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I've been looking back at discussions on the topic of compound radiusing for fretboards, and I think I'm going to give it a go on the build that's currently on my bench (I've been doing a set radius so far). IThe idea makes a lot of sense, in terms of achieving a more desirable string height off the fretboard, and it doesn't seem that it would be too much more difficult than making a fixed radius.

Now I'm wondering what type of 'range' do those of you who are doing compound radiusing end up with, from nut to end of fretboard. Is it something like 14" to 20"?

Thanks in advance for any info and/or suggestions,

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Ken Mitchell
Durham, NC

Mine usually go from 16" to 22" but it's really just a matter of personal preference.

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http://www.chassonguitars.com

Ken, it has alot to do with personal prefernce, like Kent said.

Mine start at 12.5 @ fret 1 going to 17 @ fret 20, but it depends on a number of factors including taper of the board. You can calculate your radii here:

http://www.stewmac.com/freeinfo/a-compoundradius.html

Chuck

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12" at the nut, 16" at the 12th fret.
First compound I tried and seems to work for me.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Thanks for the info, guys! I'm going to start working on a fretboard.

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Ken Mitchell
Durham, NC

It is almost too nit-pickingly pedantic to even mention it, and it makes no difference for practical purposes, but it is nonetheless a fact that at every point along the fretboard the profile as described by the StewMac article will be elliptical rather than the arc of a circle.

Paradoxically, a true "conical radiused" fretboard is not a surface which lies on a conventional cone.

Wow... OK, I know that I've got some fine finishing to do still, but my first attempt at this seems to have gone surprisingly well!

I roughed out the radius with a long, 18" wood plane, with the help of a few pieces of binding tape staggered along one edge to add a radius effect. Keeping the plane parallel to the edge I was working on, I could watch the shavings and see what I was taking off (along with some pencil marks for additional visual backup).

Then with a long sanding block, followed by a Stew-Mac 16" fretboard leveler, there was actually very little contouring to do!

I wish I'd paid more attention to this idea 5 years ago. I think compound fretboard radiusing is going to be a nice improvement to my building chops.

Thanks again for all the suggestions!

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Ken Mitchell
Durham, NC

25.4" scale length: 16" nut, 20" 12th fret, 24" saddle...

Can you use other words to describe this in a bit more detail? I don't fully understand how you accomplished this especially the part about using the binding tape.

It doesn't matter if the true shape of the fretboard is circular or elliptical at any given point along the fretboard length. The purpose of the compound radius is to put each string in it's own individual straight fret plane, so to speak. It's a fact of geometry with a straight radius fretboard that when the center of the neck is straight, the sides will be bowed back slightly due to the trapezoidal configuration of the fretboard. The tighter the radius, the more pronounced the artifical backbow will be.

To ilustrate, get a piece of posterboard, draw a fretboard profile on it, and roll the posterboard into a cylinder with the center of the fretboard lined up lengthise straight up and down along the side of the cylider. Then run a straightedge parallel to the "fretboard " edge, you will see that even though the center of the fretboard is straight, the straightedge will rock on the edge of the fretboard.

Now shape the fretboard into a cone, and you will see that each string falls along a straight portion of the fretboard if the cone is shaped properly.


THAT'S what makes a compound radius effective.

As far as the individual radius of each fretboard, it doesn't matter unless you are building a guitar with a Floyd Rose locking bridge, in which case the nut must be 10" to match the lock nut, increasing to 16" at the end of the fretboard, so that the "cone" will terminate at the bridge at 22" to match the bridge radius.
If you get the radius a little off at the nut it's not good, but the bridge saddles can be shimmed individually if you get the end of the fretboard off.

I do compound radii using my belt sander which has a 30 inch sanding platten, checking with radius gauges and straightedges as I go.

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Old growth, shmold growth!

I built a router fixture that was developed by Rick Micheletti http://www.luthierscooltools.com/Dwgs.htm#FB%20Radius%20Jigand it works great. With it you can easily change the radius at each end of the fretboard depending on what the customer wants.

Chuck

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"To live a creative life, we must lose our fear of being wrong"
- Joseph Chilton Pearce