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| Author: | fingerstyle1978 [ Tue Nov 16, 2010 6:47 pm ] |
| Post subject: | Bracing mistake |
I cut the upper bout brace into the dimensions prescribed in Cumpiano's book. However the brace does not reach all the way to the sides. How big a deal is that? Seems that brace is designed to take a bit of the load from the string tension. Also how important is it that the finger braces and the braces below the bridge actually touch the X Brace? A bracing pattern I have shows none of them touching, which seems a bit strange from what I have seen from everyone else's work here. thanks |
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| Author: | Rod True [ Tue Nov 16, 2010 6:50 pm ] |
| Post subject: | Re: Bracing mistake |
You definatly want to tuck the UFB into the linings. As for the lower braces, Most people tuck the X-Brace legs into the linings but everything else is just tapered to nothing, just before the liners. And by nothing, we are really talking about the glue line here 
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| Author: | SteveCourtright [ Tue Nov 16, 2010 7:06 pm ] |
| Post subject: | Re: Bracing mistake |
I agree with Rod on both counts. |
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| Author: | DennisK [ Tue Nov 16, 2010 7:31 pm ] |
| Post subject: | Re: Bracing mistake |
Yeah, cut a new UTB, chisel the old one off if you glued it already. Not enough wood to compromise on. Although being that my guitar is meant to be functionally a Gibson Hummingbird clone, I was examining the bracing inside one at a store, and oddly enough the UTB was tapered to nothing at the linings  Not that Gibson is necessarily a good example to copy. I left it about 1/4" and tentelloned my way over it.As for braces touching the X... it can go either way. I did fingers tapered to nothing at both linings and X, tone bars tapered to nothing at linings, other end scalloped down to about 1/8" or a bit less and butted to the X. As I understand it, the thinner you go on the top, the stronger you need the brace connection points to make up the stiffness. But it entirely depends on what you're trying to do. Stronger connections means the top moves more as a unit and favors low frequencies (especially if it's loose around the perimeter), weaker connections let the braces move individually and favor high frequencies. See Somogyi books for better explanation. |
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| Author: | fingerstyle1978 [ Tue Nov 16, 2010 7:41 pm ] |
| Post subject: | Re: Bracing mistake |
thanks guys, I suppose I better take the utb brace off  and cut another. Lesson learned. I shouldn't have tried to be cheap by avoiding cutting another piece of spruce bracing, which is relatively cheap anyways. Live and learn.
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| Author: | Tom West [ Tue Nov 16, 2010 8:10 pm ] |
| Post subject: | Re: Bracing mistake |
Joey: The utb needs to be let into the lining as does the X brace in the upper bout. Forces here are trying to pull the braces away from the top. On the lower bout not so important because the braces are being pulled into the top. Some folks even taper the lower ends of the X brace to nothing depending on how loose you are trying to go. I inlet at the bottom X and think most folks do. I never inlet the fingers and sometimes not the tone bars. By the way, lots of brace stock at most local lumber yards if you look hard. Tom |
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| Author: | jfmckenna [ Wed Nov 17, 2010 10:27 am ] |
| Post subject: | Re: Bracing mistake |
I thought that I learned on this forum that it's a good idea to have a little space on all the braces that tuck into the lining from the sides themselves? That way with shrinkage and swelling you won't have brace ends poking on your sides/binding if they have a bit of breathing room. So If your brace is able to tuck into the lining but is not actually butted up against the sides then from what I came to understand that is desirable. IF your bracing doesn't even reach the linings then you will need to replace it. FWIW I don't butt or notch finger braces or lower cross braces to the X brace, in my guitars they are free floating. |
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| Author: | jeb98 [ Wed Nov 17, 2010 1:35 pm ] |
| Post subject: | Re: Bracing mistake |
I had the same problem on my first build, and it was very difficult for me to get the proper fit. I have decided that on my second build I will glue the top onto the rim before I glue the back on. This way I can see from the inside exactly what is going on and it will be easier to glue in shiims into the kerfing notches if I need to, or to see how far I need to cut the kerfings. It seems like most people glue the back onto the rims first, so is there any specific reason why I should glue the back on first? Thanks, Jonas |
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