Guess even the great one's change their "science" --- here's one of his essays, note the floor joist analogy:
http://www.esomogyi.com/principles.html
Brian Burns early tonewood testing
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Darryl Young
- Posts: 1668
- Joined: Fri Jul 30, 2010 6:44 pm
- Location: Arkansas
Re: Brian Burns early tonewood testing
Brians tests results seem about right to me. Al Carruth has stated his tests show a strong correlation between stiffness along the grain and density (in the softwood species he tested.........a few spruce species, cedar, and some redwood IIRC).
Since I tend to triangulate the cross sectional shape of my braces, I'm more comfortable using vertical grain orientation than horizontal. If I used horizontal grain, after tuning there may be a thin, narrow section of a grain layer left on top of the brace which might have a tendency to split off if it accidentally gets bumped (or could string vibration over time tend to do this?). Since the stiffness goes up/down with the cube of the brace height, a small piece splitting off will impact the stiffness of the brace. If the grain is oriented vertically, the center grain layer would run the entire height of the brace and, at least in my mind, seems less likely for the peak of a scallop to split off if using vertical grain orientation.
BTW, i can't imagine that rift grain orientation would be as strong as vertical or horizontal........but of course I haven't tested it. In soundboards, rift sawn tends to reduce cross grain stiffness but that's not much of an issue for a brace. Seems runout is the biggest thing to avoid in a brace.
Since I tend to triangulate the cross sectional shape of my braces, I'm more comfortable using vertical grain orientation than horizontal. If I used horizontal grain, after tuning there may be a thin, narrow section of a grain layer left on top of the brace which might have a tendency to split off if it accidentally gets bumped (or could string vibration over time tend to do this?). Since the stiffness goes up/down with the cube of the brace height, a small piece splitting off will impact the stiffness of the brace. If the grain is oriented vertically, the center grain layer would run the entire height of the brace and, at least in my mind, seems less likely for the peak of a scallop to split off if using vertical grain orientation.
BTW, i can't imagine that rift grain orientation would be as strong as vertical or horizontal........but of course I haven't tested it. In soundboards, rift sawn tends to reduce cross grain stiffness but that's not much of an issue for a brace. Seems runout is the biggest thing to avoid in a brace.
Last edited by Darryl Young on Wed Aug 10, 2011 5:08 pm, edited 2 times in total.
Slacker......
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Herman
Re: Brian Burns early tonewood testing
Good thinking on the triangle shape issue Darryl. You have a point there.
This evening I did a little test. Took some englemann, sitka and eurospruce.
I did saw them into equal square braces and measured the deflection under a load. Simple.
Guess what: Each piece was stiffer by far with the grain vertical and less stiff with the grain horizontal.
Hmm.
This evening I did a little test. Took some englemann, sitka and eurospruce.
I did saw them into equal square braces and measured the deflection under a load. Simple.
Guess what: Each piece was stiffer by far with the grain vertical and less stiff with the grain horizontal.
Hmm.
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kencierp
Re: Brian Burns early tonewood testing
Herman --- I have been constructing model airplanes, building homes, making and selling furniture, making fixtures for automotive on and on etc. My beliefs and conclusions follow exactly what you saw in your experiment - my personal experiments also had the same results as yours -- so I conclude that I must be missing something -- perhaps wood acts differently in my shops?
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Tony_in_NYC
- Posts: 827
- Joined: Thu Aug 12, 2010 9:11 pm
Re: Brian Burns early tonewood testing
Yes Ken. Wood does act differently in your shop. In many shops wood is wasted and ruined and tossed away. In your shop, wood is turned into sweet guitar kits that have so much potential. Then, once shipped off to the end user, the wood is wasted and ruined and tossed away in some cases. LOL
In my mind, and I am not a strengths of materials expert, but it seems that trees have the grain oriented a certain way for strength, right? Wouldnt we want to keep the orientation the same when we cut the tree into little bitty slices to make guitars with? If the best orientation of the grain lines was flat sawn, trees would not grow with radial rings. They would grow like flat planks. So why alter that when you make anything with wood where strength is a concern? Maybe I am just a maverick in my thinking.
In my mind, and I am not a strengths of materials expert, but it seems that trees have the grain oriented a certain way for strength, right? Wouldnt we want to keep the orientation the same when we cut the tree into little bitty slices to make guitars with? If the best orientation of the grain lines was flat sawn, trees would not grow with radial rings. They would grow like flat planks. So why alter that when you make anything with wood where strength is a concern? Maybe I am just a maverick in my thinking.
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Herman
Re: Brian Burns early tonewood testing
Now I'm sure, There lies a spell on my shop. My wood is in another universe where things are upside down. Well, 8 x 12 feet is hardly a shop. More a closet. Maybe it"s a little spell, so there is hope.