braces (Full Version)

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El Burdo -> braces (Jan. 3 2012 11:44:21)

I have made fan braces which are occasionally (in the same brace) slightly less than the 6mm width specified in my Santos drawing - I had to cut them by hand by which I mean no table saw etc.

My inner craftsman feels I ought to start again but my inner conservationist thinks it would be wrong to throw the wood away for the sake of .5mm max. As flamencos are supposed to have light bracing is this going to make any significant difference? - as I understand it, lightness is good although I do see discussion on designs where bass side braces are 1mm wider than treble side. The length which I guess is probably more important is fine.

Thanks.



El Burdo -> RE: braces (Jan. 3 2012 11:49:12)

I'd throw them away.

Your inner craftsman.



El Burdo -> RE: braces (Jan. 3 2012 11:51:56)

I'd keep them.

Your inner conservationist.



Anders Eliasson -> RE: braces (Jan. 3 2012 11:57:59)

Make them a little bit thicker and thats it.
Sorry to have interfered in your deep inner discussion.



El Burdo -> RE: braces (Jan. 3 2012 12:23:58)

Do you mean, they will be too thin as they are?

I'm more than happy to be interrupted!



Stephen Eden -> RE: braces (Jan. 3 2012 13:39:59)

Hehe I love your own dialogue!! I use 5mm Bracing. If the are on the thin side make them taller. The Santos plan in the Courtnell book has 7mm bracing! So you can see the even he mixed it up a bit!



Anders Eliasson -> RE: braces (Jan. 3 2012 15:01:12)

thicker, taller, fatter. whatever. Its about getting the right stiffness

Its not the same making a brace slimmer and taller and another wider and lower. they´ll act diferently. Its the fibre that are furthest away from the plate that produces most stiffness. So a square brace 4mm wide and 5mm tall will be stiffer than one being 5mm wide and 4mm tall. We are talking about using the same piece of wood.



Sean -> RE: braces (Jan. 3 2012 15:31:30)

The height of the brace is more important in regards to stiffness then the width is. Going taller and narrower gives you a lighter stiffer brace then shorter wider but there are limits as you give up contact patch for gluing, also the weight savings are negligible in comparison to the soundboard itself and bridge. The height you will have to work out on your own the same as the soundboard thickness to give you your desired flex, this just comes from experience making guitars not books or plans.
The short answer, if they're all dimensional the same flex them and if any are noticeably more flexible throw those in the waste bin.



El Burdo -> RE: braces (Jan. 3 2012 15:39:34)

I think that's why I was starting to worry; these are all 6mm wide and only 3.5mm at the tallest point - the apex of the 'roof' so to speak. Looking at pictures here and elsewhere they seem much taller. I am sticking to the plan where I can for this one.
Thanks for the insights as usual - I'll flex them as you suggest Sean and make another set if they seem weak.



Ricardo -> RE: braces (Jan. 3 2012 16:19:16)

quote:

So a square brace 4mm wide and 5mm tall will be...


a rectangle? [:D][:D]



C. Vega -> RE: braces (Jan. 3 2012 16:45:12)

Bracing dimensions should depend on the stiffness and other qualities of the materials being used both for the bracing itself and, even more importantly, the soundboard and the end result that you're aiming for.
Specifications given in books and even measurements taken directly from old master instruments will give you some guidelines to work from but not an ideal set of specs unless the wood that you have is exactly the same as that in the original instrument which is most unlikely.
I think that you can safely bet that Santos and the rest of the old boys rarely, if ever, braced a guitar exactly the same way twice.
Go with what you have and stop worrying so much about it. Life's too short.



rombsix -> RE: braces (Jan. 3 2012 18:43:16)

quote:

a rectangle?





Anders Eliasson -> RE: braces (Jan. 3 2012 21:39:11)

quote:

Go with what you have and stop worrying so much about it. Life's too short.


Exactly. You have 6 x 3,5mm. You can leave it totally square for max stiffness, you can slightly round it for a slightly less stiffness and you can shave off the sides and make it a triangel 6mm wide and 3,5mm tall for little stiffness....
With your 6x3,5mm braces you have the whole world in front of you and just the same as living life, you have to find out yourself.

BTW, 6x3,5mm is more or less what I work with...



El Burdo -> RE: braces (Jan. 3 2012 21:54:06)

Thanks Anders - that's very helpful - about braces, and life too.[;)]

I'm going to leave them squared off, glue them in, then shape the tops, probably equally across all seven and try and get a feel for the rigidity of the tapa. I want to try and obtain a recognisable and high pitch to the tapa (I know there is a debate there too...) I like the idea of tapping and shaving, tapping and shaving. I have already shaped the 'roofs' of the current braces so am making some more from the remains of the tapa. It doesn't feel so much like a waste of wood that way.

Thanks everyone!



El Burdo -> RE: braces (Jan. 3 2012 21:56:12)

Yes, thanks.

My inner voices.

(That's enough inner voices Ed.)



krichards -> RE: braces (Jan. 4 2012 7:37:24)

Double the width gives double the stiffness
but double the height gives 8 times the stiffness (2x2x2). Its called the 'cube rule' by engineers I believe.
The trick is to know what stiffness you need and that really only comes with experience. Plans are only a guide because your wood is different in stiffness from theirs. You just have to proceed by trial and error/improvement.



Anders Eliasson -> RE: braces (Jan. 4 2012 8:49:18)

Yes and also, plans never give info on the final shape of the brace.



Stephen Eden -> RE: braces (Jan. 4 2012 13:33:50)

haha Seems Like TB would feel right at home in here with all this talk about shaving braces!



Anders Eliasson -> RE: braces (Jan. 4 2012 16:19:08)

sssshhhh[8D]



C. Vega -> RE: braces (Jan. 4 2012 17:13:49)

Good ol' Mr. Salty Finger has been kinda quiet lately.



El Burdo -> RE: braces (Jan. 4 2012 18:13:37)

Oi!

Back to the subject please....

A stiff top will propagate high frequencies better then a 'floppy' top I'm thinking. If you want some distribution across the frequency range you should reduce the stiffness? Is that right? I'm just going to try and produce a vibrating top that feels good - but it may be all bass.
What note range should I be listening for on tuning the top to? If this has been done I can't find it, sorry!



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