Questions: Scale Length

by R.M. Mottola and Tim Olsen

Originally published in American Lutherie #93, 2008

 

Byron from the Internet asks:

Is there any way to determine the scale length of an instrument from a piece of the fingerboard? I have the fingerboard from an instrument that is currently being restored. The nut end had been trimmed, I think to accommodate some kind of odd nut.

The Questions column editor responds:

All inter-fret distances are related to scale length, so measuring, say, the distance between the 1st and 2nd fret and then looking that up on a fret scale chart will tell you the scale length. Or measure the distance between the 7th and 19th fret (assuming the instrument has a 19th fret of course) and multiply by three. The result will be within a few hundredths of the actual scale length, close enough to identify it.

American Lutherie editor Tim Olsen responds:

Imagine you put a capo on the 1st fret of a functional guitar. Measure from the 1st fret (now functioning as the nut) to the 13th (now functioning as the 12th), and double that to find the mathematical bridge point. If the fretboard is still on the guitar, you can find that point near the saddle and mark it. If the fretboard is not on the guitar, you can clamp it to something, like a 2×4, and mark the bridge point on that. Now you could easily find the nut point by measuring from the newly marked bridge point back to the 12th and doubling it. Confirm it by calculating the scale and checking the position of the individual frets. ◆