Help. Question: Grain Orientation on Bracing

Rob plays without finger nails. If you are accustomed to players using nails (the vast, vast majority) you might perceive that as a slight muddy sound.
I love that 'old fashioned' tone he gets. I'm not saying it's better than nail players, it's just different. Gives variety in a world where many musicians can sound too similar. Celebrate the difference.
Of course the top is thicker than a similar guitar with bracing. I don't know how long it will hold up. Strictly speaking it wasn't made as a commercial instrument but built as an experimental one, to copy what Torres had done over 100 years ago. I did sell it and the guy who bought it has ordered a different model, so presumably it's still holding up. He hasn't told me that the action is becoming difficult - a sure sign that the top is distorting.
No, the bridge wings don't go all the way to the soundboard edge.
 
1- Braces first priority is to stop the top dying a quick death due to string pull (tension).

2- Drums have no pulling tension, hence no need for braces as such.

3- That braces can be used to define sound wasn't an original priority, but it became a welcomed consequence of lightening brace mass (scalloping etc)

4- Any mass that absorbs vibration (energy) is bad. Therefore, your theory that fig 1 grain orientation is bad due to the vibrations bouncing back off the winter grain is false. If this were true, it would be a good thing as you want as much energy in the top plate as possible, and least amount as possible in braces, bridge, sides and other mass which act like a heat sink to sound vibration.
 
Beau Hannam Ukuleles said:
4- Any mass that absorbs vibration (energy) is bad. Therefore, your theory that fig 1 grain orientation is bad due to the vibrations bouncing back off the winter grain is false. If this were true, it would be a good thing as you want as much energy in the top plate as possible, and least amount as possible in braces, bridge, sides and other mass which act like a heat sink to sound vibration.
Click to expand...

I like your theory Beau and I agree with you. See below of what I think you are saying:

DSCN7865.jpg

Figure 1 shows the vibration bouncing off the winter grain and back to the top. Figure 2 shows the vibration being absorbed in the soft summer grain.

However, from a structural standpoint I think figure 1 is inherently weaker as shown in the bottom two figures.

I'm sure some of you might be rolling your eyes and thinking that I'm over thinking. But I think these subtleties can make the difference between a good sounding instrument and a great one.
 
Fig 2 is better as the very dubious problems with the winter grain bouncing thing isn't worth worrying about.
Even if it WAS correct, id still use the fig 2 (quarter sawn) orientation for stiffness benefits.
 
With the wavelengths we are dealing with you are not going to get vibrations bouncing off of winter grain or summer.
 
This is the crux. You really need to know how these things work before coming to any firm conclusions. It's far too easy to visualise these things and then start drawing all manner of false conclusions. Clearly the best approach is to dig out and read all the theory - Gore is the obvious one. You obviously don't need any science to build first rate instruments but if you start trying to tell people how these things work you'd better come armed with some decent background. Alternately you can do what I do. Keep quiet, build, do your best and hope that the world likes your work. That's the old fashioned way.
 
Michael N. said:
This is the crux. You really need to know how these things work before coming to any firm conclusions. It's far too easy to visualise these things and then start drawing all manner of false conclusions. Clearly the best approach is to dig out and read all the theory - Gore is the obvious one. You obviously don't need any science to build first rate instruments but if you start trying to tell people how these things work you'd better come armed with some decent background. Alternately you can do what I do. Keep quiet, build, do your best and hope that the world likes your work. That's the old fashioned way.
Click to expand...

Aloha Michael! It is not just a word, it is way of being. Aloha!
 
Once again, I'm just a piano guy. So, I don't have any answers but find this topic most fascinating. Seems to me there's a believable argument that figure 1 braces might have some benefit to sound over figure 2 braces. Another is figure 2 braces may be better for strength. But my question is still this: Do the very best made, most acoustically effective braces benefit the sound? Strength and durability aside, would the instrument sound better without bracing?
 
Further, is it possible that there's a way to design the bracing of a soundboard using the stronger grain direction where it's needed and the more acoustically beneficiall braces where they would help the sound? (the least negative of both worlds)
 
I've built both over- and underbraced tops. I've built with tops too thin and too thick. It's not hard to make a mess of things but it's really not that hard to get it right either. I take extra care when I work with woods I haven't used before or when there are other variations to consider.

But grain lines reflecting vibrations, or "sound" back into the soundboard..? If I google "overthinking" I expect to find that sketch, sorry Sequoia!

I won't claim to have a simple and logical sounding explanation to how soundboards move but often people seem to think that vibrations, or "sound", are shot like laser beams from the bridge end of the strings, down through the saddle, exciting the completely isolated soundboard where the "sound" is amplified and then shot out the soundhole like a strong wind.

I simply do not think that's the way it works. I use braces with the grain peroendicular to the top by the way.
 
I don't think you can seperate the strength from sound as you put it. The inherantly stronger per a given size and weight in general the greater sound. Material density has an effec as well but for what we are taling about I would say minimal. Thus if a brace is stronger in a given grain direction lighter stock can be used. This will generally produce greater volume and less dampening.
 
stevepetergal said:
Once again, I'm just a piano guy. So, I don't have any answers but find this topic most fascinating. Seems to me there's a believable argument that figure 1 braces might have some benefit to sound over figure 2 braces. Another is figure 2 braces may be better for strength. But my question is still this: Do the very best made, most acoustically effective braces benefit the sound? Strength and durability aside, would the instrument sound better without bracing?
Click to expand...

The thing with softwoods is that they are stiffest when the grain lines are standing upright at 90 degrees. As you go off 90 degrees the stiffness decreases. Worth taking a look at,


In softwoods grain angles greater than a few degrees produce a markedly disproportionate reduction in tensile/compressive strength — maybe 25% reduction at just 15° and 50% reduction at 30°. The decrease in stiffness is even greater. Hence, as stated previously, the need to use boards that allow all structural members cut from them to have a maximum grain slope better than 1:15 (4°), or perhaps 1:20 (3°) for critical structures, throughout the component. (The structural member can be sawn from the board in a manner that produces minimum grain slope within that member.)

https://www.recreationalflying.com/tutorials/scratchbuilder/timber.html
Click to expand...
 
Sven said:
that vibrations, or "sound", are shot like laser beams from the bridge end of the strings, down through the saddle, exciting the completely isolated soundboard where the "sound" is amplified and then shot out the soundhole like a strong wind.
Click to expand...

Like a "Mighty Wind!" Arrows of sound shooting out of the wood!... Sven I have to agree with you. There is thinking and then there is over thinking. But gosh darnit, I liked drawing those arrows shooting through the wood. Does it work that way? Probably not.... But seriously, structural strength has to trump everything in the end and thus grain perpendicular I think.
 
You must log in or register to reply here.

Similar threads

K
Please help a newbie with a low G question!
Replies
13
Views
970
Twang Banger
Twang Banger
J
Help - question about faulty bracing
Replies
4
Views
577
Michael Smith
Michael Smith
iamesperambient
question/help in regards to my new konablaster baritone uke
Replies
7
Views
663
iamesperambient
iamesperambient
BIGDB
Question and help about guitar to ukulele chords
Replies
2
Views
317
UkeKiddinMe
UkeKiddinMe
H
  • Locked
Help, with a forum etiquette question
Replies
13
Views
1K
buddhuu
buddhuu
Top Bottom