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Today I cut seventy five sets of main xbraces out of aged Sitka. I ripped and ripped and ripped. Then I sanded sanded sanded to 5/16ths of an inch. These babies are fine.

I put fifty sets on the shelf taped up in bundles of 25 pairs. By the time I got to the last set, I drug my stool over to the card table catching the braces as they came out the sander, I was tired. Just sat there kind of out of gas, looking at a helter-skelter pile of braces.

As I stacked them up, I flexed a few, and what I discovered caught my attention. Most of the braces were very strong, well quartered, little to no runout. But some were very flexible in comparison to the others. Eureka!

So, all good wood, but some are gooder than others. I can imagine the really flexible braces sucking up sound. Also, the term rubbery comes to my thinking on the less desirable braces. Well that's it, I'll post again on this subject after building a few dozen guitars with this Sitka.

A friend of mine worked for a well-known luthier, and they flexed bunches of pre-carved brace stock looking for the stiffest ones, and matching the pieces up together to get the best X's. But they used red spruce exclusively.

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I believe there was an article by Al Carruth in an issue of American Lutherie regarding brace stiffness, which detailed a useful and simple deflection jig for testing the stiffness. I threw one together that is similar and use it to decide which order to put my fan braces in. Just requires a dial indicator, a clamp used as a weight, and a wooden base to secure the end of the brace that is not weighted down.

Come to think of it. I really need to re-make mine to be a bit more user friendly.

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Good grief Bruce 75 braces? Well I guess you won't need to repeat that task for awhile anyways.
      I've noticed differences in brace stiffness for a while. Sometimes I have to out right reject some top braces, particularly x-braces. I usually try to select the best brace stock for top bracing. I make maybe 3 or 4 sets at a time and try to match em up stiffness wise.
Of course I spend WAY to much time flexing braces and tops, don't know if I've learned anything yet but I do it anyways. Kinda makes me feel luthier like<bg>.
      

I measure the deflection on all of my braces and group accordingly. You would be surprised that some braces are equally stiff in both directions while others are stiffer in only one direction and very weak in the opposite direction. Some braces make excellent kindling too.

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tim...
http://www.mcknightguitars.com

Well after all that I would have grabbed a beer, a stool ,and my ole L-00 sat back and played
"Those Old Bruce Spruce Blues"
or was it "Those Old Blue Spruce Blues" or was it???????   
Oh hell I'm going to get a beer anyhow Bobc38405.8820949074

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Paul, that's seventyfive times two, 150 main braces, but seventyfive sets. That's why I learned what I learned.

Now I'm headed back down and gonna cut twenty five sets of Adirondack so I can do a blindfold test, and AB Addy and Aged Sitka. Nothing like quality over quantity. But nothing like quantity to tell if you have quality.

Just thinking back to my first guitar. I don't have a clue whether those were good braces, I just glued them on without questioning. Which leads to the answer to a recent query, "Why is a hand-made guitar any better than a factory-made guitar?" The answer is that I will take the time to determine every aspect of each guitar, to the best of my ability. While I'm sure all these braces will make a guitar. I'm also sure that some braces are better than others, and we are talking the main braces of the sound producing structure.

Yes Paul, you are right, I won't have to repeat this task, like you said. I was attempting to rid myself of the pile of old spruce door panels, I only cut up ten or so. Looks like I need to have a garage sale in the old garage.

Bob, I'd grab my guitar and play that tune, but remember, I don't know how.

Don W. Addy sounds like Bourgeois. I too use only Addy, but this find of old Sitka may change that. I kept splitting away in the garage until I was convinced that the majority was good and had little runout. I did find some early that had major runout, almost made me stop in my tracks. Glad I didn't.

You've got me thinking about them blocks 'o' Italian I've got for bracing stock here. Have 8 right now, and I'm thinking I'll throw in another dozen or two next time I order (at 3 bucks for a block 45mmx100mmx450mm, that seems doable). Only slightly annoying thing is that they don't have split faces, so I suspect I'll get a fair amount of waste after I split 'em. I'll probably go make a bunch of 'rough' dimensioned bracing stock and do a comparison test. Besides, better get all this kind of not-all-that-much-fun stuff done immediately, right? Already have all the soundboard cleats and centrestrip reinforcements I'll need in the next, oh, 5 years cut.

Also, since this stuff's sold by size, I have no clue how much it weighs. When suppliers say 1lb of bracing stock, how much volume are we talking? Any of you got fave suppliers for bracing stock, either Stika or Adirondack? I'll be annoying Rivolta about split bracing stock in the near future as well, though.Mattia Valente38406.1279861111

[QUOTE=Tim McKnight] Some braces make excellent kindling too.[/QUOTE]

I sometimes think that about whole guitars!

I also flex brace stock in a jig for deflection and rigorously throw out all but the stiffest. It's the cheapest component in any guitar but sloppy braces can ruin the best built instrument. I guess I only keep about 25% of my braces.

Colin

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The kids are learning....slowly, but they're learning, none the less.....

<bg>

Allright, I'll ask it. How do you tell when a brace is too flexible/floppy.
Inquiring minds want to know.

Jimmie, I think that's the value of what I learned. I've built only five to completion. I came into a stash of really old Sitka, and in Arkansas, that's gotta be rare. By replenishing my stock and being dead tired, it caused me to slow down and sit down and begin flexing and that is when I discovered the great variablilty in the brace stock.

It is something that can be measured. Roy O sent me Tim McKnights post from another forum and he learned the same thing I did. Braces are variable. And it goes like this, which one is best? Well, it ain't the rubbery flexible ones, but that is a hypothesis.

I even got in a thumping node-finding ring test to determine tone of the actual brace. It's incredible the variation in the tone of identically sized Sitka. You can hear even a small long piece of wood's ring if you hold it right. So I'm pretty pumped about this being an important factor in the way the guitar will sound in use. Not the only factor, but an important one.

Jimmie, I think picking braces is like picking strawberries. You find some that meet your criteria and run with those. The first step is learning there is a difference. To this point, I've not rejected a single brace, but from now on after establishing my own criteria, I'm testing every brace and rejecting any that don't measure up.

After you have sorted the braces according the the deflection numbers: Try dropping the brace from a set height and let it land on the end grain on your cast iron table saw top. Listen to the tone. Now separate them into two piles based on what you hear. I think you will get the hang of it. Besides it's easy to do from a seated position during a rest.

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tim...
http://www.mcknightguitars.com

Could one of you deflection numbers people give us an idea of what kinds of deflection you're getting? ie, at what dimensions are the braces, what weight are you adding, and what deflection are you getting?

I run all my braces through that deflection test as well. And Mattia, the specific test weight doesn't matter--per se--as long as your braces are all tested to the same standard. It's the comparison you're after. I use an old iron pipe wrench. And you can tell w/ a dial gauge the percentage of stiffness of one brace over another.
The floppier tops can get the stiffer braces, and vice versa. (To a point.) But this is an important place where a luthier can walk a finer line than a factory.

If you want to really add to the fun, Bruce, test the braces at 3/4" height, then sand off 1/16" and test them at 11/16" height. Your readings will surprise you. The stiffness is supposed to be a function of a cube of the height. But that is a generality. Some braces remain stiffer than others even if they are the same stiffness in the 3/4" test. I spoke w/ a professor here at out forestry school and told him of my findings and he said--yup, that's wood for you. These are the ones you want to scallop!Steve Kinnaird38406.570775463

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[QUOTE=Dickey] I've built only five to completion. [/QUOTE]

Bruce, Why did you make up 75 sets of braces? It seems likely that sometime in the next 10 years, or even two guitars from now, you'll want to change your bracing pattern. Are these braces already pre shaped or are they just cut into simple strips?

I'm not trying to be critical. I'm just curious as to what your thought processes are?

