Homing Extra Axis on XYZ+C printer - S1 Issue



  • Hi everyone,

    First of all, thanks to the Duet team for this wonderfull board full of possibilities 🙂

    I'm working on a 4 Axis particular 3d printer ( XYZCE) with a 0.8.5 DUET ( firmware 1.18.1) and I would like to home the XYZ and C axis.

    I'm doing some test with Pronterface and so far I have :

    Remapped my axis with the following command :
    M584 X0 Y1 Z2 U3 E4

    Set up the endstop with :
    M574 X1 Y1 Z1 U1 E0 S0

    I have checked that my endstop are working fine with the M119 and the board detect all the endstop on and off correctly and I can see them being activated on the board LEDS.

    Everything works fine on the XYZ when I simulate this type of homing macro :

    G91
    G1 X-100 S1
    G92 X0
    G90
    G1 X5

    However when I am doing this same homing routine on my U axis ( which is my C rotary axis ).
    I am able to make a move and to stop when the endstop is activated with G1 U100 S1

    But after this command I am unable to re-use any G1 command without adding S1 or S2 at the end (with the endstop activated or deactivated)
    I mean :
    If I try G1 U10 nothing moves ( either in absolute or in relative mode)
    If I try G1 U10 S1 the axes moves as expected.

    If I restart the board, I am able to use G1 U10 without S1 at the end. This problem appears right after using S1 on the U axis for the first time.

    Also I don't have this Issue on the XYZ axis.

    Did I remapped correctly my axis ? Did I miss Something ?

    Thank you for your help 🙂
    And again, thank you for your work.


  • administrators

    You need to declare the positive and negative limits of the U axis in your M208 S0 and M208 S1 commands respectively. The negative limit will also be the assumed position of the U axis after that G1 U100 S1 command because you have declared the limit switch to be at the low end of the U axis.



  • Oh right,
    the U axis (wich was initially E0), had upper and lower software limit of 0 (checked with "M208" command).
    That was probably causing the trouble.

    Ok I didn't know that the "G1 U100 S1" command (once the endstop is activated) is acting just like the G92 command. Good to know !

    Thank you for your answer 🙂


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