Behold another excellent Great Ball Contraption (GBC) from LEGO enthusiast Akiyuki, this one with Strain Wave Gearing. Akiyuki explains:

Strain wave gearing consists of three components: a wave generator, a flex spline, and a circular spline. Wave generator, flex spline, and circular spline can be recognized as the light bluish ellipse in the center, the yellow cup, and the dark bluish gray outer ring, respectively, in the GBC module.

The number of teeth on the flex spline and circular spline are 32 and 36, respectively. The reduction ratio is calculated using the following formula:

Reduction ratio = (circular spline teeth – flex spline teeth)/flex spline teeth
= (36 – 32)/32
= 1/8.

The wave generator is used as the input, and the flex spline is used as the output…

When the mechanism of interest was applied to the GBC module, the desire was for the movement of the balls to resemble that of the mechanism. I used wave motion of the flex spline to transfer the balls in order to use the strain wave gearing mechanism in GBC module. This differs from the actual strain wave gearing that uses only the reduced rotation of the flex spline as the output.

The chucks attached to the front-facing edge of the flex spline are used to grasp the balls. The balls move in tandem with the wave movement of the flex spline, which is the highlight of the module.

Watch more engineering videos. Plus, don’t miss LEGO Great Ball Contraption: 17 different modules of incredible and GBC at Japan Brickfest 2016.