Design Progress

This prototype series now stretches across an eight year period. As I honed my craftsmanship and deepened my design knowledge, the workmanship on each prototype correspondingly improved. Each incarnation has improved both the sound and the playability of the interface. Prototype 5 is, in many way a completely different instrument from the early prototypes and prototype 6 promises another leap forward - for the sound, the interface and the potential for distribution.

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Prototype 1 (2007)

This prototype prioritized the ability to change all the key measurements such as keyboard height, key-lever ratio quickly. This work provided proof of concept and led to the patent application. Note the 12 note - single octave compass keyboard.

Despite the basic workmanship there was some good design thinking behind this work; for instance the need for an extended key pivot point was recognized at this stage.

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Prototype 2 (2008)

I worked on this prototype in the spring of 2008; far more robust than prototype 1, it traveled all around Italy and France with me that summer.

Work on this prototype consisted of a complete redesign of the pulley system to provide free movement throughout the system, and a series of experiments to refine the keyboard action with respect to the dampers. This resulted in a double sprung action (the dampers are engaged separately to the keysprings). An octave C was added to the keyboard.

Type 1 Zimmerman production modelPrototype 3 (2010)

The 17 note, custom cut keyboard provides access to a better range of familiar chord inversions, and more flexible melodic playing. It is the first keyboard to be custom cut for the harp rather than adapted from keyboard spares.

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Other work centred on refining the harmonic damping, improving the 3 set pulley system, access for maintenance and experiments with different strings sets and tuning arrangements. This resulted in a strengthening of the bass section, and a defined, fully chromatic melody range.

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Prototype 4 - Virtual (2011 - 2013)

Learning 3d rendering has allowed me to integrate my practice with CNC, laser cutter and 3d printing technology.

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Here I am working on parts cut using a CNC. After the CNC has finished cutting, every part then needs to be extracted from the plywood sheet; the process gives greater precision, but finishing is still time consuming

At the rear left of this picture is a plywood sheet cut using a laser cutter.

Type 1 Zimmerman production model The keyboard box begins to take shape. The precision drilling within each part is a considerable saving - very time consuming with a drill press.

The next two pictures show the difference between the CNC and laser cuts.

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The characteristic burn associated with laser cutting must be minimised, but CNC cutting can also be messy, and not nearly so precise for small parts.

Type 1 Zimmerman production modelType 1 Zimmerman production modelPrototype 5 (2014)


This harp was commissioned from luthier Alec Annes, who innovated upon his own harp designs to produce this 42 string harp.

I built the keyboard action working from the 3d renderings and CNC outputs, using sustainable hardwoods.





Prototype 6 (2015 -)

Type 1 Zimmerman production modelThe next prototype will include innovation on the harp body. Here I have recalculated the string surface using a guitar scale length throughout. Bridging (particularly for the bass strings) is placed on the body and a bass lobe is added to the body around the bridge.

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The keyboard will integrate 3d printing technology. It will still be a wooden keyboard box, but the keys and many of the working parts will be rendered using 3d printed plastic.

This gives a lot more freedom of design. For instance; it allows the size of the playing keys to be rendered independently from the space at the rear of the keyboard. Here, 17 full size keys are tapered to the space of an octave at the back of the keyboard.