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i am going to be building a classucal guitar (soon, i hope) and am in the process of visualizing the many steps.. one question i haven't been able to wrap myself around concerns the top radius..

i plan to build using radius dishes.. so is the top completely radiused like i understand the back to be and, if so, how doeas that affect the area under the fingerboard.?. it seems the top should be flat there.. and if it is, how is that handled in the dish?

this is probably a "too simple" question.. i can't seem to find an answer so i'm hoping you guys can help..

jnix, welcome to the OLF, the friendliest forum around!

To answer your question, yes the entire top is radiused. What is generally done is to flatten the area where the fretboard extension goes after the box is glued up. I think there is a jig in the tools and technique section above to do this for you.

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Dave Rector
Rector Guitars

Most guys use a workboard called a solera to build their classical guitars in. My workboard is "dished" only in the region where the bridge is. The rest of the top is flat. Depending on your method of building and your solera the neck angle is adjusted to achieve the correct action at the 12th fret. I hope this answers your question.

Oops, guess I should read a little slower. Completely missed that it was a classical. Listen to what Robbie says, he's an expert on these things.

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Dave Rector
Rector Guitars

I build classicals using a workboard with body area of workboard carved out into a shallow dish. See Courtnalls book "Making Master Guitars" for instruction on how to build same.

You may have difficulties building on a raduised dish if youre using the Spanish Method of construction.

Cheers

welcome!!!

I build pretty much the same as Robbie. Flat upper cross strut & transverse braces. Slight arch in the lower cross strut. Slight arch across the lower bout controlled by the side profiles.

It sure makes life easier when attaching the fingerboard to keep it flat in that area. And remember to just scrap the binding flush under the fingerboard, don't round the edge. Unless you are building in the Spanish method which I don't.

Keep in mind I don't buld world class guitars, just the way I do it.Joe Beaver38964.9209722222

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Joe Beaver
Maker of Sawdust

I build my classicals on a workboard as well. I use the Cumpiano method -- flat workboard with a cork spacer along the perimeter to allow for the top arch. I profile my braces on a dish, though (25'), and glue the braces down using the dish as the base for my gobar deck. But! I do not contour the top tonebar. I leave it flat, and I glue it down separately using the flat back side (plywood) of my dish as the gobar base. The very slight difference in arch between the two tonebars is not enough to affect the top, I've found.

Best,

Michael

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Live to Play, Play to Live

Jnix, you need to figure out what your mode of construction is going to be. You can do it just like steel string builders do, if you are building the neck separate from the guitar. Meaning make the whole top arched. Based on the string height that you will need, though, you will probably find you will have to add a little wedge under the fingerboard extension to get the neck, action, and bridge height to all match up. Consider it a feature - it's an elevated fingerboard, not a gap filler!

Or you can do a hybrid approach. Make all the lower braces curved, but glue the upper harmonic bars using a flat surface. Make the whole top of the rim set flat. This'll put in a slight amount of tension on the lower bout, but that's something you do anyway in classicals - we tend to "spring in" our braces to add tension to the top.

Or you could use a dish to make the whole top rim spherical, then sand the upper bout flat, but that takes experience to get right. You'll probably end up with the wrong neck angle.

You need to tell us exactly how you plan to use the dishes in classical construction, and we can help more.

tell us exactly how you plan to use the dishes in classical construction.....

therein lies my problem.. i'm still chewing on that.. but you've all helped me a lot.. as it now stands, i'll be using a solera as described by a couple of posts...

i'm sure i'll have more questions...

I glue my fans ,or lattice on the top using a 30' dish.
Then transfer the top to a solara dished out as others have said and glue the braces under the fingerboard.
When the guitar is done this actually gives the impression of a forward neck angle -even though I use none.
My bridges end up 8mm tall .

Mike
www.collinsguitars.com
Mike Collins38965.6603240741

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Mike Collins

jnix, in that case, do as Mike states above. This will result in a curved lower bout and flat upper bout. Use the 15' radius (or whatever) dish for the back.

You can use the solera itself to glue in the fans if you dished it out, but like others I like using the dishes for glue up. It's hard work hollowing out a solera to a very even curve.

mike and roger... using your method, do you actualy cut the braces (fan braces) to the 30' radius before gluing or leave them flat and let the glue hold the curve (i'm not even sure that's possible) ??

It is normal to "spring in" the braces on a classical. Use a plane or whatever to make the bottom perfectly flat and straight. Put the top in your dish or solera, and press the fan brace in. You'll notice that it'll bend quite easily. The large braces, like the harmonic bars, I will shape to the curve before gluing them in, they they aren't so happy about bending, and arent' performing the same function as the fan braces anyway.

Some people, notably the steel string makers ( ) will argue with this, stating that we should avoid all tension in the top. Maybe that's true in the SS world. But this technique goes back to at least Torres, and it works. A couple of hundred years later, and his tops still hold their shape, and sound fantastic.

As an aside, if you are serious about classical, get Romanillos' book on Torres. It's not just about the guitars, but goes into great detail about many points of construction and sound, including springing in the braces.

Note that the fan brace won't hold the 30' or whatever radius you are using. It'll flatten out a bit. But, remember that first, you will be gluing a bridge onto the top preshaped to that radius, and second, you'll have 100lbs or so of string tension. The combination will yield the proper dome.

exactly the answer i needed.. thank you very much.. i'll look for the book you mentioned..