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       July 21-26, 2013            Oct. 20-25, 2013

We attended the California Bluegrass Association's "Father's Day Bluegrass Festival," which is held in Grass Valley, California during the whole week leading up to Father's Day. This one of the largest festivals in the U.S. and features great bands, endless jamming, terrific camping under the ponderosa pines, and an all around excellent week. Each year, we have a booth in the "Luthier's Pavilion" were we have the opportunity to catch up with many good friends and customers, present a few workshops, and get to see a lot of great instruments that customers have made from our kits and parts. After the festival ended, Kali, Amy, Ken, and Nolan headed back to the shop, and Rosemary and I took a much needed break and headed out with our dog and our trailer to several mid-West locations. (At the moment, I am writing this month's newsletter from a campsite in Huron, South Dakota.)

Our first stop was in Ohio, and from there we headed north to Kalamazoo, Michigan to have lunch with my dear friend Jim Deuloo, who was the former plant manager of Gibson before the company moved to Nashville in 1985. While there had the chance to revisit the original Gibson factory building where I spent many years working as a consultant.

It was great going back to the "old building" where so many wonderful instruments were created and produced. Built in 1917, this three-story building now occupies several companies, including Heritage Guitars which utilizes the entire ground floor. Heritage was founded by three former Gibson employees: Jim Deurloo, Marv Lamb, and JP Moats, and they were later joined by former Gibson employee Bill Page. These guys make a beautiful line of guitars and unquestionably, they have the talent, experience, and knowledge to build them right. And, they are doing it in a place where incredible people worked, and where equally incredible instruments were produced over the years.

For those of you interested in Gibson and Loar history, the well known photo of Loar standing at a workbench was taken in the room behind the middle set of windows on the right, just over the bushes.

Standing as a sentinel over the old building is the historic "Gibson" chimney that was struck by lightning several years ago and is in serious need of repair. If you look at it carefully, you will see that is leaning to the right at a point beginning with the "I" in Gibson. In the coming months, I'll be sharing ideas with you about a program I hope to launch to save this vital landmark and ensure its longevity. Please watch for it.

There's a lot of history in this building. It's a magical place where the spirit of incredible luthierie still resides. Even on a quiet Saturday - with no one inside the building - one can still feel the buzz.

And one more thing...A good part of my day is spent responding to a wide variety of questions about luthierie; some of which are not directly related to our product line or services.

Several of us here thought it might be valuable to share these questions and answers with you in the hope it would broaden your experiences. So, with this in mind, I'm pleased to present our first Q & A: Readers Ask column (see below). I won't mention names so you'll feel more comfortable when you communicate with me. Don't hesitate to direct your questions to me.

 

In our last newsletter, I spoke about backboards and what their contribution is to the instrument's tone. (If you didn't get a copy of that issue, please email me and I'll send you one.) The soundboard is the heart of the instrument whose pulsations are driven by the strings' energy. The soundboard's movements control how the tone will be shaped and to what level the amplitude can be driven. A stiff, dense soundboard provides a poor, thin tone with minimal amplitude, and a supple soundboard provides a warm, rich tone with significant amplitude. Controlling the density and graduations of the soundboard, and managing the stiffness (tuning) via its tone bars and braces is the secret to creating soundboards that produce excellent tone.

Light, strong, supple woods are typically chosen for mandolin and mandola soundboards. While the common preferences are Sitka spruce (Picea sitchensis), Red spruce (Picea rubrum), and Engelmann spruce (Picea englemanni), many other softwoods can be highly successful as soundboards. Among these are Western red cedar (Thuja plicata), and California redwood (Sequoia sempervirens). These last two offer great warmth and richness and are excellent soundboard choices. Their only downfall is that they are a bit more delicate than their spruce counterparts and have to be handled a bit more carefully during construction (however, once assembled and supported by the rim and tone bars, they provide good longevity). Careful attention should be paid to sanding redwood and cedar; they sand so easily that their thickness and graduations can thinned more rapidly than expected. Another choice that many builders like is Douglas fir (Pseudotsuga menziesii). Douglas fir is denser than its spruce counterparts and provides a driving bright sound.

Occasionally we find good clean pieces of close-grain pine; while this is not a wood we sell because of the non-abundant supply of clear pine, it is certainly something you could consider trying. The following chart provides some guidelines as to the tonal properties of the popular soundboard woods:
Of course, the soundboard by itself does very little. Were it not connected to an enclosed air chamber to create the necessary compression and rarefaction, the soundboard in and of itself would be useless.

