Saturday, October 8, 2011

shaping braces

 The back bracing needed to be shaped and contoured, and this process started with a block plane, then a small brass plane and chisel....

...and then a scraper and abrasive paper from 120-240-320-400-800 grit, then burnished with the back of the paper. I'll probably treat the whole interior with horsetail grass to burnish it further and to impregnate the surface with silica (glass). That would not be a conventional thing to do in guitar making, but I find it advantageous (with deep historical precedent) in violins. The shaping operation is incomplete in this picture.


  1. She is lookin' ohhh sooo fine!!!

  2. I have so many questions. How does one know the shape and density of the braces? Can you tell by feel, as I would know intuitively the scantlings required in a boat?
    I occasionally worked with Mary while she was shaping the belly and back of her violin and could see and feel the contours required, but had little understanding of "why".


  3. Hi both.
    The shapes and densities of these things are pretty much set by convention- with some evolution. To be a guitar it has to make noises within certain parameters and expectations, and it has to be shaped recognizably too. So to find these dimensions you'll start by studying what others have done, or work from plans. The variations you make for 'this sound' or that piece of spruce' will only be refinements....remembering that most guitars are mass produced out of very cheap materials, but they still sound like guitars.

    It's only when we want to make something special that we'd vary much from convention- and even then it will be nuance rather than revolution. So we might want to increase sustain, or warmth, or volume or transient response, or brightness and we can make acoustic judgements based not on the dimensions of your average wood, but on 'this piece' according to our experience and how it feels and sounds in the hand.
    If you're lucky you have an experienced teacher who is capable of explaining what feels good bad or dead. But it's like any sensitivity- boats or sport etc, you just develop it by pushing yourself into it over and over.
    Even in a really good guitar factory, there isn't anyone fussing over the shape of the back braces because this week's spruce feels a little springier. It'll just be the same shape as last week, and maybe someone will notice a slight difference between this instrument and that one, but probably not.

    The fine handmade article will just sparkle a little more because someone's taste was in charge of the collections of tiny decisions that add up to an instrument that maybe has some extended capacities and sensitivities.

  4. The dificulty comes when bracing the soundboard. Im 100% spcialized in flamenco guitars and untill now I´ve built 90 of them and I´m just getting close to controling all the parameters.
    And since every piece of wood is different, you cant really meassure but have to trust fingertip feel and tap tones.
    When all that comes together, you have a very fine specimen, the flamenco guitar. A supersensitive, lightweight and percussive beast that reacts to your smallest change in pulsation

  5. Thanks for your input Anders, I enjoy your blog too.