Adding the 6 1/2 fret to existing fretboard
I have a Folkroots mountain dulcimer that was made in the early 70's. Of course it is without the 6 1/2 fret. I've spoken to a local Luthier (guitar) and he of course cannot add the fret without the correct mathematical measurements.
My fretboard is 29 1/4 inches from nut to bridge. Can anyone tell me how that would be calculated?
Or of a dulcimer Luthier near Tallahassee, FL. I don't want to be without it for a long period of time.
Thank you for any input!