2016-09-28 (W) Clockwork Theremin SPOKED HUB

Ball bearings are often installed by placing one on each side of a hub so weight is distributed across both bearings and tension from the sides on the axle keeps them in place. If a bearing is secured in place it is possible to get away with only one bearing if the load is small enough. There are other situations of course.

While thinking about a convenient way to use 608ZZ bearings it occurred that it would be easy to print a hub with built-in shock absorbers that would allow some tension to be applied between the gears so imperfections would not cause the gears to slip as much.

A quick design was sketched which was basically a wheel with curved spokes. Not a novel idea but simple enough to create with OpenSCAD and very versatile.

Sketch of spoked wheel hub

OpenSCAD was used to create a parametric model. The parameters which a user can modify are illustrated below. Each of the changes can be made independently but some parameters can exceed the limits of other so when making changes it's important to make them one at a time unless the final dimensions have already been calculated.

For the Clockwork Theremin, a 5" (127mm) hub will be printed. This is the size of a data disc like a CD or Blu-Ray disc.

Possible changes that can be made to the parametric model

A print was made but three different sized spur gears were printed since the final gear ratio hasn't been decided. Having three choices, or more if they are printed, should give a good product with suitable speed and enough power to turn the heavy gears.

Spur gears and internal threaded gear

Parts list:

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.

Completed projects from year 2.

Completed projects from year 3.

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2016-09-14 (W)