When we talk about a radius on the guitar fretboard, it pertains only to the electric guitar or acoustic guitar fretboards. Classical Guitar fretboards are almost always flat or have a bit of a taper at the bass end of the fretboard to minimize buzzing from the upper registers of the bass strings.
Why Use A Radius?
The radius adds comfort for the guitar player. Our fingers are naturally curved or arched, especially when playing bar chords and therefore making a fretboard arched or with a radius makes sense to take advantage of the physical attribute.
You will see exceptions for providing a fretboard radius, especially with acoustic guitars. I, for one, do not like a radius on my personal acoustic guitars. This is rooted in my classical guitar background and I like the consistent feel of the flat fretboard when I switch between acoustic and classical guitars. Therefore the radius is a player preference.
GLS Fretboard Radius Jig:
By far, the easiest way to provide a consistent and accurate radius from the nut to the sound hole end of the fretboard is with a fretboard radius jig, such as the GLS Fretboard Radius Jig. By using this tool, you are able to select from common radii for different guitar types, such as 7.5′, 10″, 12″, 16″ or anything inbetween.The radius can be customized by drilling additional registration holes on each side of the jig.
We have PDF plans for our radius jig located in the Tool Section of Georgia Luthier Supply. This will give you detailed plans for building the jig yourself, so you can enjoy the versatility and accuracy of multiple fretboard radius possibilities and absolute accuracy.
The Fretboard Radius Jig also allows you to make the more sophisticated and challenging compound radius fretboards. These fretboards start at the nut with a smaller radius and gradually expand to a larger radius at the opposite end of the fretboard, giving you a very consistent and gradual taper. The main advantage of a compound radius is edge of the fretboard remains much more consistent vs a fixed radius fretboard where the edge of the fretboard will grow thinner toward the end opposite of the nut. The reason for this is the fretboard width grows in width as it approaches the end opposite the nut.
How The GLS Fretboard Radius Tool Works:
The jig has a simple working principle. The flat fretboard is mounted on top of a pendulum. As you rock the pendulum back and forth, you slide a router mounted on a sled from the nut to the other end of the fretboard. This takes about 5 minutes to complete and all that is required after routing is to finish sand the fretboard surface.
The radius of the fretboard is adjustable by removable pins place into the side of the jig, adjusting each end of the pendulum. We have indicated several radius points on the plans, but you can add your own custom radius points anywhere you desire.
The jig will accommodate acoustic guitar, electric guitar and base fretboards. The fretboards are easily clamped into place with wooden cleats (detailed in the plans) and they provide the needed clamping down-force to keep the fretboard in place. We do recommend that you make sure the fretboard blank is flat sanded and stuck down to the pendulum with several strips of double-stick tape to prevent any bowing of the fretboard during routing.
You can either provide a rocking motion with the pendulum while slowly sliding the sled base of the router progressively down the length of the fretboard, or you can hold the pendulum in place and run the sled lengthwise. Either method works, or a combination of both of them works too.
Construction Details of the Jig:
The areas you should be aware to provide the most precision for this jig are the sled rails and the mounting of the pendulum. The rails need to be perfectly flat and level, which is not hard with proper woodworking techniques using accurate and well adjusted power equipment and final sanding which can consist of sand the top edges of the rails with sandpaper glued to the ends of a 2 foot level.
Accurately fit the sled to your router base. The router should seat squarely in the sled and fit tightly without the need of additional fasteners.
Level the pendulum top to be parallel with the rails. The accuracy of these two elements and how they relate to each other will determine the quality of your radius results.
Do You Want Us To Build One For You?
If you don’t possess the proper tools and or work are to make one of these fine jigs yourself, or if you would like to spend your time building guitars rather than jigs, we can build one for you. Due to the large size of this jig, even when disassembled, both the size and weight make is difficult for us to offer this constructed jig under our current $9.95 shipping policy. if you would like us to give you a quote for the jig and shipping, just shoot us an email and we will be happly to quote this for you. Just log into the Contact US Button on our Georgia Luthier Supply site. We run these jigs on our CNC and quality and accuracy is premium. We will sand all the edges and ship it out unassembled, along with all required hardware (not including the router0.