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| bracing design question http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=51197 |
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| Author: | phavriluk [ Tue Nov 06, 2018 4:10 pm ] |
| Post subject: | bracing design question |
I'm drawing the top bracing of my next scratchbuilt project - - - outline from a Martin Herringbone at 93% of the original size, with a short-scale (24.82") neck joining the body at the 12th fret. Implied in this layout is a bridge moved closer to the end block. My question involves where to put the 'x' brace and how wide do I spread the legs? (I've built two earlier versions of this body with a 14-fret neck and the first sounds wonderful to me and the second is being finished.) But I can't copy (or can I?) the bracing geometry of the first one. I need to accommodate supporting the bridge with the 'x'. I think I have two choices: (1) move the existing bracing design farther down the body, which I think in builders' terms it means rear-shifting the 'x' brace or (2) keep the 'x' brace just south of the sound hole (forward shifted?) and close up the angle of the 'x' so that the bridge sits at the same position on the 'x' as the 14-fret version. Damfino what ought to be done and what acoustic implications accompany my choices. Suggestions and comments, folks, please? Thanks very much. |
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| Author: | Haans [ Tue Nov 06, 2018 4:35 pm ] |
| Post subject: | Re: bracing design question |
I have spread X's out probably farther than anyone. As long as the X crosses the bridge in the proper fashion, you will be OK.  These are the best sounding Grand Concert bracings I have ever done. X crosses midway between the saddle and back of sound hole. Live a little...experiment. |
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| Author: | Bryan Bear [ Tue Nov 06, 2018 5:05 pm ] |
| Post subject: | Re: bracing design question |
I just did a very small body guitar where I had to make similar decisions. 12 fret neck on a shorter body. I ended up keeping the x juncture fairly far from the bridge making sure the bridge caught the arms of the X. I tried to maximize the x angle without having it too close to the bridgeplate. It was very much by my gut. Then I placed the angle of the tonebar by eye thinking about having just enough (but not too much) cross grain stiffness. In the end, it turned out well. |
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| Author: | DennisK [ Tue Nov 06, 2018 6:39 pm ] |
| Post subject: | Re: bracing design question |
Haans wrote: I have spread X's out probably farther than anyone. As long as the X crosses the bridge in the proper fashion, you will be OK. These are the best sounding Grand Concert bracings I have ever done. X crosses midway between the saddle and back of sound hole. Live a little...experiment. Don't forget to show your carbon fiber tubes in the box as well  I wouldn't recommend using such light upper bout bracing without them.Without the tubes or other buttress system, if the upper legs of the X are very far from the upper transverse brace, the soundhole braces should be beefed up a lot to prevent the box from folding up there. But I generally use a more elongated X on 12 fret guitars to get the upper legs close to the upper transverse brace. You can also use a wider bridge to allow for more X spread, while still having good overlap. |
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| Author: | Haans [ Wed Nov 07, 2018 8:51 am ] |
| Post subject: | Re: bracing design question |
UTB is maple and the doubler keeps the sound hole from folding, but yes, there are CF tubes... 
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| Author: | bcombs510 [ Wed Nov 07, 2018 9:22 am ] |
| Post subject: | Re: bracing design question |
That is a fascinating design. I often hear the guitar wants to "fold itself in half". That ain't happening!
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