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I am building a small bodied classical based on a Torres FE17 size, shape, and general bracing, but not a copy. The guitar is for a friend of mine, who lives in Arizona and, depite being well aware of the effects of low humidity on guitars, refuses to keep a guitar in a case. She does at least keep Oasis type humidifiers in the soundholes, and they are inserted through a hole in a soft neoprene soundhole cover. My question is: Do bridge pads add any structural strength? I was not planning on using one, since Torres does not, but any help I can provide to keep the guitar from cracking I would be willing to do. I have also read somewhere in the archives that a cross brace under the bridge can add some structural strength and help to maintain the arch. I am a little concerned with overbracing, since this is a very stiff bear claw Sitka top. Even at a hair over 2mm it still feels quite stiff. I have been keeping the humidity down lower than usual in my shop, and hope to assemble at somewhere between 30-40%. But humidity here can dip much lower than that. Please do not suggest trying to convince her to use a case, since that is a done deal and she is willing to take the risk. So any suggestions as to bridge pad, crossbrace, or nothing as planned?
Thanks, Wendy

Even some modern flamenco guitars (such as Reyes - see GAL plan) have quite long bridge patches spanning quite a wide portion of the soundboard (from side to side), and this does not appear to be detrimental. The Reyes has a relatively large soundboard, though, and might be quite floppy when thinned to flamenco thicknesses without the bridge patch. I'm not sure of the pros and cons on the Torres design, but I guess I'd be inclined to add the patch given what you know about the guitar's living conditions.

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Jim Kirby
kirby@udel.edu

I'm just going to mention this. I have read that a bridge patch could actually work against you as an insurance against cracking. When you glue a Spruce patch cross grain to a Spruce top, you are gluing a patch that does not expand and contract much longitudinally with a top that expands and contracts a great deal across the grain. The patch could actually introduce a cracking hazard, when the patch and the top are working against each other.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

It is certainly true that crossgrain is a problem, but the bridge is also crossgrain, so the question is whether the patch will help sort out a problem that is already there. Like 3 layer plywood rather than just the first two layers. I'm no help, it isn't all that tough on wood around here. I would start with a domed soundboard in the area of the bridge.

The thing I don't understand about the bridge patches I see used on classical guitars is that they don't seem to be any wider (from front to back) than bridges. In that regard I don't see how they help at all in preventing the bridge from pushing the sound board down in front and up below. I will say that if the patch is made a little wider than the bridge and is nicely rounded on the ends, it could assist in preventing cracks coming off the sharp corners of the bridge which are local stress points.

Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

I had decided to not use the bridge patch, and this morning I am getting ready to start bracing and am having 2nd thoughts again. I'm confused after reading Tom's reply to what Waddy said, since it's true that the bridge is also crossgrain. Any more thoughts on this? The only thing I have to go on is 2 guitars that have hung exposed on the wall at a friends house, both classicals about 35 years old. 1 is a Hirade, and the other is a Yairi. The one with the soundboard cracks is the Yairi, built without a bridge patch. It's not really a good example, I know, since the Yairi has been treated poorly, and neither is a high end guitar. Not to mention all the other variables like soundboard thickness and bracing. It just got me wondering. Wendy

You're going to build a guitar based on one from the greatest guitar maker of all time, many have tried to improve on them, none have convincingly succeeded. Many of his guitars still survive and not one ever had a bridge patch. I build pure Torres, and have never felt the need for one either. Don't overthink this, or try and second guess the master. You don't need a patch.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Thanks for that post, Colin! It should be in the post hall of fame (if there is one).

I thrashed around on the bridge patch concept for years, and ultimately dropped it for numerous reasons. Hauser haunts us with it. As far as I'm aware, Hauser was the first to use it on a classical guitar - my guess is that it was a vestige from his northern European style guitars, but that's just a guess as I'm not aware of any Spanish luthier having used it before Hauser. 1937 was the period when he was still trying to please Segovia and did a lot of experimenting. It's important to note that later Hauser guitars (at least some) did not use the bridge patch.

Happy Holidays, all!

In my opinion, the important point here is that you keep the humidity way down when building this instrument.

Thankyou Colin and Bart, exactly the reason I had decided not to include it, and then you are right, I started overthinking it when I got worried about the conditions it would be kept in. And keeping the humidity way down is the plan, wouldn't you know that the weather has changed and I may have to put it on hold for a while. My dehumidifier is running full blast and the shop doesn't want to drop below 48%. I'm thinking of heating it very high and then kicking on the a/c to dry it out. Last time I did that I froze up the a/c, but it's not that cold out this time. I usually don't assemble in the winter here because this is when we get our rain. Thanks for the advice and I'll let this discussion rest now.