Helpful spreadsheet I concocted for those interested in figuring up fretboard geometry. It will calculate fret locations (though you probably won't use those), fret slot depth taking radius and taper into account (i.e. it calculates the Sagitta based on the radius and widest part of the fretboard), and will calculate proper taper to maintain even spacing of the string to the edge of the fretboard. It will also take string width into account when doing that. That is important because you specify the clearance from the edge of the string to the fretboard, but most bridge manufactures specify string spread based on the CENTER of the string, so you can end up off by almost 1/16".
It also calculates the proper taper settings for my style of taper jig. I'll take some pictures and post that later on today, but it makes for VERY simply tapering setups.
http://www.ballofshame.com/GuitarCalculatorV1.xls
The current setup in the spreadsheet is a sample for a reasonable spec on a 25" scale length acoustic (1.75 nut). Just change the input settings to match what you have.
notes: you don't need to specify fingerboard length if you don't want to, but you DO have to specify the last fret. The calculation for the slot depth needs this in order to calculate the proper maximum depth as the depth gets greater the more frets you have do to the radius and the taper.
Generally, I end the fingerboard at a fret location, so if I have 22 frets, my fingerboard ends at the 23rd fret, and where it says "Fingerboard Last Fret" I would enter 23. Some people like to extend the fingerboard longer. That's why you have a choice of specifying a last fret AND a fingerboard length. It your choice how to perform the taper. The spreadsheet will calculate both. The only place it really makes a difference is in the calculation for my taper jig. It needs to know not only the taper, which would really be specified anywhere, but also the maximum width of the fingerboard, so it needs to know how long the fingerboard will be in order to give the proper settings for the taper jig. When you see the taper jig in action, it will all become clear. The tapering part of this and the jig can also very easily be adapted to tapers on things other than guitar necks. I find the setup and calculation far simpler to get right using this technique than those traditional tapering jigs.
Keep in mind that this is version 1. Use at your own risk. I'd like to eventually expand this to include neck angle calculations and possibly some other useful calculators as well.
Feedback is welcome. I hope someone finds this useful.
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