Multi (Compound) Radius Fretboard Sander

[Barry Meyer]

Sometime in the early ’80’s I started making electric guitars as a hobby. I happened to know Denny Rauen as we’d gone to the same high school, and Denny had a musical instrument guitar repair shop in Steger, IL. I showed Denny some of my early efforts, and he was very encouraging and willing to share his knowledge. Two key things Denny shared with me. He described his multi radius fretboard discovery, which at the time he implemented by reshaping the fretboard radius by hand. He also described a trapeze style fretboard sander he was familiar with which swung the fretboard over a belt sander to sand the radius. This was a constant radius. I thought, why not just have the machine sand the multi radius. The manufacturing plant I was working at was constantly throwing stuff out, and I would scrounge interesting garbage that I thought I could find a use for. The result is the multi (compound) radius fretboard sander shown in the picture. To the best of my knowledge, this is the first multi radius sander built, although someone else could have built one without me knowing. The picture shows a setup with extremes at the nut and body end just to show the flexibility. You’d never actually make a fretboard to those extremes (at least I wouldn’t). The fretboard was already glued to the neck, the neck shape was roughed out but enough material remained that the neck was held in place with pointy screws. This left indentations, but that wood was removed when the neck was finished. A small amount of tension was put on the truss rod before sanding as this seemed to work best for tension set up after the guitar was finished. This arrangement made very nice multi radius fretboard necks, although it was underpowered and the drill press style drum sander parts I used to drive the sanding belt were prone to slipping. It did however work and is similar in design to commercial fretboard sanders that eventually became available.

[Randy Roberts]

Additional views, and maybe a step by step of it's use might be helpful. I'm not sure I get it it from this one picture...

[JC Whitney]

That's pretty slick, especially for it's adjustability on the fly.

Your post has had me racking my brain for a similar setup I saw way back when... the cobwebs eventually cleared enough that I remember it looking something like this:



Belt sander on the flat, with a loose caul and handle (in white above) to which two radius forms were screwed (blue and green) - one with fretboard's nut end radius, one with body end. Fingerboard was temporarily attached to the underside of the caul and the whole bit wobbled about on the sander to impart the radius.

[Barry Meyer]

There aren’t any more pictures, and this was disassembled in the mid ’80’s so there won’t be any more. It would be difficult to build it as shown because as I said, I used components that my employer was throwing out. As a result, some of this was over designed with components which, if purchased new, would have been unnecessarily expensive, and some of it was under designed, because I used what I could get for free, or cheap. There are a a number of different ways to do this that can be found on YouTube. Some work better with just the fretboard, vs. the fretboard already glued to the neck. Some use sanders, some use routers. I think having the fretboard already glued to the neck is an advantage, since you can pre-tension it and sand it flat. This style could be used to sand a fretboard glued on a neck thru body design (before gluing the body “wings” on), or a fender style all maple neck.