Mapping A-axis as linear

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  • May 26, 2015 at 5:25 pm #7749
    berlinguyinca
    Member

    dear all,

    I’m in the need of a tinyg configurations supporting 4 linear axes. Is this possible or can it be simulated?

    Basically I want to:

    X – move left to right
    Y – move for and back
    Z – move up and down
    A – move a second Z axis up and down independent of the first Z axis

    I need a movement of ~10 cm for the A axis

    thanks!

    May 26, 2015 at 8:16 pm #7753
    cmcgrath5035
    Moderator

    Assuming you know how to create Gcode for Axis motion, you need to convert the parameters that an A axis understands into linear motion , then place these translated parameters into the appropriate A axis fields. For example, if your A axis mechanics require 2 revolutions of the motor to make 10cm of linear motion, then you need to enter an A axis directive to rotate the motor twice.

    May 29, 2015 at 1:31 pm #7764
    berlinguyinca
    Member

    thank you, could you provide me with an example by any chance? I’m a bit new to rotational axis and only worked with linear modes so far and somehow have a hard time finding this info, since every tutorial kinda assumes that you know what you doing and I have not really an engineering background.

    May 29, 2015 at 2:22 pm #7765
    cmcgrath5035
    Moderator

    I have never tried it either.
    Give this CP item a look and watch:

    May 29, 2015 at 2:38 pm #7766
    cmcgrath5035
    Moderator

    Lets say your second Z axis, I’ll call it ZA axis, has its stepper directly connected to a 2mm pitch lead screw. To move 10mm, you would need 5 revolutions.
    So, a G1 A1800 (5×360 degrees=1800) Gcode command would move your ZA axis 10mm. You have to experimentally determine if you want a G1 A1800 or G1 A-1800 to move in the direction you want

    I am not aware of any Gcode generator that would generate this for you, you will have to hand code.

    May 29, 2015 at 3:38 pm #7767
    berlinguyinca
    Member

    thanks this should get me started and I highly appreciate the feedback. Writing the GCODE is no problem, now that I have an idea what todo.

    May 29, 2015 at 4:37 pm #7768
    berlinguyinca
    Member

    ok worked without issues. I also had an config error in my tinyg, which set the max travel rate for a to -1

    May 29, 2015 at 4:54 pm #7769
    cmcgrath5035
    Moderator

    -1 is the default for unused axes, essentially shuts them off.

    Good luck!

    May 30, 2015 at 10:53 am #7772
    alden
    Member

    Glad you worked that out. The other way to do this is to set the rotary axis (A, B, or C) in Radius mode, then set a radius value for the axis. This interprets linear input as if it were wrapped around a disk. This is explained on the wiki on the configuration page under Radius mode. You have to work the math a bit, but it does work.

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