Radiusing the Sides

I’m currently using an old-fashioned, hands-on technique to dimension the sides. The sides (or rim) need to be tapered since the tail of the guitar is deeper than the heel. In addtion they need to be radiused since both the top and back are domed rather than flat. Some makers don’t radius their tops and have had a lot of success using that approach (Kevin Ryan and Jim Olson) but I’m not there yet. I still feel more comfortable with the added strength the domed shape gives.

Sanding dish planes and chisels

I use a block plane to remove stock, taking it pretty liberally from the heel block and a lot more conservatively from the tail.  I own a slew of planes, some of which I acquired years ago when I was a carpenter but most of the ones I use now I’ve acquired over the last few years.  I’m particularly fond of Lie-Nielsen planes.  They’re heavy and really precisely machined.  They’re worth the cost.  Some things you can go cheap on but planes usually aren’t one of them.  A good plane is a joy to use and a bad one is a pain in the butt.  I bought an inexpensive jack plane a few years back and ended up throwing it away.  The mouth was machined a degree or more off square which made the thing useless.  Planes need to be sharp, too.

Anyway, I repeatedly lay the guitar in the radius dish and look for light.  Wherever it’s touching I remove stock.  When it gets close I mark the exposed wood with a big piece of chalk I swiped from my daughter and begin to sand.  When the the chalk is gone you’re there.

I make index marks on the inside of the two blocks on both sides when I start on the back.  The back takes four times as long to do since there is so much stock to remove.  The principle is the same but you have to be careful.  I use a 30 foot radius dish for the top and a 12 foot for the back on all of my guitars so the back ends up being much more radiused or “curvy”.  Some folks will say this radiates sound toward the soundhole which may be true but I just think radiused backs are cool.  They fit in the lap better and just look and feel nice.  Because of the radius, however, you’ll end up taking more stock off the bouts than the waist.  I try not to hurry, using the same technique as the top, putting the sides in the radius dish and using a backlight to check for gaps often.  Also, as I remove stock I periodically check with a ruler to see if I’m taking off stock symetrically.  When I’m close I chalk up the edge and sand away.

Using a backlight to check for gaps Ready for hole filling

This process takes at least a couple of hours, often more.  I’m constantly looking for ways to reduce the time it takes to make guitars and improve the quality.  This is one of those things that can be sped up and I’m working on a jig to do just that.  Anytime you find yourself spending hours removing stock you can probably assume that this might be a good area to innovate (or steal as the case may be).  I was out in Kevin Ryan’s shop last week and Kevin uses a really neat jig to radius the backs of his guitars.  I plan on using his jig as a model to do the same.  Kevin’s shop is really wonderful.  I think he enjoys making tools and jigs more than he likes building guitars. 

Kevin had just finished a “Ghost” guitar which has a redwood top that had been submerged for quite some time giving it unusual tonal qualities.  I got a chance to play it for a while and it was wonderful.  He builds great guitars.  Heck of a nice guy, too.

This guitar uses some old Brazilian Rosewood and, like a lot of the stuff available today, needs some work.  There are a dozen small wormholes and two larger ones that need to be filled.  That’s next. 

(The guitar is further along than the blog so I hope to make several posts in the next week.  Thanks for checking in.)

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