The Secret History
of the Compound-Radius Fretboard

The story of how this approach came into being involves several participants whom each performed a key role even if it was unintentional. The primary players were Larry Prange, a respected Seattle luthier; Mike Scheel, my close friend and also an extremely talented and demanding player; John Fadden, another talented local luthier and mutual friend; and myself. What about Warmoth you say? Well, the story goes like this:

Mike's guitar of choice was an older Fender Mustang that he felt required having the lowest action humanly possible. This presented an inherent threefold challenge because 1) It had a 7.25" radius, 2) It had a bolt-on neck with typical neck joint area ramping problems and 3) It had a short (24") scale length. Any one of these by itself can make the bending of notes cleanly above the 12th fret while maintaining optimally low action more challenging. With all of these issues, this guitar seemed to present the supreme challenge.

Previous to our first meeting, Mike had taken his guitar to Larry Prange who worked out of Uptown Music in downtown Seattle in 1980. Larry was an accomplished builder and repairman who helped Mike to achieve some of his goal by giving the frets a good leveling and then, from the 12th fret upwards gradually lowering their relative radius by filing the tops of the frets themselves with the mid fret area becoming progressively decreased. This helped to reduce some of the "choking of the note" but it also left little fret height in the middle string area by the time you got to the end of the fretboard. It also left little margin for environmental influences and tended to require constant tweaking. Yet it was a very helpful approach.

A few years went by and it eventually became time to do a refret on it. I'd been doing Mike's repair and mod work for a while at that point and I endeavored to try to take a more satisfactory long-term approach building on the same basic principle. The first obvious task was to level the fingerboard to remove the distortion and ramping that had developed over time. At that point, with the frets out, it seemed only natural to opt for graduating the radius of the fretboard itself in the same area of concern so as to be able to maintain a consistent feel, pressure and clearance within the frets above the 12th fret. I also thought it would be a good preventative measure in case the neck relaxed further in that area in the future. It worked like a charm and was another helpful step forward.

Brian Nelson

Around this same time, a lot of other players (particularly Metal) were also after increasing low action, but they more often than not played bolt-on style guitars with very predictable ramping problems. This provided many opportunities to demonstrate that the "graduating the fret top radius" approach predictably provided the necessary clearance to minimize the problem without having to get in to a full refret. All well and good, but as a builder, it got me to thinking that graduating the fretboard in that area when constructing the instrument just seemed like good insurance against possible future ramping distortion on any guitar while also encouraging lower action capability. Note: Some builders purposely roll off the fretboard height above the neck joint while maintaining the same radius as protection against future neck angle resettling. Not a bad idea, but that often results in a noticeably awkward increase in the height of the strings in that area.

Another element that had been on my mind for some time was how to best satisfy the "rhythm" player who benefited by the tighter radiuses (i.e. 7.25" or 9") because it makes bar chords easier and the wishes of the "lead" player who tended to prefer the flatter (9.5 to 10") radius of the Gibsons. The advent of Jacksons and Charvels becoming popular around that time with their ultra flat (14+") radius fueled the debate even further.

It was the conjunction of these semi-related concerns that seemed to suggest that it might meet all those needs and also seem a little less "weird" to players to just graduate the entire length of the fretboard rather than just one section. Everyone would be benefited and the rate of change in the radius would be so gradual that it would still have a "familiar" feel.

It was at about this juncture that I got the order to build a custom guitar for Mike Rutherford who was on tour with Mike and the Mechanics. That was mid-summer of '86. It seemed the perfect time to put this new "theory" into practice. Although it was to have a glue-in, mortise-tenon (ala Gibson) type neck joint, it also had a 24-fret fretboard that joined the body at the 18th fret and I felt it would be good to do everything possible to benefit an instrument that may see more parts and climates of the world than I'll ever witness. Unto this end I also reinforced it with graphite rods and started with a nice quartersawn length of Honduras Mahogany. Graduating the radius of the fretboard by hand was time consuming, but not particularly difficult. I chose a 7.25" - 10" graduation, because I'm more of a rhythm player who occasionally plays lead and felt that would translate well to Mike Rutherford's playing style as well. After installing the frets and giving the guitar a preliminary setup, I discovered it was everything I'd hoped it would be.

Reenter Mike Scheel, with whom I was in the habit of sharing all my new ideas as he was my closest friend and partner in pushing the envelope of what a guitar could be. He had an extensive knowledge in guitar electronics, particularly pickups (designer of the Carvin M22 pickup and the one who first brought awareness and availability of Seymour Duncan pickups to the NW for starters) and it was always very helpful to bounce ideas off each other. For obvious reasons, he was knocked out when he saw this "graduated radius fretboard" after the experiences with his Mustang.

Enter John Fadden, another very experienced Seattle area luthier, who had also done some very nice work for Mike on some other projects in the past and had become a good friend of his as well. Mike had introduced me to John a few years earlier and with our common interest we were occasionally in the habit of getting together and sharing ideas, especially when they were good ideas so that we might all benefit and prosper and grow the craft. John worked sometimes on his own as a luthier and once in a while for other shops. During this time, John was working for Warmoth Guitars. Well, Mike couldn't wait to tell John about this new development in fretboard design and passed it along. When Mike saw him again soon after that, John told him that he had mentioned the idea to Warmoth. The rest as they say....

It was not long after this that Warmoth started implementing the design into their production although they chose to refer to it as a "compound radius". It's easy to understand why it attracted their interest if you do the math. Think: Warmoth = bolt-on necks = neck ramping issues x graduated radius fretboards = less "choking" issues = lower action possibilities = more customer satisfaction. Warmoth deserves respect for what they have done on their own and, in all fairness, they can lay claim to developing the tooling to implement it on a mass production scale. This ability was, after all, their greatest strength when they were just starting out and trying to compete with the majors. They can also take credit for promoting the concept all over the world so that it has become an important construction and selling feature for many of the most respected and well-known guitar makers.

But it's time the record was set straight and credit given to all those who laid the groundwork for this innovation and brought it into being in the first place. Good ideas don't usually evolve out of thin air. In this case, it evolved out of an untamed Mustang with an ambitious dream, a little time and a bit of horse sense.

The most exciting phrase to hear in science,
the one that heralds new discoveries,
is not 'Eureka!' (I found it!)
but 'That's funny ...'

- Isaac Asimov

 

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