Here is a new polar configuration that we just got working as a proof of concept. It has two platters, one rotating on top of the other, but with stationary motors that result in a dead simple drive system. Video here: [www.youtube.com]

Printing: Motion is smooth and the platters can move surprising fast. Little or no frame vibration/shaking since the start/stop motion is rotational.

CNC MIlling: A lot of this design was driven by the desire to eliminate x-y plane linear bearings, belts, and pulleys to avoid problems with metal dust from the mill. The two platters are supported by aluminium "Lazy Susan" bearings which are strong, are cheap at $8 apiece, and readily available. The tools heads are stationary which keeps things simple and sturdy.

Scanning/Machine Vision: A fundamental advantage to polar designs is their ability to scan objects, and this one allows that with rotational, as well as vertical and lateral motions which should help refine images (to be verified).

Cost: Total cost is expected to be quite low, although that has not been tallied yet through a B.O.M.

Right now a fairly crude python script transforms the GCode before being sent to the Arduino via Repetier. It translates position fine, but is not so great with velocity and definitely not with acceleration. A much better solution would be to do all of this through firmware. Any pointers to such projects would be appreciated.

Very nice concept, I have always felt that rotation is more efficient, but adds other complications, but as
processing power has increased these complications are not the barrier they once were.
This is a concept that I thought may be good for powderbed printers, but in a different configaration of course, well done, inovation still lives.

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Random Precision

Very cool. My brother had been messing around with a single head version of this dual turntable configuration, but he's only made it so far as mocking it up in CAD. The internet is so great. Procrastinate long enough and someone else will build it! haha.

Awesome! If you stick a pattern on the bed you could make your machine vision simpler. In fact, you could use no steppers. Are you using steppers?

Edited 1 time(s). Last edit at 07/04/2013 11:57PM by nicholas.seward.

That is an interesting idea. To answer your question, yes stepper motors are used to drive the rotating platters.