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Top sinking aross waist? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=4183	Page 1 of 1

Author:	John B [ Tue Dec 20, 2005 8:11 am ]
Post subject:
The other night I happened to view my guitar in just the right light - just the right light to notice that it appears the top is sinking right across the upper part of the waist I can see a distinct line where the kerfing extends from the sides. My first thought is that it might be a humidity issue. We've had a sudden drop in humidity recently, so I fired up a humidifier in the room - hoping that will take care of the problem. The second thought is that it might be a bracing issue. I built the guitar as part of Harry Fleishman's class. He uses a cylindrical top, rather than a spherical top. In the class I decided to get a little experimental - the cylindrical radius is 25' on the bass bout, 12.5' on the treble bout. I was aiming for a more archtop-like treble attack, with a flattop response in the bass strings. I was fairly aggressive in shaping my braces; however, I don't believe I did anything to the top of the X brace. The cross brace right above the soundhole is also a fairly hefty brace. The soundhole is somewhat larger than what Harry usually builds - it's at least 4", and the brace right above the soundhole is immediately above the soundhole. Maybe some combiniation of the compound radius, larger soundhole, and light bracing elsewhere is contributing to this sink? I'd appreciate any thoughts - I'm thinking that low humidity is the primary culprit, though.

Author:	John How [ Tue Dec 20, 2005 8:39 am ]
Post subject:
If it chaanged after you glued it up, it's no doubt humidity. Just be patient. Hopefully the humidity was right when you glued it and will come back to that state.

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