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Jerk / Motion control


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Posted · Jerk / Motion control

Hi,

 

In Cura 3.6 I switched off Jerk control via the tick box. I would have assumed that this should then let the printer use its defaults.

 

Though something strange happened, after printing, I did an M503 and it returned a jerk of 20. I double checked my FW and it was set to 8 when I flashed it.

 

I rebooted my printer and a M503 then reported the 8 I was expecting.

 

Any suggestions what I should do to test what is causing this please? Any ideeas what I can look for in the GCODE to check if something is changing it?

 

Ultimately, what I want is to be able to control the print speed itself in Cura, but accelleration and jerk should be done by the printer firmware defaults.

 

FYI. Printer is a CR-10S running Marlin 1.1.8.

 

Thanks

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    Posted · Jerk / Motion control
    1 hour ago, DivideByZero said:

    Any suggestions what I should do to test what is causing this please? Any ideeas what I can look for in the GCODE to check if something is changing it?

     

    Be aware that Marlin uses "sticky" parameters. All settings stay at the last value until the next reboot (or M501).

    If you want to be sure that every print starts with the stored values, add M501 at the beginning of the start script.

     

    If you want to check the generated gcode: jerk can be changed with M205, acceleration with M204.

    (follow the links for details).

     

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    Posted · Jerk / Motion control
    58 minutes ago, fergazz said:

    Did you save it in EEPROM? 

     

    Yeah, when I updated the FW I saved it. Something had changed the max_x_jerk etc. from 12 to 20 (just double checked). Reboot and it was back to normal.

     

    21 minutes ago, tinkergnome said:

     

    Be aware that Marlin uses "sticky" parameters. All settings stay at the last value until the next reboot (or M501).

    If you want to be sure that every print starts with the stored values, add M501 at the beginning of the start script.

     

    If you want to check the generated gcode: jerk can be changed with M205, acceleration with M204.

    (follow the links for details).

     

     

    Thanks - good info.

    Definitely happening in Cura. I even have M204 + M205 setup in my startup code for the correct values... but then after that, I get this:

     

    ;LAYER_COUNT:50
    ;LAYER:0
    M107
    M204 S5000
    M205 X30 Y30
    G0 F3600 X130.766 Y130.38 Z0.2
    M204 S500
    M205 X20 Y20
    ;TYPE:SKIRT

     

    Above we can see  X20 Y20 - which is what it ends up.

     

    Just to double check... I don't have "Enable Acceleration Control" or "Enable Jerk Control" on, that's all I need to switch off right?

     

    Let me reset my profile again and see if I still get that. At least I can find out without having to print now. Thanks

     

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