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| Few questions about classical bracings http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=26231 |
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| Author: | Matt Shumway [ Wed Feb 24, 2010 2:54 pm ] |
| Post subject: | Few questions about classical bracings |
two questions. 1. Is it super duper important for the bracing to butt up right against the sides? Its my first guitar ever and one of the top braces isnt quite long enough to reach the sides. If its really critical, I suppose I could add some wood to the ends right? 2. I am following the 1969 Robert Bouchet plan, and it calls for some bracings on the sides. It mentions that they are aligned with the back bars and harmonic bars. What are those? Basically, where should I put em along the sides? In addition, im not sure if I should make them out of mahogany or some scrap spruce I have from the top. Which do you think is best? thanks! |
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| Author: | WaddyThomson [ Wed Feb 24, 2010 5:48 pm ] |
| Post subject: | Re: Few questions about classical bracings |
Hard to answer your question as stated. I don't know the Bouchet plan, but are the braces scooped at the ends? If so, will they make it under the edges of the linings? You wouldn't want to have a gap between the brace and the linings, where the top is unsupported. It could create a stress point that might cause a crack between the brace and the linings. If the brace makes it under the edge of the linings, then you should be OK. Just notch the lining just enough for the amount of brace underneath. If the braces are full height at the lining put a block on top of the brace and glued to the side to fill the gap. Some builders make the braces slightly short of the sides to allow for expansion. The Transverse braces on the top and the back braces are the back bars and Harmonic bars that are mentioned in the plan. If they are aligned, you can just put a strip of mahogany or spruce or what ever is suggested between the top and back bars, with vertical grain, across the grain of the sides. If these are wider at the top and bottom, and thinner in the center, you can use these to cap the braces, top and bottom. My braces are full height at the sides, and I put blocks to support them. Here is a picture of how I do it. Attachment: P1030167 (Large).JPG This is before the back braces are glued in, but you can see the supports. |
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| Author: | Matt Shumway [ Wed Feb 24, 2010 6:09 pm ] |
| Post subject: | Re: Few questions about classical bracings |
Thank you that does help some. Yeah one of my top braces (the one across the lower bout) isnt even reaching the binding, and they are scooped at the ends, I left about 1/4 inch high at the ends. So I guess I should put a bit of extra wood in there, enough to go under the binding? Bouchet may have done the back braces in the exact same spots as the top braces and had everything lining up. But there is nothing in the plans that really told me that (at least that I can see) so I followed Cumpiano's measurements for the back braces. They are close, but not quite the same as the top braces. So do you think it would be all right to put the side braces lined up with either the back or the top braces? Or split the difference? |
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| Author: | WaddyThomson [ Wed Feb 24, 2010 6:15 pm ] |
| Post subject: | Re: Few questions about classical bracings |
Either, I think, but make sure you let them into the linings. Don't let them float free on the sides. What are you using for linings? I still don't get the picture on the top brace that's short. How short in inches or mm from the actual side? Have you put the linings on the sides yet? |
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| Author: | Matt Shumway [ Wed Feb 24, 2010 6:40 pm ] |
| Post subject: | Re: Few questions about classical bracings |
here is a photo.   This is before the linings, ive glued the the top ones into the sides already. Haven't glued the sides down to the top yet though. With the linings in, this brace is not quite or just barely touching the linings. m using kerfed linings |
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| Author: | WaddyThomson [ Wed Feb 24, 2010 11:12 pm ] |
| Post subject: | Re: Few questions about classical bracings |
It looks like you'll be fine. You might want to carve it down so it's flat going under the linings., so when you notch them you can make a square, flat bottomed notch. |
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| Author: | Matt Shumway [ Wed Feb 24, 2010 11:46 pm ] |
| Post subject: | Re: Few questions about classical bracings |
Here are some shots with the binding:  Close-up:  So should I extend the brace with a bit of extra wood? And thanks for the help Waddy, you should visit my build thread every once in a while over at Luthiercom.org. wink wink nudge nudge http://www.luthiercom.org/phpBB3/viewto ... =41&t=1558 |
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| Author: | Jeff Highland [ Thu Feb 25, 2010 12:40 am ] |
| Post subject: | Re: Few questions about classical bracings |
No expert, but from my reading of the text of the courtnall book, the bridge bar (the crossbar under the bridge location) should finish before it reaches the linings so you are fine there. |
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| Author: | WaddyThomson [ Thu Feb 25, 2010 11:17 am ] |
| Post subject: | Re: Few questions about classical bracings |
Good catch! I think you are right. I didn't notice that it was the bridge bar, and not a brace. I guess I'm just not used to that, as I don't use one or even a bridge plate on my guitars. I don't think that bar needs to go under the linings at all, but should be feathered to nearly nothing at the ends. "Linings" are inside the guitar, "bindings" are on the outside, at the edges. |
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| Author: | Matt Shumway [ Thu Feb 25, 2010 6:35 pm ] |
| Post subject: | Re: Few questions about classical bracings |
Ahh yeah mixed up the words heh, guess that could throw you off a bit. rookie mistake!! |
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