There are a few online fret calculators that will give you the fret spacing for any given scale length.
Wfret is a windows only application....there are a few emulators that allow you to run windows apps on a mac. There are probably a few good fret calculators that run on a mac OS.
Maybe some help here...
the calculator is done in MS Excel, you can change the distance between the Nut to the Bridge and it will update automatically.
I just tried to use the fretfind2d calculator and couldn't get it to work. I've used it before and loved it. Don't know what happened to the site but glad some one made a file with tons of scale lenghts. It's a life saver.Thanks Randy Webb
I just tried it and was able to download a pdf of 25.5 scale length, 24 frets, .25 inches fret overhang and 1" string width at nut & bridge. What you do is scroll to PDF (multi page), click Save to Disk and choose where to save it on your computer. I already have all the scales I usually use saved as a PDF and open them to print the template. I print it, tape the 2 pages together, trim it to size and use a light coat of spray mount to put it right on the fretboard. I score the fret lines with a razor and then use my Harbor Freight pull saw to cut the fret slots. I also use the template to mark the nut and saddle slots and cut those with an Xacto saw and finish with the torch tip cleaners.
If it doesn't work for you let me know what specs you need and I'll send you the PDF to print.
FretFind2D is hands down the best!!!
EDIT: I just added FretFind2d.webarchive to the post up top as an attachment. It downloaded it to my computer and when I clicked it and worked, not sure if it'll work for anyone else.
I got it to work on my older computer but I did find that it printed it out of scale. I'm trying to build a fretboard with a 25.5" scale. But the 12th fret always comes out at 12.25". Shouldn't it measure 12.75"? Any thoughts?