If you enjoy the technical side of things, please consider buying my book “Left-brain Lutherie” . Although no longer sold by StewMac, you can buy directly from me.

I enjoy trying to write spreadsheets which are useful in challenging my understanding of a particular problem I’m trying to solve when building ukuleles and guitars. I don’t in any way view these spreadsheets as the answer to a particular problem, or even examples of sophisticated or economical programming, but rather a source of ideas which others can improve upon or modify for their own particular situation. The programs are as error-free as possible, but may well contain mistakes; I would appreciate any mistakes found being brought to my attention so that I can correct them and put the new version on-line for others to use. Thanks in advance for that… I now use Microsoft Excel for all my spreadsheets. It seems more readily available to others. Further, since the files are all fairly small, I’ve also chosen to keep them as Excel format rather than translate them into *.ZIP files… There are many more spreadsheets associated with the programs in the Technology section. Please look from page to page to find out more about them.

Everyone has written a fret distribution calculation based on the twelfth root of two and here’s mine. It grinds out fractional and decimal English measurements as well as metric for any scale length. A usual number of fret spacings are calculated, but of course more can be added using the copy command.

Articles in American Lutherie #s 1 & 13 by Allen talk about various acoustic aspects of stringed instruments. Among the formulas given are those for approximating the air resonance for an instrument of given dimensions. These calculations are approximate but useful in obtaining a beginning understanding of how notes are enhanced or not for different instrument shapes. The frequency of note associated with each physical dimension of an instrument are noted and a look up table is available for noting which nearest notes relate to the calculated frequency of the air resonance. It is interesting to note that the lowest string frequency of a given instrument is often very close to the air resonance frequency.

The relative humidity in the atmosphere has a significant effect on what dimension a given piece of wood has relative to what it was at another time and place. It’s not difficult to measure relative humidity if you have a couple of thermometers or that neat little gadget from Radio Shack. Here’s a source of data to make tables and graphs for using the temperature differences of wet bulb and dry bulb thermometers.

Ukenote (Microsoft Excel file)

Guitnote (Microsoft Excel file)

These two spreadsheets give the frequencies associated with fretted notes for the three smaller sizes of ukuleles (UKENOTE.xls) and for the guitar and baritone ukulele (GUITNOTE.xls). The baritone ukulele is strung like the first four strings of the guitar. Additional octave ranges are given for the G, C and A strings for the ukulele because tenor ukuleles are commonly strung with four, six and eight strings (see Sounds & Strings).

This spreadsheet gives the nominal tensions per unit area of the lower bout of the top and other data in both metric and English units for the four ukulele sizes (three within the tenor size for the three stringing variants) and for a classical guitar. I feel that these calculations can be useful for estimating bracing thickness’ when going from one size instrument to another.

RodBuckle (Microsoft Excel file)

This spreadsheet calculates the pressure Pcrit applied by go-bar sticks of varying diameter and materials properties.