Three Rotary Axes Homing

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  • November 19, 2019 at 1:13 am #11675
    BentCookie
    Member

    Hello all,

    I’m evaluating my controller options for a CNC Gimbal, the most promising option I can see so far is the tinyG. There are no cutting forces involved, only inertial forces. This machine would consist of 3 rotary axes A,B, and C. With the final stepper driver reserved for a potential future linear axis.

    I require homing on all three of these rotary axes. I have looked through the forums and wiki documentation, and everything I can read indicates that homing is not available on axes B and C.

    Is it true that homing is only supported on X/Y/Z/A axes?
    Could someone please recommend a workaround or alternative controller if this is the case?

    Cheers

    November 19, 2019 at 1:27 am #11676
    Zootalaws
    Member

    All axes can be homed.

    The docs use ‘x’ as the example, but xyz and abc are supported.

    https://github.com/synthetos/TinyG/wiki/Homing-and-Limits-Description-and-Operation#g282—homing-sequence-homing-cycle

    November 19, 2019 at 1:34 am #11677
    BentCookie
    Member

    Hey Zootalaws,

    Thanks, I’m still hesitant because that very page states “Substitute any of XYZA for the ‘x’ in the table.” With regards to homing configuration.

    The switch configuration table also only lists XYZA and not B or C.

    This is in agreement with the Configuring tinyG summary.

    November 19, 2019 at 4:30 am #11678
    Zootalaws
    Member

    Whatever.

    November 19, 2019 at 6:24 am #11679
    cmcgrath5035
    Moderator

    BentCookie

    Interesting question, the Wiki reference posted by Zootalaws does reference, in logic space, homing actions for all 6 available axis assignments for a four motor tinyG, I believe it is also a correct statement that the X,Y,Z and A axis Min/Max switch ports are assigned in the base code to those specific axis functions and not reassignable. Thus there are no connections available to feed the homing logic when homing a B or C axis.

    I am not a developer, but a quick look at https://github.com/synthetos/TinyG/blob/master/firmware/tinyg/switch.h indicates to me that tinyG FW as built for the tinyG hardware only builds support for 4 Min and 4 Max switches, X,Y,Z and A.

    It is likely that rework of various header files and recompiling tinyG could attach the physical I/O ports to B and C axis homing logic.
    How to get there is beyond my pay grade, so I have asked a developer to have a look here and comment.

    November 19, 2019 at 8:19 pm #11680
    BentCookie
    Member

    Hey cmcgrath5035,

    Thanks for that link, it does indeed look like tinyG only supports XYZA homing unfortunately. I wonder how much would need to be changed to support any axis homing and why it isn’t that way currently.

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