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Hi everyone

Kevin Ryan once told me he doesn't arch his soundboards because he
hasn't had one dome up on him. Not arching the soundboard would
seem to take away a few steps and make a few more easier. I'm
interested in a couple more voices on this. What would you say the cons
are of not arching the soundboard?    

The biggest con I can think of is the guitar's soundboard will be more prone to cracking or splitting if it is exposed to an excessively dry environment for even a relatively short period of time. Heat can do it too, but I suspect that's more a function of the top losing moisture faster at higher temps.

If a guitar with an arched top is exposed to low humidity, the arch will begin to flatten out. If the arch is not there, the wood fibers become stretched cross-grain and cracks are likely to develop. Having a soundboard "dome up" would be the result of being exposed to higher than optimum humidity, but this is generally less of a problem, unless the wood fibers actually beccome crushed as they are compressed together due to expansion.

The way I see it, having an arch already established allows the top to flex either way easier, hence reducing the risk of premature failure.

Best,

Michael

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Live to Play, Play to Live

For me, I see two additional factors to the comment Mike made...

The Larson Brothers (prewar builders)arched their tops, and an awful lot of their instruments are still in good shape.

I also see it as prestressing the top. Similar to the way iron rods in tension are used to prestress concrete, making it much stronger.

Martin had the top radiused from the get go. I have a 1888 00-28 with a top radius.
   There are 2 reasons they do this. One is for strength. The 2nd is to allow for top movement in humidity changes.
    Top infamous martin crack wasn't from the shringage of the top but from the pickguard. In the olden days the pickguard was put on under finish. This was adhered straight on the wood. As the wood dried and the pickguard didn't the top cracked at the pickguard. This is known to this day as the martin crack.
    john hall

The man I built my first guitar with, Brad Nickerson, does not arch his flattops. I was fascintated by this and specifically talked with him about it. He's built a few hundred guitars now, and says he has never had one come back for any kind of repair related to a humidity crack in the top. Not that it cannot happen, but it can happen to radiused guitars, too.

Oddly, he believes the exact opposite of what Michael said, namely that "not" artificlly arching the top actually allows it to flex in both directions easier than if it was arched. I'm a newbie, so I have no experience...but it's hard to argue with Brad's sound...or Kevin Ryan's for that matter. Plus, who really buys a multi-thousand dollar instrument, and then doesn't treat it properly regarding humidity? It's so easy, even a caveman could do it.

More than one way to do things I suppose. And my first guitar? No arch.

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Eagles may soar, but weasels don't get sucked into jet engines.

if you've spent a few years in the repair game you know that a lot of folks spend their thousands and don't take the time to properly care for their instruments. the old more money than sense syndrome...

   I have seen guitars both ways. I have seen few Flat flat tops that don't crack. Here is why the tops are arched.
1 st strength
   2nd movement ( if it shrinks the top sinks and will crack no matter what you were told. I have seen and repaired too many guitars )
   3rd with the radius this makes the 1t neck angle work better.
   Yes you can build flat but I can bet you will see a problem down the road. Humidity can cause the tops to move a good bit.
   All builders that I hang out with that do this professionally will dome the top. Rememeber the top will expand a good bit from dry season to wet.
   Have fun building
john hall tippie5338885.3975231481

I hadn`t thought much about this until now, but wouldn`t a raduised top be beneficial to the action later down the road? I`m thinking it would provide a happy medium when the top does it`s changing, and still keep the action within some sort of tolerance.
I shuddering at the thought of the strings laying on the 20th fret when in one place and then finding them 1/4" above it in another location/enviroment.
Maybe I`m just blowing smoke rings, here.

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Give me 50 cents worth of regular.
Check my oil too, if you don`t mind,,,

Brad Nickerson's flat top guitars are very stable. I built my first
guitars with him as well. He puts a finish on the inside of his
guitars, top back and sides, but not on the braces, blocks or linings.

I can only think that putting a light finish on these surfaces would
help the instrument stabilize more slowly to climate changes.

The only drawback to this inside finish that I can see is that it could
make it more difficult to repair cracks in the future if (and when!)
they develop.

Any thoughts??

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- Louis Freilicher

Oh No! Not another learning experience!

In addition to stability under tension and forgiveness to lack of humidity
control, I have always considered tone a primary reason of radiusing a
top. Piano makers have always considered what they refer to as the crown
of the soundboard as key to shaping the tone. If you go in to many piano
shops they will often have a small demo soundboard with a tuning fork
mounted to it, and an adjustable arch to the top to demonstrate the tonal
importance of keeping your soundboard humidified.

I can't imagine myself ever building a true flat top. To me they generally
sound rather sloppy and shapless (yes, even those from a number of well
respected current builders). Of course that's my own opinion, but I know
many customers who bring thier dried out guitars in tell me the tone
seemed to spring back to life after being rehumidified, and the top
returning to a good radius.

I suppose it could be well though of as part of the bracing, given that a
compound radius stiffens the entire board and so effects the way you can
design and voice your bracing. I am a very big fan of 30's Gibsons in
which many tops appear to be an astonishing 18'-20' or greater radius,
with relatively light bracing. These guitars generally have also remained
much more stable and survived better than other flatter topped guitars
from the same era.

_________________
Eschew obfuscation, espouse elucidation.

I'm appreciating the discussion. I think it can be educational. If I were to
play devil's advocate, I would wonder why, if it's such a garaunteed way to
have a cracked top, Kevin's never had an issue? He's close to 100 guitars
a year I believe.    

I wonder how rigidly Kevin braces his sides. It seems to me that if a guitar's sides are not braced against either the back or top in a solid fashion, such as to maintain their own perpendicular orientation, then they can flex in and out (+ or - from perpendicular) as a way of ameliorating the movement of the top as it shrinks and expands.

Best,

Michael

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Live to Play, Play to Live

On a true flat top wouldn't the string tension pull the soundboard into a small dome or arch, or at least a little belly behind the bridge? Maybe this could be where the give and take of environmental changes gets accounted for. Or maybe if you did not tuck your baces under the lining that would allow for some movement. I don't know, just thinking out loud.

Jeff

Sometime ago, "somebody" said that Kevin Ryan doesn't use side braces. I have no idea if that's accurate. Anybody know?

_________________
Eagles may soar, but weasels don't get sucked into jet engines.

[QUOTE=Bill Greene] Sometime ago, "somebody" said that Kevin Ryan doesn't use side braces. I have no idea if that's accurate. Anybody know?[/QUOTE]

Based on the handful of 'contruction' pics I've seen of Kevin Ryan's guitars, yup, no side braces.