Rotating bed with rotating extruder arm (half Scarra half Polar)



  • Hello
    I'd like to see a support from Duet to 3d printer half scarra half polar..
    it is like serial Scara rotating extruder ( one arm ) with rotating polar's rotating bed
    Is it possible? I'm thinking to make this as project, would be nice if duet support that..



  • Duet supports custom transformation matrices. Meaning that you can probably configure it to do that, right now.



  • And/or, reading the description of "polar", that is a rotating bed with one (scara like) arm. That may be what you are describing.

    Take a look here:

    https://duet3d.dozuki.com/Wiki/Gcode#Section_M669_Set_kinematics_type_and_kinematics_parameters


  • administrators

    The difference between your proposed kinematics and standard polar is that in standard polar, the head moves in a straight line along a radius; whereas your proposed kinematics moves the head in an arc, of which one end is I presume at the centre of the turntable.

    A new kinematics class would have to be written so support that. There is guidance on this at https://github.com/dc42/RepRapFirmware/blob/dev/AddingNewKinematics.md. At the heart of it would be the calculation of the arm and turntable position for a given XY position. I think the rest of that class could be very similar to standard Polar kinematics.

    Bear in mind that your proposed kinematics suffers from the same disadvantage that SCARA does (but not as badly), which is that the print head is cantilevered off a rotating joint, making it hard to maintain an accurate height. Whereas with standard Polar kinematics, there is no joint so you can make the radial arm as thick and heavy as you like, and you have the option of supporting it on both sides of the turntable.



  • There is a Danish company making a small printer that works like that. Cute little machine.
    https://sculpto.eu/


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