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I spent half a day making this finger board radius jig. I got the inspiration from the book "Lutherie Tools" (available form LMI). I'm sure there is something like it on the forum here somewhere also.
I guess this is a case of the proverbial cracking a walnut with a sledge hammer. It is by far the biggest jig I have now. I am going to have to build a small shed out the back just to store it!!




Fingerboard is attached with double sided tape.
The outer adjusters are used to set the fingerboard radius required.
The inner adjuster get the height of the f'board adjusted so that centre on both ends just sits on the router bit.
...40 swings later - all done.
Incidentally- bit of ply under the 3rd pic was my test run. I must admit I was a bit anxious when doing the real thing.

For others relatively new to this work, I would recommend the book "Lutherie Tools" produced by Guild of American Luthiers. When my wife wakes up at 2am and finds me still reading this book, she thinks I have totally lost it. It has lots of great ideas and information, much of which I am sure is on the forum somewhere.

Frank

I like the simplicity of mine.


and i don't feel the need for stowing it away.
the rod is epoxied to the bench and attached with spherical bearings for the router 'sled'.
haven't yet built a guitar, but i've radiused a couple of fb's with this works great.

I was inspired by a thread by Dave Fifield who in turn was inspired by Mario(I think)

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Frank

Nice job Frank!

And nice job Frank!

Very inspirational!

Yep, the old fingerboad radius dilemma...

I'm lucky enough to own a drum sander so I've made a jig (if such a simple and effective device can be name thusly) just like Sylvan Wells.(tips and jigs section).

Simple, effective and very easy to store.

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I'd like to be able to prove, just for once, that money wouldn't make me happy...

I have Sylvan's in my shop too...I love having the floor space for once now that all the machines are gone...now at least if I trip I have room to fall!

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http://www.presnallguitars.com

Does Well's do compound radius boards? And the same for the first jig?

The first jig won't handle that in its current form. I would need to put a hinge mechanism on one of the outside posts so that one end stands higher than the other.
When you use a compound radius, how much does the radius typically change from end of fb to the other, and is the change linear i.e. constant ?
Frank

After looking at it I think for it to do a compound radius the whole frame would have to slide forward and back and not slide on the conduit. The radius is constant from nut to end. Think of it as a section of a cone.

Nice work Frank and Frank.

The first one from Frank V. does look a bit big, but that mainly comes from the size of the main frame that holds everything up being almost twice as long as a fretboard by the looks of it - maybe you could shorten it Frank?

Second one from Frank A. looks familiar You're right Frank, I got all the ideas for my version of it from Mario (Grumpy). I'm still looking forward to seeing his new system....I don't think he posts here any more though Your version looks simpler than mine. I have made a couple of mods to mine since I posted it. The main one is that I've added some platform "stays" (actually, a couple of these things with the screw replaced by a small adjuster knob), one at the back and one at the front, so that I can set the swinging platform where I want it, lock it in position, then have two hands on the router. It's much more predictable/stable like this.

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

A cone doesn't have constant radius!

The change in radius on a compound radius board is indeed linear. It depends on how you do it, though. The boards I make are usually a swept surface between two 'true' arcs rather than a section of a cone. They still have straight string paths, but the vertical sections are actually true arcs (which they won't be with a conic section).

I'm waiting for Mario to 'out' his new system, as well. I know the process, but the Devil's in the details and I've heard it can be a bit 'finicky' . I think it might catch on, if he gets the quirks worked out and feels like making it public.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Yeah, I ment that it was changing constantly from the nut to end or linier as you put it. I think it was the way he stated the question.