Polar Coordinate based CNC

What all would have to happen to allow a CNC machine to be based on a polar coordinate system rather than a rectangular one. The big benefit to me would be that the single most expensive component of a router/plama type of system is the slides and drive components (the screws or rack/pinon not the motor itself) for the longest axis (for systems of the size/type I have in mind this would be to move a gantry). But I assume that would mandate a change to the controller so it could interpret g-codes as polar coordinates. Are there any controller packages out there currently that support polar-coordinates?

Thanks,

Lee Wenger
Denver, CO

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