## 4 Foot Scale

Values for the string scale are calculated from the formula 10log ( l2 * n2 ), where l = sounding length of the string in cm and n = frequency of the string in Hz. This type of string scale curves was introduced by Hubert Henkel (Clavichorde, Leipzig 1981, pp.108ff) and is independent of string materials and string thicknesses.
Calculations are made from the a1 frequency specified in the diagram.
If sounding string lengths are doubled for each octave the curve will be horizontal.
The coloured lines can give an approximate idea of breaking points for different string materials. The red line corresponds to red brass, the yellow line to yellow brass and the grey line to iron.

## 8 Foot String Length

The vertical lines show sounding string lengths. All C-strings are red all F-strings are blue.
The raster is shown according to the setup in Raster Settings...

## 4 Foot String Length

The vertical lines show sounding string lengths, if the clavichord has a 4-foot. All C-strings are red all F-strings are blue.
The raster is shown according to the setup in Raster Settings...

## 8 Foot String Gauge Numbers

Most of the Swedish clavichords have string gauge numbers. The 8-foot numbers are written at the tuning pins. Later instruments have wound strings in the bass. Only exceptionally (N83583) there are gauge numbers for the core wire of the wound strings.

## 4 Foot String Gauge Numbers

The gauge numbers for the 4-foot strings are written at the hitch pins on the soundboard.

## 8 Foot String Tension

The curve shows string tensions in kilopond. String materials and string thicknesses must be known for the calculation. Most Swedish clavichords have string gauge numbers showing thicknesses. Covered strings in the bass have no gauge numbers and are not included. If string thicknesses are unknown the curve in the graph and the values in the table are lacking.

## 4 Foot String Tension

The curve in the graph and the values in the table show string tensions in kilopond, if the clavichord has a 4-foot and string thicknesses are known.

## String Angle

The diagram shows string angle deviations from a straight line at the bridge pins. When the circle is empty the angle is negative. Strings that are back pinned are not shown.

## Key Balance

In playing a key is moving up and down with the balance rail and its pin as a fulcrum. If the front part is from the key front to the balance pin and the back part is from the balance pin to the tangent the value shows the relation of the front part to the sum of the front and back part. As the sharps are shorter than the naturals the diagram will show two different dot lines.

## Rack Pattern

In the back end of each key is driven a pin or a blade which slides in a vertical slot cut in the rack, glued to the inside of the back of the case. In later clavichords the slots are substituted by slips of wood between the key ends. The rack with its slots or slips of wood defines the position of each key and hence the left end of the sounding part of a string. The rack pattern is thus an important part of the maker's design. The back end of the keys must be made narrower towards the treble. To construct the corresponding rack pattern a measured distance was divided in a certain number of equal parts. The following measured distances were divided in the same way. By choosing distances and number of equal parts in each distance the maker could make a rack suitable for the appropriate sounding string lengths. It is often possible to reconstruct the maker's choice of equally divided distances. For some of the clavichords such a reconstruction is made.
The first line in the diagram always shows the measured pattern. If there is an interpretation of how the construction was made, there is an additional line showing this reconstruction. The inch values used for that calculation are written below the line