Micro stepping on a per-axis basis ?

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  • May 6, 2012 at 8:58 am #1874
    lpdc
    Member

    Hello,
    From what I could gather on the wiki, micro stepping setting is achieved by unsoldering/resoldering cms resistors to select between full step, half, quarter or eights steps. Correct me if I am wrong but it seems that such setting is global for all 3 axis.
    I would like to set the microstepping values differently for the Z axis than for the other 2 axis.
    Do you think there might be a reasonable way to do this ? Could I get away with cutting some traces on the board or would that mess things up with grbl itself ?
    I would like to keep X and Y axis with 8th microsteps while setting the Z axis to full steps.

    Any insights welcome.

    Fabrice

    May 7, 2012 at 12:19 pm #1875
    alden
    Member

    I’m not sure how easy this is. I can direct you to the schematics for the v2 grblshield here:
    https://github.com/synthetos/grblShield/tree/master/hardware

    It would involve cutting and jumping a bit., Are you interesting in a different Z than X and Y? You could leave X and Y alone (or change the jumpers), and disconnect Z and wire it in separately.

    May 7, 2012 at 1:38 pm #1876
    lpdc
    Member

    Thank you Alden.
    I downloaded the schematics. I guess I’ll see when I have the board in my hands how feasible this looks. I will probably need to cut the traces for Z and wire both pins to the ground through a resistor.

    Fabrice

    May 8, 2012 at 5:58 am #1877
    alden
    Member

    If you wanted to set the Z axis to no 1x microstepping you can simply ground the Z axis USM0 and USM1. The resistors are on the board for convenience of changing the microsteps, and could be zero ohm resistors. The USM lines can be tied to hi or lo directly without the need for a resistor.

    I would also look at the documentation on the the TI DRV8811 driver chip you can find here:
    https://github.com/synthetos/grblShield/tree/master/references

    Refer to page 11.

    May 11, 2012 at 4:53 am #1878
    lpdc
    Member

    Thank you Alden.
    In the end I chose to use TinyG instead of Grblshield as the former allows me to do this directly through software.
    I thought I would add this comment for reference if someone is looking at this thread.

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