linear advance

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    Can you please run M205 and show the output?


    Send: M205
    Recv: ok

    looking through the firmwareI see that this is setup


    //#define CLASSIC_JERK


    #define DEFAULT_EJERK 5.0 // May be used by Linear Advance



    Please also take a screenshot of your repetier Host menu

    I’m using octoprint. According to this post https://forum.repetier.com/discussion/4951/how-to-open-eeprom-settings-does-it-allows-export-and-import-in-xml-files


    Mac has eeprom for repetier-firmware only

    unfortunately I’m on a mac and running command+E brings up a blank screen.


    Also I notice your Lin advance K factor is .22??!

    The firmware is set to the default K factor but the s3d start script is


    G28 ; home all axes

    ; Add Extruder 0 no mixing
    M163 S0 P1
    M163 S1 P0
    M164 S0

    ; Add Extruder 1 no mixing
    M163 S0 P0
    M163 S1 P1
    M164 S1
    M900 K1.1 ; set k factor PLA

    which brings up another question the start script only changes the K factor for E0 and E1 remains at the default. I have to update E1 from the lcd menu. What do I have to add to the start script to set the K factor for both extruders? Do I add M900 K1.1 ; set k factor PLA to both entries?


    I’m not 100% sure that’s the case, I’ll test today if I get a chance. The obvious answer would be to add M900 Kxx to the tool change script in s3d.

    That won’t affect the e jerk and acceleration though which are both integral to linkers advance working. I’ll provide more clarification later today when I get to work.



    OK, that log doesnt have any debugging. Can you please check your configuration_adv file for the following and make sure it is uncommented :

    #define LA_DEBUG

    Then can you start a MM print and senda copy of the log. It should show any errors with Linear advance in the log file which will make diagnosis easier.


    #define LA_DEBUG is enabled and a snippet of the terminal output is attached


    Ok. So acceleration limited is an indication that linear advance is doing its thing. I do notice that you linear advance commands occur before the tool change, which would only be an issue after the first tool change. Simplify has a command to denote “after tool change” https://forum.simplify3d.com/viewtopic.php?t=7552 which will make the M900 command occur after the tool has changed.

    None of that should affect your print stringing as the commands should really only need to be run once per extruder (if that).

    So I the absence of errors, I’m wondering if the Lin advance is struggling to deal with the large retraction required by the tool change?

    While printing with your purge block, can you identify when the stringing occurs? Does it occur while the hotend is moving only to the purge block or does it occur while moving only from the purge block? Or both to and from? Does it occur in one material only? Or both material colours?

    So we need to do more digging. Can you try a single material print with hotend 1 and a simulated purge block ie. solid cube to be printed with the same material as hotend 1. Then repeat this print with hotend 2 and simulated purge block also with hotend 2? Same result on both hotends? If differing results – tweak temperature settings with the stringier of the two until similar results. Is there a temperature difference to achieve the same results?



    can you identify when the stringing occurs?

    Going from the purge block to the print only

    firing off a print right now


    there is stringing going from the print to the purge block and from the purge block to the print


    k1.1, 3.25 retract, 190c


    All those cubes look over extruded. . Have a look at the corners. Can you reprint with higher X Y Jerk settings to see if corners come out square? Also did you calibrate your extruder? Have you measured the actual filament width? Is that reflected in your slicer?

    Maybe worth adjusting K factor and Temperature during print? Im running out of ideas that don’t involve plenty of practice and methodical testing.



    Also did you calibrate your extruder?

    Yes, 100mm command, 100mm extruded. I’m not sure of the best way to calculate the extrusion multiplier. I tried printing a 2 layer side wall cube and measured the thickness of the wall and adjusted the multiplier based on that but the prints looked under extruded. Then I printed a rectangle 60x100x.75mm and picked the flattest, smoothest print produced at the multiplier used. Clearly the above prints are over extruded. I reduced the multiplier by 3%, to 101% for this print. This was printed with a K factor of .5-1.4 changing every 10% or 10 layers, 190c.


    Can you reprint with higher X Y Jerk settings

    What command do I use to find out what the current jerk settings are?


    This was printed with a k factor of .5-1.4 changing every 10 layers, 190c, extrusion mult of 101%

    stringing on the part is coming from the purge block
    stringing on the purge block is coming from the part


    According to


    M503 to display

    And M205 to set.

    Looks like one setting for both extruders.

    Have you measured your filament width? Take an average over 1meter


    Send: M503

    Recv: echo: G21 ; Units in mm (mm)

    Recv: echo: M149 C ; Units in Celsius


    Recv: echo:; Filament settings: Disabled

    Recv: echo: M200 D1.75

    Recv: echo: M200 T1 D1.75

    Recv: echo: M200 D0

    Recv: echo:; Steps per unit:

    Recv: echo: M92 X80.13 Y80.12 Z3195.42 E415.00

    Recv: echo:; Maximum feedrates (units/s):

    Recv: echo: M203 X200.00 Y200.00 Z10.00 E50.00

    Recv: echo:; Maximum Acceleration (units/s2):

    Recv: echo: M201 X1000.00 Y1000.00 Z100.00 E500.00

    Recv: echo:; Acceleration (units/s2): P R T

    Recv: echo: M204 P1000.00 R500.00 T1000.00

    Recv: echo:; Advanced: B S T J

    Recv: echo: M205 B20000.00 S0.00 T0.00 J0.01 <<==is this jerk settings here?

    Recv: echo:; Home offset:

    Recv: echo: M206 X0.00 Y0.00 Z0.00

    Recv: echo:; Unified Bed Leveling:

    Recv: echo: M420 S1 Z10.00


    Recv: Unified Bed Leveling System v1.01 active


    Recv: echo:; Active Mesh Slot: 1

    Recv: echo:; EEPROM can hold 7 meshes.


    Recv: echo:; Material heatup parameters:

    Recv: echo: M145 S0 H190 B60 F0

    Recv: echo: M145 S1 H240 B110 F0

    Recv: echo:; PID settings:

    Recv: echo: M301 P18.03 I0.97 D83.46

    Recv: echo: M304 P148.98 I29.30 D504.98

    Recv: echo:; Z-Probe Offset (mm):

    Recv: echo: M851 X-25.40 Y-6.50 Z-0.20

    Recv: echo:; Linear Advance:

    Recv: echo: M900 T0 K1.40

    Recv: M900 T1 K1.10

    Recv: echo:; Filament load/unload lengths:

    Recv: echo: M603 T0 L0.00 U100.00

    Recv: echo: M603 T1 L0.00 U100.00

    Recv: echo:; Tool-changing:

    Recv: echo: Z2.00

    Recv: echo:; Filament runout sensor:

    Recv: echo: M412 S1

    Recv: ok


    Junction deviation is different and newer than Jerk – AFIK it accomplishes a similar thing

    That line you highlighted isnt echoing X and Y Jerk for some reason – perhaps a firmware bug?

    According to Marlin Docs

    M205 X10 Y10

    will set Jerk for X and Y to 10

    M205 E5

    will set jerk for E to 5


    This line is set in the firmware


    #define DEFAULT_EJERK 5.0 // May be used by Linear Advance

    Its the XY jerk and possibly junction deviation which causes the over extrusion on corners. E Jerk settings specifically affect retract extrusion movements where the extruder moves from a forward to a reverse direction.

    You havent actually measured measured the filament?

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