The Shed – September-October 2019

keys from the piano. Soundboards are of
close-grained, light wood such as Baltic
pine, so I rescued a small area of this too.
For other essentials, suppliers were
easily found in the middle of London.
From Smith’s in Clerkenwell I obtained a
series of bobbins of wire between 10 and
20 thousandths of an inch. Making
tuning pins would be tedious, so from
Fletcher and Newman in Covent Garden
I obtained dulcimer pins and a tuning
hammer (key) together with various
gauges of felt strip for damping, etc., and
also a lock for the proposed case which I
used only many years later.

The strings
The pitch and quality of a note depends
on the nature of the string, its length,
tension, diameter, and density.

I experimented with the various

wires on my guitar — up to breaking

point! — to assess the quality of the note

depending on diameter and tension.

On a roll of squared paper I made a

chart to work out an appropriate gauge

and length for a given note, safely below

breaking point but with the tension

adjusted to produce the best sound.

Lowering the tension lowers the note

and vice versa; but if nothing else is

changed, to produce a note an octave

lower, the string would need to be about

twice as long. This would quickly become

unworkable, and that note would be

much quieter. The way around this is to

use thicker gauge, and thinner for the

higher notes.

Brass and phosphor bronze gave the

most pleasing sound. The tensile strength

of phosphor bronze is a little higher so I

used the softer brass for the lower notes,

grading the tension and decreasing

the diameter from 20 thou at the bass

through 18 and 14 with 12 and 10

(phosphor bronze) at the top to minimize

changes in character

Clavichord keys are

simple and short

I cut about half an inch off the back of the

black and white tops and a small amount

off the front. The pivot point is also

necessarily much nearer the front of the

key than in a piano, so a lot of adjustment

was necessary. In particular it meant

moving all the pivot pins, drilling new

holes, relocating them in a new balance

bar, and moving the bushes forward.

This left large holes in the top of the

On my roll of squared

paper I made a full-size

drawing of the most

appropriate combination

for string diameter and

length to work out a

design for a bridge

Left: Finger-jointed frame. Laminating layer

for tuning pins. Angled bridge pins

Below:. Bobbins of wire, dulcimer tuning pin

and ‘hammer’, felts

Left: Recess in frame to hide end of keys.