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| preshaped braces or laminated curve? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=29862 |
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| Author: | chinito [ Wed Nov 10, 2010 4:45 pm ] |
| Post subject: | preshaped braces or laminated curve? |
I started bracing my first flamenco top yesterday. I'm fascinated by the tension/tension free building debate, and I'd like to know what methods forum members prefer. In this case I was wondering about the fan struts and doming of the lower bout. Arching fan struts before gluing vs. straight fans glued into an arch using clamping pressure (laminated curve). I'm pretty much set on the latter approach based on Eugene Clark's AL article. Still interested in hearing pros and cons of either approach tho. Thanks, -J. |
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| Author: | chinito [ Fri Nov 12, 2010 2:03 am ] |
| Post subject: | Re: preshaped braces or laminated curve? |
Is this a noob question to be even asking? Anybody? -J. |
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| Author: | Kent Chasson [ Fri Nov 12, 2010 2:24 am ] |
| Post subject: | Re: preshaped braces or laminated curve? |
Assuming you are talking about a typical amount of dome and typical fan braces, not something extreme, here's what I know (which isn't much). Bending them does add a bit of stiffness, at least in the short term. I wouldn't be surprised if that effect diminishes over time as the wood relaxes into the curve. I have heard people claim that bending braces can lead to the braces telegraphing through the top and showing up as a slight depression at each brace. I can't speak to that first hand though. It's also a bit harder to control the dome as it will spring back a bit. |
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| Author: | Alexandru Marian [ Fri Nov 12, 2010 3:11 am ] |
| Post subject: | Re: preshaped braces or laminated curve? |
I think most builders following the traditional methods and press them in. Fan braces are small and some go at great lengths to unsure there is no runout in them. Why then cut through it? As Kent said they surely adjusts into the new shape quite rapidly. Just take a small brace and force it in your hands over its elastic limits, but don't break it. It will remain bent. Same happens within the elasticity limits under a long and steady pressure. Fact is that this method creates a very nice and healthy doming which can keep its shape well. I've seen plenty of flat built guitars which in less than a couple years had a pronounced dish. My first guitar has zero distorsion even after 3 years and the top is a mere 1.9mm of very light spruce between sound hole and bridge, with regular Torres braces nothing overly stiff. If you want to reduce telegraphing, I think hideglue and dense tops have it less than a light (even if thicker) top made with fish or white glue. |
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| Author: | chinito [ Mon Nov 15, 2010 12:14 pm ] |
| Post subject: | Re: preshaped braces or laminated curve? |
Thanks for the responses guys! Kent: I have a bit of extra material removed from my solera to account for springback if I glue flat braces into a curve, but it is still an ok amount of doming for precurved bracing also. The telegraphing through the top you mentioned is one of my bigger concerns with sprung bracing. My top is cedar and fairly stiff, but deforming is something I'd obviously want to avoid. Alexandru: I've got a mix of split and sawn spruce for my bracing. The split material is for the fans. When you mentioned flat built guitars am I correct that this refers to flat braces glued into the curve? I'm not experienced enough at this point to know what constitutes lite or heavy bracing, but my plans call for fans that are on average close to 1/8 of an inch tall by 1/4 wide. I will be using Titebond to glue them in. Thanks, -J. |
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| Author: | Alexandru Marian [ Mon Nov 15, 2010 12:27 pm ] |
| Post subject: | Re: preshaped braces or laminated curve? |
By flat I mean flat flat no curve! |
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| Author: | chinito [ Mon Nov 15, 2010 12:42 pm ] |
| Post subject: | Re: preshaped braces or laminated curve? |
Alexandru: Ok. I think I know what you mean. Flat tops domed by string tension pulling the lower bout up at the bridge? I can see how that would work to counter act any springback after gluing the braces. Smart. -J. |
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| Author: | Alexandru Marian [ Mon Nov 15, 2010 12:58 pm ] |
| Post subject: | Re: preshaped braces or laminated curve? |
Well in all cases there is some pull up from the strings. You should not worry that much about bracing springback. |
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