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What are the common radii of the top and back of a classical guitar?
Can you incorporate standard steel string methodology using sanding dishes and a mold to get the desired results. (using a bolt on neck)

Thanks,

Ray

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Guitar Building = Continuous Improvement Process

Ray,
The simple answer to your question is; it is complicated.

I believe many classical builders use a flat upper transverse brace and keep the face of the instrument under the fingerboard flat. The rest of the top has a slight dome.

The back is braced similarly to the backs of steel string instruments.

It would be good to look at a plan or a text if you would like to know the tradition of classical gutiar design and construction.

Good luck,

Dave

Typically a classical top is flat except in the bridge to tail area. They are built on a Solera not a close sided mold. The Solera usually will have a recessed bowl area for that area where the fan braces, lattice braces and bridge go that makes a shallow dome in the top. the guitar is built face down with the Spanish heel neck and rim glued up first on to a top clamped face down on the Solera. The back is glued up last in the typical classical construction and is overlaid on a rib structure that has a concave built into it there for the back is traditionally more of a cylinder segment than a dome.

All this said many use pretty much the same technique that steel string builders use. Bolt-on necks mold built rims and dish domed backs and tops but the neck and fingerboards are flat to the upper bouts of the body, no back angle as it is not needed for nylon strings as it is for steel strings

For what it's worth, here are two examples of solera types. In both cases, the lower bout is dished for form a dome @ about 25' or so. The only difference is that in the second one, I have added a raised section which is then dished out, and the sides are then mounted outside the top edges instead of on top of the top edges. It also, because of the raised section, causes a 5mm drop in the top from the sound hole area to the widest part of the lower bout. Just two different ways of approaching the process. They are turned in different directions because one is for a left handed guitar and the other for right handed - just kidding.

You can see how I have been building my guitar at the link in my signature if you have time or are interested. Not saying it's the right way, just the way I have approached the Romanillos style construction.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Ray,

I hear there is some fellow named O'Brien that has some DVD's out that might help answer your question.
In the classical DVD he uses a mold instead of a solera to build the guitar. But he also shows a radius dish for doing the back, although he explains the way to do it by hand as well. The Spanish heel is used for the neck but you could also use a bolt if you like. The top rims are flat but the actual top is glued up in a dish that has been radiused only in the bridge area.

I do mine like Waddy explains and shows in his second picture. The only difference being that I scoop into the base of the solera slight (that is, all the way through the glued on lower bout piece) between the bridge and the soundhole. This puts the highest point of the dome in front of the bridge.

Waddy's journey through his first build should be something everyone who aspires to make a classical guitar should pay attention to. He's gone to the trouble of doing things the way many of the worlds best makers are doing them and he's not cutting any corners. Its very educational.

I tend to use a significant dome for the top, with the upper bout flat and then a 25' radius for the back. I'm planning on flattening the back radius a bit in the future though.

[I tried to reply to this thread yesterday, but the forum went down or something right as I finished...]

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Instagram: @jfrenchluthier
Web: https://www.jfrenchguitars.com/

Thanks for all the comments everyone, they are very helpful!

I took a tour of Waddy's process and all I can say is Bravo, very meticulous and thought out. You should be very proud of your process and ultimately your instrument.

I also took a tour of Kathy Matsushita's 2007 EIR/Redwood Classical Guitar build and it is also very well done. She incorporates a lot of steel string processes in her project and although not a "traditional build", it is a very nice and well built instrument.

I think that with proper material and processes in place there is ultimately more than one way to skin a cat!

Thanks again for the thoughts,

Ray

PS Off to Robbie's site to look at DVD prices! Can never have enough knowledge

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Guitar Building = Continuous Improvement Process

Thank you, Joshua and Ray. It is an incredible journey, and the "education" (overcoming errors and correcting stupid mistakes), seems to grow as the process gets nearer the end.

You are right Ray, there are lots of ways to get it done. Just pick a way that feels comfortable for you. The one that seems most logical to you will probably be the one that you will have the best success with. Sequence is very important, in my experience. Every time I get ahead of myself, or the sequence, I find that I have to go back and change something.

_________________
Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars