Acoustic Guitar Construction

Status, Git #3, East Texas Red, 07/25/14
Will Reyer

Stupidity may still be alive and well. Continuing my building with local lumber, found objects, and anything inexpensive.

This guitar uses .075” sides of plain-sawn red oak from the skid of a pallet. The second one came out of my Fox bender with a split in the lower bout, so had to make a new side for the bass side with nail holes in it as that was all that was left (dark spots on upper bout near back).

Soundboard and back are 1/8” Russian birch plywood. Heel block is (nominal) 1/2” Equadorian plywood, head block is 1” yellow poplar laminations. Reverse-kerfed linings are basswood, soundboard bracing is white pine scraps selected for quarter-sawn grain from common lumber.

The body is 3-1/8” deep, with soundboard and back parallel, because it's based on my #2 guitar which I built out of the practice sides for a square-neck resonator, and sounded amazingly good with ¼”underlayment plywood top and back, silhouette from a Santa Cruz Orchestra Model.
( see: viewtopic.php?f=24&t=1609 )

Bindings on this are .250” x .100” plain-sawn cherry, which bent very nicely. Fretboard and bridge will also be plain-sawn cherry. The neck is plain-sawn yellow poplar with a ¼” cherry stripe. Nut and saddle will be 1/4” Corian from a sink cut-out on hand.

Finish on body started with sanding sealer. I used to use Benjamin Moore for woodworking, but it's no longer made – this is Cabot's. This is a great aid to preventing tear-out when routing the soundboard and back flush with the sides and cutting the binding rabbets.

On top of this are two coats of Minwax Clear Satin Wiping Polyurethane. Never used this before, but love it. It's retardedly easy. I used to spray lots of lacquer when I was a Wood Modelmaker in undergrad days but I'm not interested in the hassle in my old age, or the fumes. Shiny doesn't impress me, I like to see the wood. A guitar ought to be easy to play and sound good, the rest isn't mandatory. When I was a boy the hot-rodders used to say, “If it don't go, chrome it.” I want to get it down to the minimum requirements.

This time I took Ken Cierpilowski's tip, sloping the top rim from the waist down 1/8” at the head block via a board attached to a router base that would span my female mould, with 1/8” masonite strips on the female mould sides and the bit protruding 1/8” below the wood. Quick, easy, simple. I did relieve the X-braces at the waist to permit an easier bend, but don't know how this will affect the sound.

As I had trouble on guitar #2 bandsawing the rough neck with my screwdriver headstock (wider than the neck) attached, I'm going to attach it this time after bandsawing in the plan and elevation faces. Liked the simple bandsaw version of a Spanish V joint to attach the headstock and intend to keep using it, until one breaks.



Building the body is pretty much simple carpentry, though I'll admit to putting on my machinist & mechanical designer hat for a couple minutes on the neck design, actually having to resort to simple math calculations at a couple points.

I wanted to use the old Martin 3/8” square tubing kind of non-adjustable neck reinforcement, but when I got to Alro Steel's retail “odds n ends” store in Jackson, the smallest square tubing they stock was 1/2” so took John Link and David Russell Young's advice and bought a 3 ft piece of 1/4” x 1/2” mild steel, sheared, not ground. Since I'm a zero-scrap designer, this will provide 3-12” pieces, and John advised to let it fall short on the nut end.

It's obvious that it's counter-productive to build one guitar at a time. A minimum of two would be more efficient, with larger numbers exponentially more so. That would require more moulds, however, and the time/money/effort to design efficient time-saving production jigs and fixtures. Then again, I will have a second granddaughter born this coming October, and I may just be “Gone to Texas” for a while.

I may also yet arrive at using actual tone-wood soundboards. I have a splendidly quarter-sawn piece of old white oak, split on one end but maybe long enough to do sides and back of a parlor size 0 12-fret guitar, and I'd like to build an Orchestra Model with deeper body, at some point. But #4 is going to be is identical to #3 except ladder-braced. Lots of old bluesmen played more splendid music than I'm capable of on some of those.

This is an interesting approach Will. I just don't see the "stupidity" you cite. You have excellent control over what you are doing. Keep up the pix.

Nothing stupid about exercising the brain and having fun some at the same time! I really like that "true volute" headstock attachment, been trying to figure a good (efficient) way to make necks like that. Not sure many know that the Martinish volute was a well thought out construction feature and more than just a decoration.

Ken,

Appreciate the kind words. There's a site that explains the V-joint well at:
http://www.mandolincafe.com/forum/showt ... sh-V-Joint

We luthiers - I presume to use the term luthier, since I'm far from being one - tend to call that lump produced by making a Spanish V joint a volute, but any architect or even an old stair carpenter will tell us that we're using an incorrect name, for a volute is actually a spiral. Several makes of current guitars program this "volute" into the tool path for their 5-axis mills as an apparent stylistic element reminiscent of the old Spanish construction methods, when in fact their necks and headstocks are all one piece.

These joints are amazingly tolerant of less-than-perfect fits, and aliphatic resin glue works fine. Since I was a working carpenter before I taught Shop or did mechanical design for a living, my fixtures tend to be quick and dirty. Photos attached of my gluing fixture, and a piece of railroad iron hung from my #2 guitar headstock. For gluing, at the top of the headstock are two dark wedges crosswise, driving the headstock down on the neck. My joint is 1" wide and 1-1/2" long.

Regards, Will

The Spanish V joint site mentioned above seems to have gone away. Try this one: http://marfioneguitars.com/lacote-v-neck-joint/

I rushed the neck for guitar #2, wanting to get it done for Christmas. It's way too chubby, like holding a baseball bat. So far guitar #3 is coming along at least an order of magnitude improved, and if it plays when complete, I'll go back and rework the neck of #2.

I made a fixture (photos) to taper the bottom of the neck for guitar #3, getting thinner at the nut end. There may be better ways to do this but this was quick. The nut end props up on a piece of 1/8" Masonite, and a wedge retains the neck. Fixture sits on the table of my radial arm saw with a dado head in place of a saw blade. I cut it a little high, as the cut of my dado head isn't perfect, but a plane cleans it up nice. As the headstock interferes with the bottom of the saw motor, you cut half way and then reverse the fixture on the table.

Next step will be to attach the fingerboard and use a router bit with bearing above it to trim the sides flush with the fingerboard as it can be used as the guide for the pilot bearing.

Made a fixture from a 2x4 to hold the neck while it gets shaped. I took a square file and filed a "vintage neck" profile at frets one and nine. Then I rasped and filed from fret one toward the headstock and from fret 9 toward the heel, for rough shape. Now I'm planing from fret 9 to fret 1.

I'm a 3-D form guy. I understand line, form, contour, mass, and volume but this is still tedious, since the final form of the neck contributes greatly to whether or not the guitar is comfortable to play. It's a tactile process. One should take the neck out of the form lots of times and run hands on it. I understand why the "big-times" use 5-axis mills to do this.

I don't need to rush this one to get it done by Christmas, so work at it only when I feel like it and in the meanwhile, I've got sides, blocks and linings in my female form for guitar #4, to be same form and materials but ladder-braced, so I can maybe hear the difference in sound, if any, between X and ladder bracing.

Very interesting work, especially the v-joint. I have been meaning to try one on one of my classical guitars but have been a little nervous to try.