Modification for rotational axis

Dear Reprap community,

My name is Mathijs and I'm a Design Engineering student from The Netherlands. For my graduation project I'm developing a concept for customizable shoes through digital fabrication. I'm a reprap newbie... so please be kind.

As my final project I have chosen to print shoes with a modified Reprap (Prusa Mendel v2 which I just finished building). I want to replace the normal Y-axis with a rotational axis centered under the x/y assembly on which a last shape (shoe/foot shape) is mounted. The physical modifications for this axis is not really a problem. But getting the software side to work is a bigger challenge.

I can take a few different approaches:

I. Translating a 3D model of the last into a height map on which I can then project the pattern I'd want to print. Sort of "unfolding" the shape of the
shoes in relation to the angle of the axis.
II. Modifying the egg-bot software to include a Z-axis because the current eggbot system relies on a spring/gravity
III. Figure out how a CNC-lathe works and try to modify such a system (but this is actually also a 2-axis machine)

I've added a rendering of the setup I'm thinking of now and some pictures of hand-made models of what the shoes should look like in the end

Any tips/advice is welcome because I really don't know where to start...

Kind regards,
Mathijs

From the machine controller side there's nothing special about a rotational axis. A translational distance can also be seen as a rotational distance. If you send something like G1 Y20 F100 this just means "do a number of steps on the Y motor at the given speed". How many steps is expressed in the STEPS_PER_M or STEPS_PER_MM configuration variable. Adjust the latter to a value convenient for you.

Good luck with writing a slicer which slices into cylinders instead of planes. Can undoubtly be done, but likely it's more than a weekend's task.

Likely you want a much higher resolution on your rotational axis than what the sketch in the first picture shows. I'd increase the size of the pulley on the axis a lot, like 10, better 100 times the size of the pulley on the motor.

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