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Bridge wings and overlap with X brace
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=47926		 Page 1 of 1
Author:  tjp [ Wed Jun 22, 2016 11:47 am ]
Post subject:  Bridge wings and overlap with X brace
Laying out the bracing on #9 and pondering where the bridge sits on the X. The previous few guitars, I've run the X under the back corners of the bridge wings with good success. This one, I think the X will go under the front half of the bridge wings, leaving the back "free". In theory, this seems like it would directly under the front half of a bridge that is trying to rotate forward, while maybe leaving the area behind the bridge a little more freedom to move. I also like the fact that it allowed me to open the X to 97 degrees, with the intersection about an inch behind the soundhole. Looking at some of the photos in the Martin bracing library, this seems fairly similar to what they did in the prewar era, and maybe the direction they are headed nowadays.

Any opinions? Plusses/minuses?
Author:  kencierp [ Wed Jun 22, 2016 12:19 pm ]
Post subject:  Re: Bridge wings and overlap with X brace
Seems we are pretty much free to do what we want -- you've got ladder braces patterns, fan brace patterns, wide "X" narrow "X", huge bridge plate small bridge plates. Point being with some patterns there are no "X" legs to sit on at all. For a long time I was under the impression that the bridge wings should always sit on top the X legs. But then Preston Thompson sent me a shadowed brace pattern of an authentic vintage "D" size Ditson -- with that pattern a standard 6" bridge just barely brushes the LB legs. The guitars I've heard made for that (KMG) template sound really very nice, well balanced and very loud.
Author:  powdrell [ Wed Jun 22, 2016 1:23 pm ]
Post subject:  Re: Bridge wings and overlap with X brace
tjp; I cross 'em at front corner of wings for the reason you mentioned....
Author:  Woodie G [ Wed Jun 22, 2016 1:30 pm ]
Post subject:  Re: Bridge wings and overlap with X brace
We don't have a hard-and-fast rule, but the 12 fret and the smaller-bodied guitars tend to have less overlap than larger 14 fret guitars like the dreadnought or jumbo. A Size 2 or Size 5, or our version of the Normal Blake in 00 and 000 sizes have the least overlap (the rear of the X is about 1/2" behind the front edge of the bridge). For a 14 fret dreadnought, the back corners of the bridge wings just touch the X braces, and for the 12 fret dreadnought, are about a 1/4" shy of touching the X.
Author:  Terence Kennedy [ Wed Jun 22, 2016 11:22 pm ]
Post subject:  Re: Bridge wings and overlap with X brace
I like to see at least one set of corners overlap the X. Any data other than anecdotal to support that as far as long term structural issues? Not that I know of but it makes sense to me.

I splay the X on my size 2's a little more than the plans and simply lengthen the bridge wings a little so at least the top corners overlap. Bridge is around 6.5" long and they sound fine.
Author:  Tom West [ Thu Jun 23, 2016 8:33 am ]
Post subject:  Re: Bridge wings and overlap with X brace
I tend to follow Somogyi in the belief that the monopole is the most important mode. This is said to work best when the top moves as a whole, this happens the best when the X brace is well coupled to the bridge. To this end I like the bottom corner of the bridge to at least meet the inside edge of the X. I also follow Ervin's hint to not thin the bridge wings too much and not have the bridge vibrating by itself. That being said there are lots of ways to make these creatures work and lots of examples of that happening.
Tom
Author:  DennisK [ Thu Jun 23, 2016 8:47 am ]
Post subject:  Re: Bridge wings and overlap with X brace
Tom West wrote:
I tend to follow Somogyi in the belief that the monopole is the most important mode. This is said to work best when the top moves as a whole, this happens the best when the X brace is well coupled to the bridge. To this end I like the bottom corner of the bridge to at least meet the inside edge of the X. I also follow Ervin's hint to not thin the bridge wings too much and not have the bridge vibrating by itself. That being said there are lots of ways to make these creatures work and lots of examples of that happening.
Tom

Exactly. The highly coupled design is theoretically superior (especially for small guitars, IMO), but that doesn't mean the tone it produces is everyone's exact taste. There are countless variations on soundboard design that function plenty well, and sound different and interesting in their own way. Build it and see if you like it :)
Author:  tjp [ Thu Jun 23, 2016 10:49 am ]
Post subject:  Re: Bridge wings and overlap with X brace
Yeah, I've been staring at it and thinking about it and I like the pattern. I like the idea of slightly thicker bridge wings. The center point of the wings will intersect with the bridge plate side of the brace. It'll be a 25 inch scale, J45 pattern, 97 degree splay, 1 inch behind soundhole, .070 X 1.75 inch Jatoba bridge plate (slightly wider than normal to help compensate for a thinner top), .110 ultrastiff sitka top from Alaska specialty woods. Otterhound's beautiful Walnut B&S, a set I have been saving for myself, back will be about .090. I love all the individual pieces of this one, can't wait to see how it all comes together. Will build and report back.

Just a FYI, a couple of years ago I ordered a box of 12 tops, AA to low AAA from Alaska Specialty Woods for a smoking deal. Many of them are kind of ugly as raw plates, maybe a knot outside the pattern, ragged edges, not the kind of sets that you could sell for top dollar. 5 of these sets were tonally something special, you could tell just by brushing your hand across them. I think from the same tree. I want some more of those.... Anyway, point being it would be worth your time to see if this offer still exists, and Brent could use the support after his recent troubles.

Doug! Thanks for checking in, good to hear you are still building...
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