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I'm doing the geometry for a flamenco build (and scooping the solera) and I figure that I can build with no neck pitch and no fretboard taper (7mm fretboard) if I go with a 5mm dome at the bridge. This corresponds to an 8mm string height at the bridge and a 2.5mm action at the
12th fret.

I could get a 7mm string height at the bridge, or increase the action a 0.5mm skoshe, if I taper the fretboard to 6.5mm at the 12th.

Is a 5mm dome too high?

(I know, I know, try it and tell us.)

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Jim Kirby
kirby@udel.edu

Using my neck angle calculator with your figures, I come up with the nut set back from level by 0.5 mm (but that is my allowance for the neck pulling up into relief)

Regardless, I would consider 5 mm dome to be excessive, I think my solera is about 2mm and many flamenco makers use 1.5mm or less.
Ways you can make the geometry work with a lower dome are-
- use a 6mm fretboard
-use a flat or even slightly scooped UTB
-pitch the neck forward 1-2mm and thentaper the underside of the board from 12th to soundhole so it sits flat on the soundboard.
-tapering the board from thick at the neck as you suggested

From memory, I used about 2mm forward set and a 6mm board on the flamenco I built last year, tapered the underside of the board above the 12th. I even (heresy) fretted the board before gluing it on.
If you want a copy of the neck angle calculator send me your email

Thanks Jeff. email is kirby@udel.edu. I usually use a neck pitched forward about 2.5 or 3 mm at the nut on classicals and flamencos, and deal with the fingerboard tapering above the 12th fret to get things to fit. I was momentarily intrigued with the notion of accounting for everything with the top dome because I accidentally scooped my solera out to a 5mm depth (I was looking at the wrong laminate in the plywood), but I'm mightily concerned that the bridge just won't maintain that much of a dome when fighting against the pressed in fans. Particularly since it will be a wimpy, low flamenco bridge.

Probably time for some bondo.

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Jim Kirby
kirby@udel.edu

I'd also be worried that big a dome would make the top too stiff
Yeah bondo works great for soleras, easier to get a smooth scoop than timber

Hi Jim,

I never have built a Flamenco guitar, I only can tell you how my Spanish friend Rafael López Porras (a professional guitar builder in Cádiz, Spain) does it.

He uses a 6000 millimetre solera radius (top radius) which theoretically gives a 3mm dome depth when the lower bout is 380 mm wide, or 2.7mm if the lower bout is 360mm wide ...or anything in between - he doesn't measure that depth of the doming, he relies on the radius of the curved sanding block he used when he made the solera, that's what he works with. The glued on fingerboard is 7mm thick and then he tapers it down until his straightedge (supported by 1mm fret-simulating shims he puts on the fingerboard) hangs 8mm over the top at the bridge location. He says that 8mm is what flamenco players mostly want, but of course he can change that according to the customer's wishes.

Rafael gives his data based on his building experience that is, a typical stiffness of his tops which we know depend on nuances in wood properties, thicknesses and fan bracing details.

I hope this helps, or at least inspires.

I would say 3-3.5mm is the top shelf for 99.5% of guitars. Sure some try 5 from time to time but I've only seen it with people just starting out, and then having a odd tiny bridge on a classical. There is also the issue of the thumb which in flamenco often rests not only on 6th but on the top too. I fear they might find it odd to feel an obliviously enlarging gap towards the soundhole.

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Build log

If I were going to go that high, I would extend the dome well up into the soundhole area so that gap wasn't there. But a few other folks elsewhere have said they think it probably just makes the top too stiff and slow for a flamenco. So I'm flipping over the solera and starting over (or pulling out the bondo).

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Jim Kirby
kirby@udel.edu

Flip it over so you can keep that 5mm side. It's ideal for some FE era Torres style guitars.

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