingman said in Jerk/accel settings not working for me:

@phaedrux said in Jerk/accel settings not working for me:

@deckingman I think I have seen this recently when printing some PETG with a higher pressure advance value. Jerky motion on curves leading to vertical banding where the extruder pauses/slows down very briefly on the curve.

TBH, I've given up trying to use pressure advance. For whatever reason, my Diamond hot end needs high values and whilst pressure advance works really well for straight lines, I've never been able to get smooth curves. Initially it seemed it was just when using multiple extruders (mixing hot end) but later firmware seems to give me problems even when using a single extruder.

Hi Ian,

After I am back from Sweden next week, please provide an example single-extrusion GCode file and config.g settings for me to run on my bench system.

Hi David,

Yes I can do that but at the end of this very long thread https://forum.duet3d.com/topic/1935/more-strange-pressure-advance-behaviour/60, on 21st Jan you said this

"Ian, I have just tried slicing my test circles using Cura 3.1 instead of S3D and the extrusion speed consistency is much better, about 1% instead of 8.4%. So until I change the pressure advance code to better handle changes in extrusion rate that shouldn't be there, you might like to try slicing your models with Cura instead of S3D. I think that will fix most of the problem."

However, Cura and S3D aren't viable options for me because they aren't good for multi (more than 2) coloured objects. I guess I could use one or other but then I'm reduced to using 1 or maybe 2 colours and that's not what my printer is designed for. So, no offence intended, but it's just easier for me to stick with Slic3R and just not use pressure advance.

dc42

I've added a page on known causes of jerky printing on the Troubleshooting section of the wiki, at https://duet3d.dozuki.com/Wiki/Jerky_movement_when_printing.

Maglin

@Ret as already said. You should change your micro stepping to 1/32 at the max. No FFF printer will have any better results going higher. Also, change your steps/mm. If you are using pressure advance turn it off. You really need a good tune on your extruder before you ever mess with pressure advance.

Your accelerations for movement on axis is high but very low for your extruder. I have a different printer but you might want to try my settings.

M566 X750 Y750 Z90 E1200 ; Set maximum instantaneous speed changes (mm/min)
M203 X18000 Y18000 Z6000 E9000 ; Set maximum speeds (mm/min)
M201 X1800 Y1800 Z250 E10000 ; Set accelerations (mm/s^2)

With a "Jerk" of 1mm/s on your extruder, you are going to have crazy strange stuff happening especially if you are using pressure advance. I would expect massive pauses on small circle/arcs. I actually complained about PA a while back but it was all in my tuning. I was having what you are but not to your extent.

You might not want to use my Z settings as I know for a fact you have a completely different setup for your z than I do. You might not try this but honestly, it's probably the few things jamming you up.

Also, I used to use S3D exclusively. Now I only use Cura 3.2.1+. But that requires a lot more tuning and tweaking of settings. S3D makes a lot of garbage code but it's easy to use and gives very good top layers. Make these changes and if your problems go away then you can start doing more tuning. Maybe give Cura a try. It's given me much better control over my prints and produced astonishing print quality. Best of luck.