What is the best way to rotate a circular disc?

Question

I have a project that needs to rotate a clear circular disc, it is critical that I do not obstruct the viewing area of this disc. Can someone please suggest some options? I am envisioning something that would involve some bearings placed along the edges of the disc, but I am not really sure.

The disc to be rotated will be in a vertical orientation.

Answer 1

If your intent is to not see the drive mechanism and/or keep the center unobstructed then I think your idea is spot on...

To keep the disc centered with a minimum of hardware you would use three bearings spaced 120 degrees apart around the circumference.

To drive the disc you could either replace one of these bearing locations with a driver or add a fourth location from which to drive the disc.

i would opt for the latter method, three bearings to keep the disc centered and take radial loading and a fourth location from which to drive.

You will also need some bearings to support the weight of the disc and its contents in the axial direction (thrust). (example:look at the roller ring under a glass turntable of a microwave) You did not mention how the disc will be oriented, vertically or horizontally. If vertical you will need additional thrust bearings to keep the disc from falling forward.


There are several options for driving the disc:

1.) belt drive using a groove in the circumference and a pulley on a motor shaft.

2.) friction drive where a capstan (soft rubber on a shaft) mounted on the vertically mounted motor shaft. This capstan rubs against the edge of the circumference.

Answer 2

Go for three edge-fitting pulleys at 10 o'clock, 2 o'clock and 6 o'clock. The 6 o'clock one is a fixed idler. The 10 o'clock one is a fixed driver. The 2 o'clock one is an idler on a pivoted arm, with a weight or spring to keep it pushed gently against the rim of the disc, and the disc pushed against the other idler and the driver.

This will work a lot better than three idlers and a driver, where it would be too difficult to share out the load approximately equally.