Multi-Radius Fretboard

By Denny Rauen

String Instrument Craftsman May/June 1988

American Lutherie #8/Winter 1986

Multi radius fingerboard? What's that? It simply means that a fingerboard tapers from one radius or curvature to another. This gives a guitarist great mobility on the fingerboard and remains a comfortable feel for chording. I developed this idea in 1978 while refretting a Fender Stratocaster, and I owe some credit o the guitarists who remarked "I want my Strat to play the same as my Les Paul." He was referring to the string action of his Les Paul being lower than his Strat. At the same time, I was employed with a company building electric guitars and basses, while developing my repair knowledge and skills on the off hours. His request seemed to present no problem, so I refretted the instrument and moved to final setup. With the strings set very low, it played great! That is, until I tried to bend a note. The sustaining note died immediately because there was not enough clearance down the fingerboard to allow the string to vibrate. I realized then Gibson used around a 13" radius and the Fender was a 7" radius. It was going to be necessary to change that small radius. I have always liked the feel of a smaller radius fingerboard for chording. Instead of flattening the entire fingerboard I worked on retaining the small radius at the first several frets as much as possible. I started increasing the radius at the end of the fingerboard by gradually tapering the radius of the fingerboard to be more like a Les Paul. After many hours of experiments, it was obvious that the radius could be changed into what I call a "multi-radius" or maybe an easier way to understand would be to think of a cone shape and how it has a very small radius at one end, and a very large radius at the other end.

I accomplished this experiment by drastically altering new frets I would install on an old guitar. Upon restringing the guitar and playing it, I would get a feel for where things were going. Realizing that the multi-radius idea would work, I removed the frets and altered the fingerboard to a 15" x 7" radius combination. This turned out to be very playable and allowed for the note bending I was looking for! This combination changes from one player to the next, depending on what action levels and 'feel' they require.

Multi-radius fingerboards are standard with my own custom builds and refretting work. For the guitarist requiring extremely low action, I think you will find multi-radius fingerboards to be the ticket.

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My reply to often asked questions about publishing this idea:

Multi-Radius fingerboard, or these days often called 'Compound Radius' was something I invented in 1978 and became a standard on many of my custom built guitars and refret work. I am often asked why did I publish the idea and not patent it? At the time, I was encouraged to do so by fellow guitar builders Barry Meyers and Dave Peterson. Barry had even worked up the math formula for the cone shaped fingerboard and altered an apparatus I designed for producing fingeboards so it could also produce the multi-radius fingerboard. I did look into getting a patent and though it may sound simplistic, I just decided to share the idea. Some have said 'that's the old hippie in me'. I think they are partially right. The knowledge that I gave something back to the community that I have gotten so much from, is truly special.

In the spirit of sharing information, I have published other ideas on the web site and will continue to.