A graduated soundboard - one that is thicker in the center than it is along its perimeter - provides the functionality of allowing the centermost portion of the soundboard to move as a unit, flexing against its thinner outer region. As greater power is applied to the soundboard via the bridge, more of the thinner outer region can flex, and this centralized control of the soundboard's movement is one of the key features of a graduated plate. As a result of graduation, whether played lightly or intensely, the properly graduated soundboard works as a unit.

Typical Dreadnaught-style guitars feature soundboards that are completely flat (some makers thin their soundboards in the last 2˝ or so where the soundboard meets the rim). In addition to providing structural integrity to the guitar's soundboard, X-bracing provides the benefit of making the soundboard stiffer in the center than it is around its perimeter - an attribute similar to a graduated soundboard.

The arched and graduated soundboards on F5 style mandolins and H5 style mandolas feature longitudinal tone bars that run the length of the soundboard and are typically positioned asymmetrically. The advantage of asymmetrical tone bars is that tone bars placed near the center of a soundboard raise the pitch of that portion of the soundboard. As tone bars are moved further outboard, the pitch of the soundboard is lowered.

Some makers have used X-bracing on the arched and graduated soundboards of their mandolins. In my mind, X bracing on a graduated mandolin or mandola soundboard is a conflict of purpose and functionality. Since the soundboard is already thicker in the center, building a stiffer center with X-bracing is counter to the purpose of graduating the soundboard in the first place. Secondly, one main benefit of longitudinal tone bars is that each of the instrument's two bridge feet sit over a tone bar. In the X-brace design, the bridge feet sit over gaps in the X.

Tone bars help to tune the soundboard, and in the case of the traditional steel string acoustic guitar, tone bars are used to control the vibrational modes of large un-supported areas of the soundboard (such as the region between the bridge and the butt of the instrument). Braces are for structure.

Next to selecting the right materials and ensuring that all parts are shaped and crafted properly, a key focus for the luthier is assuring that all parts are perfectly aligned and joined. The task may see rather simple, but clamping parts that have glue between them is akin to standing on roller skates.

The ideal thing to do is use of some form of locating pins or dowels to keep the parts aligned as the clamps are tightened. Most instrument manufacturers who produce quantities of like kinds of instruments will use wood dowels as locating pins. Wood dowels are perfect for the purpose, but they do require the accurate drilling of the recessed holes into which the dowels are to be set. More importantly, the recesses in the two parts to be attached must be in the exact relative locations.

The majority of private luthiers don't have the resources to set up multi-spindle drill presses and fixture them so that locating holes can be perfectly drilled in complimentary locations. For most of us, some other form of alignment tools is necessary.

Over the years, I've found it much easier to use small round-head nails as locating pins (featured in the Products section above) and place them where needed in the parts to be attached. With the locating pins installed in one part, I can align the other part where it needs to go and tap gently on it to transfer a small dent from the head of the nail in the reverse side of the to-be-attached piece. Then I simply drill a small recess into the dent I made on the part being aligned to accept the head of the nail. The end result is having the locating pins in place in one part, and two locating holes in their exact location in the other part.

As shown in this photo, I use these locating pins to help align soundboards and backboards before gluing. And I find them absolutely vital when gluing fretboards to necks. The pins are small enough to not interfere with repairs when soundboarfds, backboards, or fretboards have to be removed.

One great benefit of using these round head locating pins is that they can be moved slightly to make minor alignment corrections. Simply place a screwdriver against the head of the nail, and tap the screwdriver with a small hammer to move the head in the direction it needs to go to adjust the alignment.

Another benefit is that the tapered shank seats firmly in the required 1/16" hole and this provides for a snug, life-long, and buzz-free connection of the locating pins.

Q: Why does the body have to be assembled before tap tuning can be done? Why can't you tap tune just the soundboard or backboard off the instrument?

A: Actually, you can tap tune them off of the instrument, but it has been our practice to tune the soundboard once it is attached to the ribs (rim). The primary reason for doing this is that a soundboard perforated with f-holes (which we prepare before we attach the soundboard to the ribs) vibrates in many modes which makes it difficult to clearly measure the frequency of the soundboard and its tone bars. Once the soundboard is anchored to the ribs, the soundboard's modes are constrained and the frequencies are much easier to detect. Since the backboard does not have f-holes, we can easily tune it separate from the instrument.

Have a question? Be sure to send it in and we'll answer it in an upcoming issue. Remember, we won't post your name, and chances are, if you have a question, someone else probably needs the same answer!