Does the left brain plate tuning method work for completed guitars?

[Kevin Bryden]

I am interested in buying this book. It's on amazon uk for £137 Although I won't be having it if I can't get it cheaper.

Thanks

[Alan Carruth]

If you're talking about Dave Hurd's 'Left Brain Lutherie', I suspect it does. I've never tried it myself, since I use another method that seems to do substantially the same thing, but the fact that both of us end up at the same place indicates that either method will work.

Alan Carruth / Luthier

[Bob Gramann]

You can buy the book directly from David for quite a bit less (ukuleles.com).

[Kevin Bryden]

Thanks for the replies. Are there any printed guides to the method you use Alan? And, can that method be employed post build? I read some of David's book on google books and he talks about test the top prior to gluing the bridge on.

Thanks again.

[Alan Carruth]

I wrote a series of articles in 'American Lutherie' magazine 'way back on 'free' plate tuning; they're in the first 'Big Red Book', iirc. As the name implies, this is a method you use on the top and back when they're 'free' of the body, before assembly of the box. You can learn some things by looking at the assembed modes, but less than you do from the free plates. Basically, any reasonable facsimile of a guitar will have pretty much the same resonant mode shapes when it's assembled. The frequencies vary some, of course, but less than you might think over a pretty wide range of quality. Thus the assembled modes don't tell you as much as the 'free' plates. Dave's deflection measurements are actually better in that regard than mode shape data.

Alan Carruth / Luthier

[Jason Rodgers]

I have the book, and it's good stuff. Yes, you can do the deflection testing on completed instruments. Actually, this is how Hurd went about establishing deflection targets for his own instruments: he measured the best instruments he could get his hands on and shot for those numbers. Obviously, you could do this on a glued-up box, before finishing, and then fine-tune. As with Al's method, I guess the trick is figuring out where to shave and sand to allow more deflection in specific areas, and then figure out what to do when you go too far!