Jerk and Acceleration Settings



  • I posted this in my printer build thread, but it probably belongs here.

    Got a before and after pic at the bottom.

    This print has been pretty challenging, as the design requirements are unusual for PLA.

    It's a fuselage for a 3D printed RC plane, that must be printed in PLA at a high temp (210-250?!) with no fan on, according to the designer. It also must be weighed and come in at a certain weight, with adjustments via the extrusion multiplier. On top of all that it's a thin single and twin wall print.

    I'm at the minimum 210 in the pics.

    If I can get my machine to print this cleanly, I'm pretty much dialed in for anything.

    My e steps are good. I pretty much do an extrusion test for any new roll and write it on the roll for future reference.

    I haven't had the best luck with retraction, just couldn't get rid of the blobs/strings with PLA.

    I went through all the test designs on Thingiverse, and it always cam to the same setting. 0.4mm @ 40mm/sec.

    One of the best things I did was clear all the crap I's added in S3D like Z hop, coasting etc. Just switched the lot off including retraction itself, and then just started at the standard profile and tested retraction in upward increments of 0.2mm.

    When it all got set up the jerk was at X600/Y600/E60, and the acceleration was at X1000/Y1000/E1000.

    This where I'm at now (see below) and prints are much cleaner.

    I'm wondering if I can go even harder there, as the machine sounds really happy and there's no shaking or bad noises.

    I don't want to push it too hard, and I print pretty slow as I prefer quality finish to speed, but if I'm wide of the mark I'd like to dial it in.

    Straight cartesian gantry. The central carriage assy would have to be soomething like 400-600gms.

    Any suggestions?

    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping without interpolation
    M92 X80 Y80 Z800 E119 ; Set steps per mm
    M566 X900 Y900 Z12 E300 ; Set maximum instantaneous speed changes (mm/min)
    M203 X12000 Y12000 Z600 E6000 ; Set maximum speeds (mm/min)
    M201 X1500 Y1500 Z20 E1500 ; Set accelerations (mm/s^2)
    M906 X1000 Y1000 Z800 E600 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout



  • So if you're asking about retraction/blobs/strings then I'd ask what hotend setup you have? Is it direct or bowden, is it geared or not?

    0.4mm retraction is IMO not enough for any setup, for E3D v6 direct I'd use 1mm minimum, and thats for ABS, I'd go to 1.5mm for PLA, faster is better so say 50mm/s, but you can smooth out the retractions by setting modest acceleration on the extruder such as 500. For bowden you're looking at 4mm+ as the amount of retraction that actually reaches the hotend especially with a long tube is way less than that.

    As for the generally, speeding up your machine, a lot depends on how solid a machine it is. For example I run my kossel XL which is an all metal printer at 3000 acceleration, jerk 800-1000, max speeds 15,000 for x,y,z (not that I use these speeds). Extruder depends on the type/model/gearing etc..
    I have gone up to 9000 accleration but the quality of the objects wasn't that amazing. https://www.youtube.com/watch?v=pcJfFgSRtN4

    Try a series of small test parts increasing speeds as you go, just a cube will tell you when your acceleration is too high the corners wont be at 90 degrees, there will be overshoot.



  • @DjDemonD:

    So if you're asking about retraction/blobs/strings then I'd ask what hotend setup you have? Is it direct or bowden, is it geared or not?

    0.4mm retraction is IMO not enough for any setup, for E3D v6 direct I'd use 1mm minimum, and thats for ABS, I'd go to 1.5mm for PLA, faster is better so say 50mm/s, but you can smooth out the retractions by setting modest acceleration on the extruder such as 500. For bowden you're looking at 4mm+ as the amount of retraction that actually reaches the hotend especially with a long tube is way less than that.

    As for the generally, speeding up your machine, a lot depends on how solid a machine it is. For example I run my kossel XL which is an all metal printer at 3000 acceleration, jerk 800-1000, max speeds 15,000 for x,y,z (not that I use these speeds). Extruder depends on the type/model/gearing etc..
    I have gone up to 9000 accleration but the quality of the objects wasn't that amazing. https://www.youtube.com/watch?v=pcJfFgSRtN4

    Try a series of small test parts increasing speeds as you go, just a cube will tell you when your acceleration is too high the corners wont be at 90 degrees, there will be overshoot.

    Sorry, it's a direct drive extruder. The standard setup that comes on a Zortrax.

    I'll just put it back to the standard 1mm/30mm sec setting that's default for the S3D PLA profile.

    Just watched a Tom's guide video, and he mentioned 20-30% of printing speed as a good starting point for jerk, so I was right on at 900 for XY and I'll try 800 for E.

    So…

    M566 X900 Y900 Z12 E800 ; Set maximum instantaneous speed changes (mm/min)

    Acceleration, he mentioned 9000, but you've mentioned that being harsh and it's a lot higher than I'm running right now, so how about:

    M201 X3000 Y3000 Z20 E500 ; Set accelerations (mm/s^2)

    And max speeds he mentioned really didn't come into play so much, and to just enter a figure "and be done with it", so...

    M203 X12000 Y12000 Z1200 E8000 ; Set maximum speeds (mm/min)

    My chassis is the Zortrax solid welded cabinet, nothing moves but I still don't want to flog everything out.

    How do these figures sound?

    I should point out that I'm not really interested in "speed printing", just getting good clean quality prints. Of course I don't want it dragging its feet, but I don't want to wear parts out prematurely as well.



  • They look fine, see how it runs, its good to push it just for a test, to see how far it can go, then you know how much headroom you have when running at much more more sensible settings.



