OMG, he used flamed maple...
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| Upper transverse brace height http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=50325 |
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| Author: | talladam [ Mon Feb 19, 2018 1:57 pm ] |
| Post subject: | Upper transverse brace height |
Hi! I am building an OM from the Kinkead book. He calls for an upper transverse brace 13/16" tall. The brace stock I received is 3/4" thick, so by the time I work with it, it'll be 5/8-11/16" tall. Should I find a bit more brace stock (probably can get some in town here), or do you think I am tall enough? |
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| Author: | AndyB [ Mon Feb 19, 2018 2:04 pm ] |
| Post subject: | Re: Upper transverse brace height |
You are probably fine if the UTB material is vertical grain and suitably stiff. Just don't whittle it to nothing. Then again, no lack of spruce where you live ... Andy |
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| Author: | meddlingfool [ Mon Feb 19, 2018 2:06 pm ] |
| Post subject: | Re: Upper transverse brace height |
That's fine. |
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| Author: | Colin North [ Mon Feb 19, 2018 2:36 pm ] |
| Post subject: | Re: Upper transverse brace height |
For that plan I've taken the UTB down to 7/16 wide x 5/8 high with no apparent problem. Just make sure it's good stiff spruce with vertical grain. |
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| Author: | talladam [ Mon Feb 19, 2018 3:26 pm ] |
| Post subject: | Re: Upper transverse brace height |
It is nice spruce. Dead on quartered. I can even see some really nice silking (it's probably a cutoff from a nice top billet). Did you build a Kinkead OM, Colin? I wonder if you found it a bit overbuilt? |
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| Author: | Joe Beaver [ Mon Feb 19, 2018 3:42 pm ] |
| Post subject: | Re: Upper transverse brace height |
I'm not familiar with the Kinkead plan, but my only concern is if you are planning a thru the soundhole truss rod adjustment, and the Upper transverse brace is what I call an upper face brace. Just make sure you have room to drill a hole through the brace for the allen wrench |
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| Author: | Colin North [ Mon Feb 19, 2018 3:49 pm ] |
| Post subject: | Re: Upper transverse brace height |
talladam wrote: It is nice spruce. Dead on quartered. I can even see some really nice silking (it's probably a cutoff from a nice top billet). Did you build a Kinkead OM, Colin? I wonder if you found it a bit overbuilt? I've built 6 now I think, and yes, the plans are overbraced, as I found out with my first. |
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| Author: | talladam [ Mon Feb 19, 2018 5:48 pm ] |
| Post subject: | Re: Upper transverse brace height |
Yes, Joe, I will be drilling a hole in it. maybe 5/16"? |
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| Author: | talladam [ Mon Feb 19, 2018 5:51 pm ] |
| Post subject: | Re: Upper transverse brace height |
Colin, Do you mind giving me an idea of what you do to lighten up the bracing? |
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| Author: | Woodie G [ Mon Feb 19, 2018 7:21 pm ] |
| Post subject: | Re: Upper transverse brace height |
13/16" seems excessive, unless the brace is quite thin (0.250" or less) and tapered. The UTBs on a range of quality instruments I've worked on in the 000/OM size range are usually 0.575"-0.650" x 0.375" - 0.500". The usual UTB size for an OM here is 0.575" x 0.375" per the shop's Builder's Guide. We use a 0.250" truss rod access hole spaced 0.063" in from the soundboard edge of the brace, as necessary to accommodate a 5mm truss rod wrench. |
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| Author: | Joe Beaver [ Mon Feb 19, 2018 9:53 pm ] |
| Post subject: | Re: Upper transverse brace height |
It sounds like you radius your upper brace. I leave mine flat since i want a flat area for the fingerboard extension. Some arch should be fine as long as you flatten the area under the extension. Either way your material should be fine. I drill a 1/4" hole. All you need is room for the allen wrench. I use two styles of double action truss rods, Blanchard and Martin. For the Blanchard rod I drill the access hole (center line) 1/4" below the soundboard, and 5/16" for the Martin. I use a 5/16" wide x 5/8" tall upper transverse brace for the Blanchard and 1/16" taller for the Martin. I do put my truss rods in flush with the top of the Neck, no filler strip. Blanchard does recommend a filler. If you do use one with whatever brand rod, I'd move the access hole down accordingly to keep the hole and rod lined up. |
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| Author: | talladam [ Mon Feb 19, 2018 10:33 pm ] |
| Post subject: | Re: Upper transverse brace height |
I'm not planning on radiusing the brace. It'll just shrink a bit because it is really rough and splintery so I'll have to plane a smooth surface on it. Thanks to all of you for your help. It's amazing the information you can get here. |
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| Author: | Woodie G [ Tue Feb 20, 2018 6:10 am ] |
| Post subject: | Re: Upper transverse brace height |
Joe Beaver wrote: It sounds like you radius your upper brace. I leave mine flat since i want a flat area for the fingerboard extension. We actually radius to 60', which generates a sagitta of 0.0015" through the width of the fretboard extension (with that UTB glued onto the top with flat caul), but properly sets up the extension for 28' radius lower bout bracing. With the sagitta for the entire UTB span of 11.5" (standard Martin 000/OM upper bout width at the UTB) at about 0.020", this also provides some protection against the concave upper bouts sometimes seen on instruments. What I think would be of interest is methodology that would generate an optimum fit for the extension, correct neck angle, and provide some natural resistance to concavity in the upper bout over time - all without excessive thinning or modification of the contour of the upper bout after the box is closed...this is why I persist in the line of questioning. The approach used here works for every guitar I have seen strung up (i.e., 60' UTB glued flat; 28' X, tone bars, face, and bridge plate in 28' radius dish), but it seems like the wedge method SHOULD be more consistent, provided the precise angle can be set and milled. |
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| Author: | Colin North [ Tue Feb 20, 2018 7:57 am ] |
| Post subject: | Re: Upper transverse brace height |
talladam wrote: Colin, Do you mind giving me an idea of what you do to lighten up the bracing? PM sent |
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| Author: | Haans [ Tue Feb 20, 2018 10:44 am ] |
| Post subject: | Re: Upper transverse brace height |
OMG, he used flamed maple...
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