Cyr Custom Guitars started another acoustic instrument project--this time an 12-String Acoustic Guitar. This guitar will have a jumbo body with a really nice bearclaw-figured top and claro walnut sides and back. We'll be able to use most of the same tools that were acquired or built for the acoustic guitar project, and then used on the Acousic Bass Guitar projects. This project, like the acoustic basses, is much more of a "from-scratch" project than the Dreadnaught guitar was, in that we're going to hand-make the neck and top rather than purchase them already made up.

This instrument is to some degree a custom design, using essentially the same layout for top and back bracing that the dreadnought acoustic guitar used, with slight modifications to account for the Jumbo body shape. In fact, except for the placement of the bridge plate, this body will be nearly identical to the one built for the acoustic basses. The other difference is a somewhat thinner top - about .110", whereas the basses were built with tops .125" thick.

The first picture shows the top with the rosette inlaid into it:

The rosette uses B/W/B/W/B purfling for the inner and outer rings, and 1/8" wide paua abalone with B/W/B purfling in the wider center ring. The purflings came from LMII and Grizzly Industrial, and the abalone came from DePaule Supply. Another picture showing the bearclaw figure in this top a little better:

The top is from Bob Tibbetts at www.guitarwoods.net.

Gluing the top braces:

The back and sides were sanded to thickness on the large belt thickness sander at Hank Mauel's shop in Auburn. At Hank's suggestion, we sanded the back and sides to .090" thickness, so they're rather delicate.

The back braces have been glued in place:

With some help from Hank Mauel (www.mauelguitars.com), I got the sides for this guitar bent to shape last week. Actually, Hank did the bending, and showed me how it's done, so that I can do it myself when I get the side-bending machine built. First I had to make a form the shape of this guitar body:

Once this was done, I was off to Hank's shop in Auburn, and got the sides bent. Next step was to glue the neck and taoil block to the sides. This next picture shows the gluing of the neck block to the body sides:

Note the dark streak on the upper right portion of the body. A small crack developed in the walnut during the bending process, and the dark streak is the superglue Hank applied to repair it.

Next I prepared the body rim for the attachment of the back by gluing in the kerfing, which is basswood reverse kerfing that I bought from Bob Tibbetts at www.guitarwoods.net. Then I trimmed the back braces and kerfing to fit, and used my 20-ft radius MDF dish with 80-grit sandpaper to sand the back edge of the rim to the right curvature to accept the back. Here's the body rim with the back glued in place:

Note that I have also installed the side braces in this picture. They're made of 3/32" x 5/16" Bolivian rosewood, cut on the new Ridgid 14" bandsaw.

The next step was to remove the clamps from the neck headplate, and here's what the neck looks like with the headplate glued on:

Neck with the headplate shaped and sanded smooth. Note that the position markers (1/4" abalone dots) are installed but not sanded down yet:

Back of the headstock, showing the flame figure and the black walnut skunk stripe:

The body is now ready for the binding/purfling channels to be cut:

The body from the back, showing the figure in the claro walnut that the back & sides are made of:

I forgot to take pictures while the bindings were being installed. here's the top after the bindings were finished & sanded smooth:

More shots of the body after the bindings were installed. These bindings were made by laminating walnut and maple veneer to a 3/16" tchick sheet of very tightly figured flame maple, then slicing off 1/10" thick strips off of that. The backstrip is a D35-style backstrip from LMII:

Another shot of the body, showing the abalone purfling and the bindings near the neck mortise joint:

More shots of the body that show off the abalone purflings and the soundhole rosette. The abalone was purchased from Andy DePaule:

More shots of the body with the neck attached. There is no finish on the them at this point:

More still of the body with the neck bolted on:

This is the body with three coats of System Three SB112 epoxy pore filler applied. Each coat of the epoxy takes about 24 hours to cure fully. After this coat is cured, I will sand it smooth with 400-grit sandpaper and it will be ready for final finishing. The plan is to use LMII's KTM9 waterborne lacquer finish:

Another shot of the body after the third coat of System Three epoxy was applied:

This is the neck with one coat of System Three epoxy:

Another shot of the neck after the System Three was applied, showing the detail on the heel cap:

Another picture of the back of the headstock, showing the spectacular figure of the maple in this neck:

This is the front of the body, with a couple coats of KTM-9 waterborne lacquer applied over three coats of SystemThree epoxy filler. Note the blue tape which keeps the wood bare for gluing the neck and bridge in place. The bearclaw figure shows really well in this picture!

May 23, 2006: Over the last few days I did the following:

  • Made the bridge and glued it to the body
  • Mounted the tuning machines on the headstock and installed the neck to the body
  • Drilled and reamed the holes for the string pegs in the bridge

And tonight I strung her up for the first time. Here are the pictures:

She really sounds good--that wispy, sweet sound you expect from a 12-string, but the lows are phenomenal! I built this one with a jumbo body shape, but with the depth of a dreadnaught, to give her plenty of low end, and the strategy worked. Well. I like it!

 

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(c) Copyright 2005 by Stephen Cyr
Last updated November 9, 2005

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