Bonamens facilitates restringing of old pianos with modern steel wire.

Piano strings are made of steel wire, today mostly of Röslau wire. Old steel wire, used for piano strings in former times, is no longer available. It is now certain that the old wires differ from Röslau wire. Nevertheless Röslau wire is almost taken for granted at a restring of an old piano, sometimes with disappointing results. The use of other steel wire, like the wire of Pure Sound, can result in a substantially better sound. Restrings can be done very much better when the qualities of the old steel wires are taken into account at the choice of new steel wire and at the calculations of the scale.

This site offers a fast and easy way to analyse measurements of length and diameter of strings (or what is left of) of an old piano. The measurements are translated in tensions of possible old string-wires and these results serve as starting point for the calculations of the selected new wire. The results of that calculations are presented in lists and also in graphs, by which adjustments and corrections easily can be followed.
An important starting point at designing the calclation program was making clear the differences between old and new string wires. What kind of steel wire is used in a piano is not visible. The only data a piano betrays about his strings is the length and the diameter. String length can simply be measured, the measurement of string diameters can give difficulties. Sometimes the diameters can not be measured because the strings are missing or because they are too rusty. Gauge numbers happen to be written somewhere in the instrument. Those gauge numbers are not always original, they can be written at earlier restring. Even when they are original, they belong to a certain steel wire and when the kind of steel wire is not known the diameter of the gauge number is not known. So one has to be rather reserved with gauge numbers.
The second important point was to give users the ability to update the data of old and new wire. It is possible that users have other or more sources of wire data. The wire data used in the calculation program are obtained form Pure Sound. When for instance the wire of Malcolm Rose is used like new wire it must be possible to enter the data of that wire in the database of the program.

The claculation program is suitable for the calculation of plain steel strings only. An other solution will be developed for wound bass strings.

Look at menu option "calculation program" for more details.