Neat video on guitar making

vince

Some of you may enjoy this short video of a flamenco guitar being made. The little grains vibrating on the soundboard was neat — is this a common technique?

http://vimeo.com/43005056

Cheers,
Vince

noodlenot

very well done, but in a way - to my eyes and hears - sort of bloated. most guys i know will build a guitar (except polishing) in +-100 hours. in a way the clip looks more about the author of the video than about the author of the guitar (in a portfolio kind of way, not that that´s a bad thing). still, it´s very well crafted and a pleasure to look at.

the grains popping are chladni patterns. the top is being driven by - say - a sine wave from a robust loudspeaker and will vibrate in patterns related to the driving frequency; the grains will fall within the node lines of that particular mode. rather common practice. people like to use more catchy names for it, though - usually "tuning" or "voicing" a top. it´s basically an assessment of the stiffness of the soundboard (both overall and localized stiffness variations) that will give you clues about plate thickness and - eventually - about brace height.

cheers,
miguel.

Bones

Yes it's commonly done. It's a good idea to keep track of the modes and responsiveness to get a database of as-built parameters to help to decide how to tune the top and back.

Once you've done a few and know about where the 'nodes' are located (areas of low displacement) you can simply pinch a node between your thumb and finger and suspend the top and tap at an 'anti-node' to excite each mode. This is what they call 'tap tuning' and accomplishes basically the same thing with less work but requires experience and 'feel'.