The bracing layout is in pencil, once the rosette is installed and soundhole cut
What a busy week! With 9 hours per day spent between lecture and shop time, we have our hands full with our building schedule. While we do have the benefit of jigs set up for certain tasks, such as sanding a radius into brace stock, otherwise we spend a bulk of our time learning how to carefully attach small pieces of wood together, then elegantly carving away much of the material we’ve just attached. What remains is the guitar.
The bracing of the top is a great part of the artistry of guitar making and design. You would think that the soundboards of a guitar would be made flat and strong, right? What isn’t apparent when looking at a fine guitar, is how it has been engineered to withstand the constant pressure of the strings, not to mention made to sound good when played.
Flat to the untrained eye, the top (front, usually light-colored spruce), top braces (the sculptural reinforcement glued to the underside of the top, mostly hidden from view), back, and back braces are a much more complex system than first meets the eye. Modern guitars are built “under tension”, meaning that the top and back plates (the major sources of sound from the instrument) are forced into a subtle arch during construction.
The plates are first sanded flat and fairly thin. Next, the sturdy spruce braces that are to be glued inside are given a radius usually between 15′ and 25′. When glued to the top and back, these braces induce arch into the thin plates. This creates a stronger and more resonant structure. It is also a fair amount of work.
One of the wonderful clamping tools we use in the shop is called the Go-Bar Deck. The deck consists of two plywood plates held about four feet apart; the assembly to to clamped faces upward, and flexible shafts are bowed between the part being glued and the upper plate. This allows one full access for glue cleanup, fine control over clamping pressure, and and inexpensive alternative to using deep-throat clamps. Best of all, it looks way cool.
Once the braces are attached with hot hide glue, they are profiled and scalloped prior to final voicing. This is a major contribution to the fine, nuanced sound of a hand-built guitar. For a first-timer, it is also laborious and time-consuming. The 1930’s Gibson design I’m using has 14 bracing components. Each has a purpose, and each must be precisely fitted and shaped for the best result.
Meanwhile, back I’m listening to old reggae favorites and having nightmares about my chisels not being sharp enough. In other news, I’ll be taking a trip down to visit friends in Viroqua, Wisconsin this coming weekend. While I’m down there, I’ll be participating in a wonderful radio show sunday evening. Styled after the great old-time radio barndance programs of the 1930s, the Driftless Radio Barndance is loving variety show played live in a gorgeous tobacco wharehouse-turned-bookstore in Viroqua. You can expect some fiddle music, some fine country harmonies, and plenty more. You can listen in live streaming around 7pm this Sunday February 3rd, 2013.
And what is possibly the most beautiful book store in the whole world:
http://www.driftlessbooks.com/
Chris Miller Guitars 
pretty impressive. the one photo looks like the exhibit at the S.F. Museum of a dinosaur and his ribs! Pretty cool. A lot of work.
I have an original Roy Smeck Radio Grande from 1935 that is probably the best sounding acoustic guitar I’ve ever played (and I’ve played many fine vintage instruments). i wanted to mention that on most of the Radio Grande models, the braces are *not* scalloped. Mine is this way, and it sounds huge — loud but very well balanced, especially for such a large guitar. So you might want to see what it sounds like before you start scraping away!
Hi Al,
You caught me!
Since I first planned the build, I’ve learned more about the Smeck models, and I realize that it would be inaccurate to claim heritage. I’ll be the first to admit that it’s not a faithful copy. The guitar is a slope-shouldered dreadnought, 12 frets-to-body, with a 24.625″ scale length and an 1 3/4″ nut. The bracing is patterned from plans drawn up by my instructor; it is a combination of the 1930s Gibson guitars that he has measured. They were scalloped during voicing to achieve a nice chorus of “tap tones”. I’ll be very interested to try another without scalloped bracing.
Thanks for letting me know about your Radio Grande. If you have a chance, I’d love to see some pictures and/or hear some recordings of your guitar! I’ve not had the pleasure of examining one in person.
Thanks,
Chris Miller
Hi Chris, The thing that makes the Smeck guitars unique compared to Gibson’s other flatops of the 30s and 40s is the size of the box joining at the 12th fret, and the slightly smaller sound hole, which allows some balance — unlike many dreadnaughts such as D-28s J-45s, etc, the Roy Smeck models are never boomy or muddy in the bass, which is one reason they are prized. Even though my Radio Grande has the huge box with the shorter 24.6 scale, it remains clear in every register. Another thing to note is that the back and top of these guitars remain parallel from the butt to the heel, there is no tapering of the body, the sides are the same width from heel to bottom. With a guitar this large, the tone bars probably would not need to be shaved too much. Otherwise what tends to happen is that the guitar can become almost too live and harder to control. Also the heavier bracing can make for a more powerful sound. Of course there are many other factors, such as thickness of the top, what type of spruce is used (should be red “Adirondack” spruce if possible) and so on. If you send me your email address I’d be happy to send you some photos of the guitar. I can’t send a sound sample right now as my Radio Grande is in the shop for some neck work at the moment. I should have it back in a few weeks however. My email is akaatz AT gmail DOT com.