Its based on an A-frame and has a hinged support on the rear so that it leans back at the desired angle. Right now its leans at 20 degrees. The rotating disk, which holds the paper, is four feet in diameter. The disk rests on two rollers; one is the idler on the left and the motor drive roller on the right. The disk leans on three casters behind the disk. Gravity keeps it in place. This keeps things simple and not overly constrained. There is no central shaft so the disk center is determined by the two rollers. I used a router with a 24 inch arm which allowed me to cut a very precise circle.
So far it looks like it will work, it rotates very smoothly. Driving on the edge insures that there is no backlash with the big disk and provides a 32:1 reduction from the motor. The NEMA 34 motor has no trouble driving the disk. The controller in the picture is just being used to test the design.
Next is the two 24″ disks which will be mounted above the 48 inch disk. As in my earlier machine the pen arms will connect to the smaller disks with a movable magnet with a short shaft. The two disks will make the whole thing look like a familiar mouse character.
This new design is meant to be suited to display in a gallery or other situation so more people can watch it work.
I have new motor controllers on order. I hope to have it working for the East Austin Studio Tour in November. We’ll see.