R Shepherd Consulting contacted NSF Controls to help develop components for a computer-controlled piano he was working on. The piano recreates Rachmaninoff concerts from 100-year-old recordings.

Richard Shepherd explains:

“When I started developing this system it soon became obvious that nobody’s standard solenoids would be good enough. To my surprise and delight, NSF Controls was willing to create almost anything I wanted. So, we set to work creating a design that suited my needs yet was not awkward for NSF Controls to manufacture. It was a joint effort, and it absolutely achieves the design objectives.”

As part of the overall electro-mechanical equipment designed into this high-resolution piano, a custom set of 88 tubular solenoids actuates the piano keys. With an emphasis on complete mechanical silence, the solenoid’s plungers are polished to the highest quality finish prior to being electroless nickel-plated. This virtually eliminates any mechanical noise from linear motion.

We worked collaboratively to create a new bearing system for the plunger in which very close clearances combined with a soft cushion radial bearing support system were required. With such tight clearances, it was necessary to provide an air breather hole to eliminate pneumatic pumping effects inside the assembly.

Tubular Solenoids

Our tubular solenoids during installation.

The special linear push-shaft extends upwards via a rebound cushion assembly to a threaded head, which allows adjustment with the underside of the piano key. The shaft also extends downwards from the plunger to support a long cylindrical neodymium magnet, which dips into a velocity sensing coil beneath the solenoid; this provides feedback for controlling the hammer velocity.

The 1” diameter tubular solenoids have special end bearing rings with three M2.5 threaded holes enabling the solenoid to be attached to a 10mm thick machined aluminium mounting plate. This not only serves as a communal heat sink but acts as a large mass into which any residual noise forces are lost. The whole plate is rubber-mounted to the piano to isolate any vibration.

Richard Shepherd commented on its performance: “People who hear the performance close to the piano say they cannot hear anything mechanical, just subtle and beautiful music. My own system at home has been in regular use with many millions of solenoid operations and it is still faultless and mechanically totally silent.”

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