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[QUOTE=JohnAbercrombie] [QUOTE=Hesh1956] This I believe acts a a buffer to swings in RH and adds stability.[/QUOTE]
A large stash of lumber will also act as a 'moisture buffer/reservoir' to some extent.
This is a great way to justify your WAS to spouse and family!

Cheers

John
[/QUOTE]

Brazilian does particularly well at this

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Jim Watts
http://jameswattsguitars.com

I'm wondering how was this problem dealt with in the past.  150 years ago, or only 50 for that matter.  When has AC become a widespread affordable commodity ?  

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Build log

Torres, for instance, is said to have burned the midnight oil and done a lot of assembly at night when the humidity levels were right. They used to use thin pieces of spruce mounted at one end that would move with the changing humidity, when it was right they did their assembly.

Their top wood was also kept under open sided covers on their roofs under the Spanish sun where it would go through the baking and cooling day after day until an incredible stability had been reached. Many builders now are baking their tops to try and achieve the same thing.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Oh, my work shop is not climate controlled ina any way, it's in a very old building and this would not be practical. My wood store in the house is a spare 3m x 3m rom that does have a small dehumidifier in. wood or guitar parts are stored their and just taken to the shop to be worked on, then returned to the store. The small amount of time they are out of the controlled environment is not enough to have any effect. Like the cupboards mentioned in the posts above.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

[QUOTE=AlexM] I'm wondering how was this problem dealt with in the
past.  150 years ago, or only 50 for that matter.  When has AC become a
widespread affordable commodity ?  
[/QUOTE]

The way I have built in the past and probably always will, is by building
with the wood extremely dry and designing around that. Bracing
intentionally dried wood, then allowing it to expand in to a healthy radius
is an old and reliable method.

For example, if I want a 16" top to be at a 20'-25" radius at 50% humidity
then I will "bake" it at about 120 degrees with good convection for about
an hour. Even if the humidity is high, in Michigan weather this will put the
oven fairly consistently at around 15% humidity in my shop, and within an
hour of good air flow over a piece of spruce it will bring the moisture
content down to near 4%. Then by immediately bracing the top in to a
shallow radius (let's say 60'), when it returns to 50% and the wood comes
back to the 6% range of moisture content the soundboard will swell over
the braces to around a 25' radius.

This method builds a good deal of internal stresses in to a top and back,
not unlike the "sprung" braces commonly used by classical builders (over
radiusing the braces and gluing them up on a flatter surface), and
certainly has effects on tone that I haven't really heard by other means.
Steinway has been doing this process to achieve the crown of their
soundboards for well over a hundred years, and I'm sure it's been used
long before that.

It certainly takes some experimentation on part of the builder to find the
range and process that works consistently for them, but it certainly
provides some degree of a constant in building. There are enough
nuances to this procedure that it would certainly take a good lengthy
discussion to get the details out there. This manipulation can take place
with the top and back at many points - before joining, then before
bracing, and the timing of gluing the top and back to the sides can be
important.

Unfortunately, I'm going to leave you with that to chew on and step away
for a while. I'm turning this computer off and heading up to lake Superior
in about 20 minutes. No internet, no cell phones, aaahhhhh.........

I'll be back in a week or so. Maybe. Have fun folks.

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Eschew obfuscation, espouse elucidation.

Ok that is somthing to chew on indeed....


Anyway, the good news is that is it looking fairly good now.

Today is has rained for almost the entire day. I left the top close to the open window for a couple hours and that fixed it.

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Build log