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Sorry for asking such a stupid (!?) question. I need to understand how this works.

In Bogdanvich's book (Classical Guitar Making pag. 56) I found this 2,5 mm under the solera level at the nut position and aprox. 2 mm over the solera level at the brige position.



In Courtnall's book (Making Master Guitars pag. 165) I found 3mm under under the solera level at the nut position and aprox. 2 mm UNDER the solera level at the brige position.



It looks for me that for the same dimensions of the bridge+saddle, one result is a very big difference in action beetween the two models.

Thank You for any kind of answer.

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mihai,

It's been a long time since I used either but I did build my first two (back in 2004) using the Courtnall book and, if I recall, the angle worked out well.
I also built my second two following, more or less, JB's methods. If I recall, the neck angle on the first ended up OK but string height was on the low side for what I like on a classical-probably great for a flamenco. For the second I shimmed the neck end on the solera by 1mm (flatter/less angle) and ended up pretty much perfect.

Again, this is the best I can remember of the two (I haven't used either method since 2007-8). Also, this is purely anecdotal-those were my first four guitars and my skills weren't what they are now. I'll add, too, that I used my own design for all of those. Even though my dimensions were very similar to JB's they weren't exactly the same so that could possibly account for the string height ending up a touch on the low side for the first...though I kind of doubt it: I used the same scale length and the lengths of our bodies only differed by a couple of millimeters.

I think you'll be fine using either but I'd definitely pick one method and use it all the way through. Don't mix and match pieces from each method on your first.

Edit:
Also, I don't have the book in front of me now (it's at my shop) but, with the 25' radius dished out of the ramp, I don't think you're anything like 2mm over the main plane of the solera at the bridge position...I think you're pretty close to AT the plane of the solera (close to 0mm).

Thank You for your prompt replay !

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mihai,

I've been building with solera for almost 50 years and although I've seen both books I can't comment on their value; however Courtnall's drawing looks more like what I would recommend. We don't use a fixed neck angle for the deflection. I've found that it's better to lock the guitar in a jig and measure the deflection carefully on each guitar using shims to make adjustments to achieve the desired amount. It's critical that the guitar and neck are held rock solid before putting on the back.

The JB version I believe is more Romanillos style.

The JB solara has the bridge on the same plane as the upper bout and the doming is created by dropping the top at the tail.

The Courtnall solara is a more typical one in that the rim of the guitar top remains in a plane and the doming is centered within it. This raises the bridge.

Either way, a good way to think about your geometry is to add the neck angle and the amount of doming, (ie the amount that the top rises above the plane of the guitar rim), so that the total equals 5mm. This will give you about 10mm from the guitar top to the top of the saddle and wiggle room to set your string heights at about 4mm at the 12th fret.

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Whichever way you go, you also have to take into the equation the taper of the fingerboard. I use a 3.5 mm drop at the nut and a raised lower bout similar to Bogdanovich. Then I taper my fingerboard 2 mm on the treble side and 3 mm on bass side.

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Waddy

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