Mattia,

Considering estimating modulus of elasticity (E) (Young's modulus) which is a measure of flex under load. Nice thing is that it is independent of the size of the piece being measured (so you can compare tops of different thicknesses, etc.).

MOE

These estimates are precise when you average the results of three different weights. So for my deflection tests I use a series of weights; takes about 10 seconds. Don't use anything too heavy, because things get non-linear if you do.

One thing that's usually true is that as density increases so does a material's resistence to flexing under load. So without accounting for density, if we wanted material that was really stiff, we'd usually wind up chosing material that is also the heaviest (usually).

Very interesting thoughts. I have only braced 4 guitars and like Bruce, I used the braces that I cut for that particular guitar without thinking about comparing stiffness. I did use red spruce though and it did seem fairly stiff, but I guess compared to what? I did do deflection tests on the tops of the last 3 guitars I have going and recorded the results. I used 1 that I thought sounded about right and used that as a benchmark.What that is going to prove, I have no idea yet as the guitars aren't completely finished. Neat ideas though. I like Tim's method of dropping the cut braces on someting hard and listening to the sound, and then comparing the stiffness of the braces. I think it was Mario who said some time back that it's the sum of all the small things that can make a big difference in sound.I guess this is one of those "small" things. Thanks for the ideas.

I've never gotten into deflection testing, but some folks swear by it. I probably should give it a go. Get Dave Hurd's book: 'Left Brain Lutherie' for the whole poop.

Vic Firth Sticks. He got to listening to the sound of his sticks as he tapped them on a block, and began sorting them out by the tone. The only problem was that after a couple of hours sorting he (or his wife, who was really good at it) would get saturated and couln't do any more. When they started to fall behind on orders because of inability to sort them fast enough they put together a computerized system to do it.

Are you a drummer Alan?

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Mike, it was important for me to make seventy five sets, I made another twenty five sets today in what little shop time I had. Only this time there were eight sets of Adirondack.

The Adirondack were amazingly strong in comparison and each and every one were better braces than the best aged Sitka braces in this set of one hundred main xbraces.

Mike, when I made my first seven sets of shaped xbraces and glued them up and hung them on a dowel under a shelf I thought they'd last forever. Well last week, I used the last one, so I needed more. And truth is, many of the less desirable ones will now be culled, no point in using them for xbraces.

Secondly Mike, If I hadn't made so many I wouldn't have been tired and sat down and starting to flex braces. In other words, by doing so many and handling so many I got quantitative analysis going on. That would not have happened and i wouldn't have learned a thing if I just made a few sets.

Some things you learn by doing. And the old addage is true, the more I know, the more I realize that I don't know.

Bruce, man is that the truth! Seems like the more I find out about this craft, the worse my guitars seem to look.

I think I got too fired up and was trying to do some things that I wasn't equipped to do. Now I'm trying to settle down and just take whatever amount of time it takes to do it well.

Hopefully this will improve the quality of my work and also give my brain a little rest from trying to figure out things I don't need to know yet.

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Dave Rector
Rector Guitars

One thing I have noticed on some brace stock is that after you cut it the braces will bow.

I am only using split stock, and it is all well seasoned, but I recently had a whole billet of Adirondack that bowed like crazy after they were cut off the billet -- maybe a quarter to a half inch of bow across the length of an x brace. I am not sure what causes that but I hate to waste the wood.

Now I have lots of ergonomic push sticks.   

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Brock Poling
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Sounds like you got an odd piece of Adirondack Brock. John Griffin supplies some of the best brace stock, it's expensive. www.adirondackspruce.com

I only had one piece out of all the sitka do the curve thing, which is pretty amazing. Time for more testing, but the cursory test yesterday led me to believe addy is the way to go for strength, stiffness, and consistency.

Reaction wood will do that. If the tree grew on an incline, there will be built-in tension that when you split it, releases itself. If the tree grew with a twist, ditto. If you're too near the stump, ditto again.

The important thing is that you noticed it, and tossed the pieces, right? Spruce is cheap; don't use bad spruce.