  • I kind of put my thoughts in the other thread that Corexy posted but regarding accelerations, try something like diagonal infill on a 100mm x 100mm cube (or 50X50 - doesn't really matter) and just observe how it looks as the moves get shorter and shorter. I'd think that at 9,000 it'll try and shake itself to bits or at least look pretty alarming. If it does, reduce it down until the speed "looks right". I've found that 1200 acceleration works well for my CoreXY (but it has a seriously heavy hot end).



  • @deckingman:

    I kind of put my thoughts in the other thread that Corexy posted but regarding accelerations, try something like diagonal infill on a 100mm x 100mm cube (or 50X50 - doesn't really matter) and just observe how it looks as the moves get shorter and shorter. I'd think that at 9,000 it'll try and shake itself to bits or at least look pretty alarming. If it does, reduce it down until the speed "looks right". I've found that 1200 acceleration works well for my CoreXY (but it has a seriously heavy hot end).

    It's hard this…you get such wildly different answers.

    I'll play it safer:

    M566 X900 Y900 Z12 E800 ; Set maximum instantaneous speed changes (mm/min)
    M203 X12000 Y12000 Z1200 E8000 ; Set maximum speeds (mm/min)
    M201 X2000 Y2000 Z20 E500 ; Set accelerations (mm/s^2)

    I've never had any problem with the stepper motors like skipping or any thing, they seem strong. I know the standard Zortrax extruder setting was 400mA, but they had trouble with it and some people including myself wound it up to 600mA. Over 600 it started to show wavy patterns in the prints.

    There's also one speed I can't get to change, the Z axis when it homes at the start of a print. I can get it to move faster when I move it manually, but the homing speed is always the same, and it's too slow and makes an annoying resonating noise.

    I just want to step it up 50%. Can anyone tell me where I find that?



  • You will get wildly different answers because the speed and accel settings will be wildly different depending on machine kinematics and to a large extent users personal preferences. Personally, I find the best approach is simply trial and error.

    Ref homing speed, it's the F parameter in M558 where you define the probe type. https://duet3d.com/wiki/G-code#M558:_Set_Z_probe_type.

    HTH

    Ian



  • @deckingman:

    You will get wildly different answers because the speed and accel settings will be wildly different depending on machine kinematics and to a large extent users personal preferences. Personally, I find the best approach is simply trial and error.

    Ref homing speed, it's the F parameter in M558 where you define the probe type. https://duet3d.com/wiki/G-code#M558:_Set_Z_probe_type.

    HTH

    Ian

    Yes that helped immensely thank you.

    So good not to hear that horrible resonating noise at the start of each print.

    Cheers,



  • And….......it turns out it was just a crap roll of filament.

    Changed my expensive roll of Verbatim for a roll of cheap Aussie generic, and knocked out a near flawless print.

    Now running a roll of Colorfabb and that's beautiful too (but need very different start and print temps than the others).

    One thing I'm learning after years of only using ABS is that different brands, and even rolls of PLA vary much more in settings requirements and print quality.

    So it's worth trying out different filaments, cheap can be good and expensive can be crap.



  • Interesting your observations about Verbatim filament. I ordered some "common or garden" PLA but the supplier was out of stock of the particular colour I wanted so they sent me the more expensive Verbatim instead at no extra cost (big deal). Long story short - I'd rather have had the cheap "crap" and won't be using Verbatim again.



  • @deckingman:

    Interesting your observations about Verbatim filament. I ordered some "common or garden" PLA but the supplier was out of stock of the particular colour I wanted so they sent me the more expensive Verbatim instead at no extra cost (big deal). Long story short - I'd rather have had the cheap "crap" and won't be using Verbatim again.

    I have had no luck at all with Verbatim in PLA or ABS.

    I also won't be using it again.



  • I am running a Bowden direct drive extruder and my results might surprise some people but I can attest these settings work very very well.

    I do not have a part cooling blower and have successfully completed several benches like this one with PLA: https://www.thingiverse.com/thing:1619976 and 3dbenchy…. I do not have any stringing, oozing or blobbing like when I started.

    Warning, I need to tame some of these back as some of them cause my printer to bang around depending on what is being printed but the prints come out amazing 🙂

    M566 X9000 Y9000 Z12 E9000 ; Set maximum instantaneous speed changes (mm/min)
    M203 X12000 Y12000 Z375 E12000 ; Set maximum speeds (mm/min)
    M201 X9000 Y9000 Z150 E6000 ; Set accelerations (mm/s^2)
    M906 X850 Y950 Z950 E950 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M572 D0 S0.1
    
    

    My Slicer is simplify3D and the bridging in it sucks, most overhangs in these models never get bridge mode enabled but I was still able to get amazing results none the less.

    Slicer settings:

    62mm/s print speed
    115mm/s retraction speed
    1.85mm retraction
    0z hop
    Outline direction: Outside in
    Outline overlap: 10% (too much overlap on a well tuned printer will cause bulging like you see I found 10% to be ideal for well tuned estep and filament temp)
    Only retract when crossing open spaces is unchecked
    force retraction between layers is checked
    perform retraction during wipe movement is checked
    
    

    My kids ran off with my benches but the results with snappy XY and snappy extruder completely eliminated any stringing and successfully connected non bridge parameter outlines (S3D bug, they should be treated as bridges) and it did so without the assistance of cooling and a 205c temp on PLA.

    Now I just need to find the best jerk settings so my printer does not sound like its banging with every movement of the axis…. I am finding fast moves are the best way, it makes for ultra sooth quality prints with no defects but I need to find the sweet spot for jerk settings to make it maintain the quality that the high speed is giving



  • P.S. I have a sheetmetal frame Davinci Pro so your results could vary depending on frame and motors but this thing seems to respond well to speed.


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