Thursday, October 6, 2011

calling in the reinforcements

 Most of my violin family instruments have had linings made from best English Willow (recycled from cricket bats). This is a light and resonant timber which also bends and carves very easily. Classical guitars often employ mahogany or Basswood, or maybe Spruce for the linings, and while some makers used un-kerfed shapes steam bent to fit, most seem to use a kerfed profile. Steel stringed guitars nearly all have kerfed linings and that's what I'll do here. Mahogany is a brilliant timber, but supply has a dismal history and I'm interested in alternatives.

The purpose of the lining is to increase gluing surface area at the edges, and while on violin family instruments this is largely because the sides (ribs) are so thin, in guitars it is mainly because of the intrusion into the edges of the bindings that cut a swath through both the sides and the plates.

The pic above shows my linings in the process of being shaped, first with a plane and then rounded with a scraper. These are from an unbelievably beautiful stock of very old (and old-growth) New Zealand Kauri that I have had for years. It was part of a fit-out in the 1940's- mainly cupboard shelving that was being discarded in a building up-grade. It is resonant, absolutely even in density and silky smooth yellow to purple with sparkly accents when cut on the quarter. I love this stuff to bits and really enjoy lifting it to the status of precious jewels when using it. (Kerfing it is a bit annoying really...I'm caught between honouring traditional technique and honouring magnificent materials)
 And here, above is the rather boring and repetitive job of hand cutting the kerfs which allow thick material more easily to take up a complex shape. The pic shows two lengths, bottom edges together, being done simultaneously. You can buy machine kerfed stuff, or use a machine yourself to work faster, but what's the point? There is too much machine work in the average guitar already and an extra hour or two is a nice time to get to know the guts of the instrument.
And here is a shamefully rough shot of the beginnings of the belly, or soundboard bracing. The big cross brace has it's halving joint, and the smaller braces are being assembled and cut to fit the arch and length. I'm hoping that will all look spick and span soon. The soundboard really is EVERYTHING on a guitar, acoustically speaking. It is a little piano soundboard made in miniature, and tuned to hold in your lap.

You might notice the grain orientation in the braces. The grain is vertical, and while there has been argument over whether vertical or horizontal grain is strongest, there is general agreement, I think, that in terms of stability, verticality is king. In any case this is the way it has always been done, and it has worked for the Masters. These braces were planed flat from split flitches, to ensure integrity of the grain. (they are actually split from violin belly wood flitches, split in the Italian Alps in the 1980's....make your mouth water just holding it)

Putting the braces into some sort of tragic perspective, these cost me more than the price of three complete student budget guitars from my local music shop. What I'm doing just doesn't make cents [sic].


  1. I love that what you are doing here does not necessarily make "cents"...its a very endearing quality in you...

  2. Rob this is a real treat, both the work and your thinking that is going in to it. Sometimes "cents" just need to look after themselves.

  3. Thanks Mike. I'm grateful for your interest.