Official Luthiers Forum!

Newbie again
This may be a stupid question..
I am aware of the radius to the fretboard from side to side. My fretboards
are currently are 16. A lot of people use a compound radius...
What is that compound radius and where is it?
My fretboards are flat except for the 16 radius. Am I missing something???

Andy

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Andy Z.
http://www.lazydogguitars.com

Hi Andy

You are not missing anything many good guitars are made with a consistant radius all the way down the fingerboard.

A Compound Radius is wher the radius changes at different points on the Fingerboard, the theory being that you get a mor consistent action all the way down the board.

I've been investigating them too. I am sure I have played electrics with compound radii (a long time ago), but was never aware that I had played an acoustic with one. Supposedly, it makes a bigger difference if you (or your customer) do lots of big string bends up on the higher frets of the neck, and yet want ease of playing chords down near the nut. I'm still investigating if it is worth the trouble...

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Should be quite few discussions on this in the archives, some with pics of jigs and such. The GAL Big Red Book volume #3 also has a couple of articles on calculating the appropriate compound radius, if you're interested.

Basically, a normal fingerboard is a section of a cylinder. If the strings were parallel, and not tapering out towards the bridge, a cylindrical section would be the ideal solution. Because the strings fan out a little, they're not an even distance above the fretboard along their entire path, so you can't get them as low as theoretically possible, because they'll hit parts of the board, and rattle. A compound radius board would ideally follow the curve of the string along the entire path, with an even, flat, straight line under each string. Upside to the compound radii, which seem to generally go from about 10" at the nut to 20" at the bridge (And 16"-ish at the 20th fret, like) is that you get a 'rounder', more bar-chord friendly feel at the nut, and low action for easy bends at the higher frets.

Me? I haven't bothered working out the whole compound radius thing. Maybe some day, but a straight 16" seems to work fine for me. I've got a Warmoth strat neck with a compound board, and to be honest, I don't find it particularly more exciting/much easier to play. The only aesthetic advantage compound radius boards have is that, if you calculate it all right, the edge of the fingerboard is an even thickness along the entire length.

Thanks Mattia, excellent explanation and observations.

Jeff

a compound radius does change at different points, an infinite nunber of them. the change is continuous along the board, usually achieved by adjusting the swing arms on a radius sanding jig to different lengths, a nut end radius length and a sound hole end radius length.

they are more commonly found on electrics where the lighter strings commonly used foster extreme bending, but some acoustic builders use them too, particularly those building for fingerstyle players.

where the single radius board is a section of a cylinder, as pointed out above, the compound board is a section of a cone.crazymanmichael38521.6112268519

I wasn't happy with any of the methods out there to create an accurate and consistent compound radius, so I decided to make my own...it only took two years.

Anyway, if you want to check it out at www.cthluthiery.com, it may save you a lot of trouble.

My method for the compound fingerboard radius, you'll have to click the right picture.
At this point I use a couple of locator dowels in the fingerboard and the swing arm along with double sided tape. In the future I'd like to set it up with vaccum.John How38522.9578125

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Tickle your guitar daily, and it'll tickle you back.

It's hard to imagine an easier way to radius a fingerboard, compound or otherwise, than Craig's system. www.cthluthiery.com After seeing it at ASIA, I'm pretty sure even I could do it, and that's probably everyone's least common denominator, or should be. Jerry Hossom38523.4395717593

Jerry,
Again ( hey Craig you need to put me on the payroll or something!),I can attest that it works like a charm. It's consistant and accurate...what more can you ask for?...oh yea...it's easy! Great machine Craig!

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Dave Bland

remember...

"If it doesn't play in tune...it's just pretty wood"

Glad to hear it works great!! I purchased one at the Symposium.

Hey Tom were you holding out on me. I didn't know you bought one. I'd like to get one myself. They worked great and are priced well within the average persons price range. Good job Craig.

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Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Well, after what I saw, I'm dumping my homemade LMI-type unit and I'll be using Tom's until I can afford to buy one of those. It's simple, well-built, and works very well. And the price is pretty reasonable too. Great jig. I recommend it, in fact he's going to give me one if I endorse his product.

Oh wait....durn it, that was another one of them dreams again. Rats.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Hey Jerry and Dave, I knew there was a reason I liked you guys. Oh, and Jerry, if I have to hear one more time from Wendy, "What else did Jerry say?"...
She wished she had more time to talk with you, and to meet everyone else.

Wendy's a smart girl...   

I enjoyed our chats, Craig. Even the ones where you pretended you didn't hear me the first time.    

    I saw the early version of the jig. I plan on making an order soon. I make jigs and I can tell you this is a WINNER. The swing jigs are horse and buggy compared to this.
Yours
john hall
Blues Creek Guitars
He even hs it set up for slotting the fingerboard for the frets.

The jig that does the fret slotting is not the same as the radius jig. Craig had a prototype of the Fret Slotting and Inlay Routing jig. He still needs to do some work on it, but it looks like a very useful jig.