An orrery is a small mechanical model of the solar system showing how the planets revolve around the sun.
The first modern orrery was made in 1704 for the 4th Earl of Orrery, hence the name.

The project was conceived by composer Annesley Black. A hand-operated percussion machine drives a simple orrery. The wheels and pointers of this orrery serve as a conductor for a small ensemble. The percussionist / instrument maker Thomas Meixner first designed and built the percussion machine (below). I was then invited to design and build an orrery mechanism to be attached to this machine.

The orrery is raised above the percussion machine so that it is well visible to both ensemble and audience.

• an axle which fits in the hole in the table.
• a trammel with two 0.5 mm slots cut into it (right).
• a sharp knife is jammed in one of the two slots, protruding underneath to cut through the plywood.
• The steel ring is used as a thimble for pressing down on the knife blade while turning it around the axle to cut the plywood.

The gearwheels were drawn full size with a CAD program The teeth were curved with the help of a jig attached to a disk-sander and were aligned on top of the CAD drawings with the help of a radius arm.

The 3mm plywood rims for the pinions were cut and drilled with my CNC machine.
( I use similar constructional techniques when making the wheels for clocks - see here)

The gear wheels are my approximation of the periods of Mercury, Venus, Mars, Jupiter, Neptune and Uranus. Accompanying the percussion machine, the pointers of the orrery guide the ensemble through rhythms that are too complex for conventional musical notation.