Posted on June 6, 2024May 27, 2025 by Dale Phillips Questions: Guitar Rib Depth Questions: Guitar Rib Depth by R.M. Mottola Originally published in American Lutherie #85, 2006 Mark Korsten of Hastings-on-Hudson, NY asks: The article concerning how the rib depth of guitars should be adjusted when plates are domed was clearly written and illustrated (AL#84). I truly appreciate the insights offered by author R.M. Mottola. Being a neophyte luthier, however, I have what is probably a naive question. How does changing the depth of the guitar’s ribs modify the manner in which the bindings are fitted to the binding ledge? It’s a fairly easy operation to bend the binding when the plates are flat. However, when the depth of the ribs are varied, doesn’t that introduce another plane to the geometry? Do you simply use more flexible, thinner bindings or stronger binding tape to keep things tightly apposed in the ledge? R.M. Mottola responds: Although the doming of the plates means that the side depth of the ribs must be varied so the ribs and plates can be glued, this type of construction has little effect on binding. The ledges can be routed using a router resting on the plate or inverted in a router table. In either case the doming is so slight that the routing can be done just as if the plates were flat. And although the bindings must be bent vertically to accommodate the varying rib depth, the amount is so small as to be inconsequential. ◆
Posted on June 6, 2024January 17, 2025 by Dale Phillips Letter: Side Soundhole Guitar Letter: Side Soundhole Guitar by Marc Connelly Originally published in American Lutherie #93, 2008 Dear GAL Family, Thank you Cyndy Burton for the exploration of side-ported instruments. It was a terrific affirmation for this most interesting fenestration option. Like Mr. Montelone, at some point I laid my head on the side of my old Martin, strummed, and wondered how to get more of that big wood and bronze sound into my face. I started experimenting with a “side hole” variant, and it changed the way I think about what I am doing — not because it was “better,” but because it was clearly different in a thought-provoking way. In fact, this exercise has finally purged the word “better” from my lutherie vocabulary, and that’s a good thing. My side-hole instruments (which I call “Atlas”) are from the same plantilla as my front-hole models, so I can make some general comparisons. At first, the Atlas models seemed a bit too percussive and weighted toward the bass. So I made some small modifications in the way I tune the box and tamed the bass. The percussive nature of these guitars is simply a component of getting a more direct blast of wavy air into the player’s face. I have come to like this. Several Atlas owners have agreed it has an appeal and have readily adapted to it. But a truly freakazoid experience is to stick your left ear in the hole and play! There isn’t a prewar D-45 on the planet that sounds like that! Until I read Montelone’s article, I never even considered the possibility of weakening the side. What was I (not) thinking! None have folded up, but future Atlas models will have some consideration for this possibility. Fusion jazz player Don Mock owns an Atlas and loves it. Don enjoys having people ask “What’s that?!” Of the folks who play my guitars with some interest in commissioning one, the Atlas is always the first off the rack. But guitar players are an amazingly conservative lot, I find. Selling a side-hole guitar is like selling a blonde guitar. You are either open to them or you are not. It is personally rewarding to watch the tug of war between the conventional and the unconventional. ◆ Photo by Marc Connelly.
Posted on June 6, 2024May 27, 2025 by Dale Phillips Questions: 17″ Scale Length String Questions: 17" Scale Length String by R.M. Mottola Originally published in American Lutherie #87, 2006 Rob E. of Lexington, MA asks: Does anyone know of a string that can be put on a 17" scale length instrument, with an after length to the tailpiece of about 6", that is strong enough to reach a mandolin E tuning without breaking? “Questions” editor R.M. Mottola answers: A string with a small enough diameter to be tuned to this pitch at this scale length will have a breaking tension that is too close to its static tension to be of much practical use. When specifying the scale length for a new type of instrument, use a length similar to that used by existing designs with the same pitch range. For high-pitched instruments with long scales (such as the instrument in question) the issue is finding a string with high enough breaking tension to be useful. Unfortunately there are no simple solutions short of having strings custom-made of high-tensile-strength materials. For low-pitched instruments with short scale lengths the issues are tone and, for fretted instruments, intonation. Short, fat bass strings don’t behave much like ideal strings and their partials tend to skew way sharp as they are further shortened by fretting. There is a mathematical relationship among scale length, pitch, tension, and mass per unit length of a vibrating string. Download the paper entitled “Catalog Supplement / String Tension Specifications” from the D’Addario website. The paper (in PDF format) can be found at www.daddariostrings.com/Resources/JDCDAD/images/tension_chart.pdf. It contains comprehensive info on the string formulae as well as mass-per-unit-length (unit weight) data for every string D’Addario makes. Unfortunately, breaking strength data is not available in this paper as the issue of specifying the tension at which a real string will break is more complicated than it might appear. Tensile strength data is available from wire manufacturers but the best bet is to design high-pitched instruments using short enough scale lengths.
Posted on June 6, 2024May 22, 2025 by Dale Phillips Letter: Kenny Hill Responses in AL#98 Letter: Kenny Hill Responses in AL#98 by Alan Carruth Originally published in American Lutherie #100, 2009 Tim — I found Kenny Hill’s response (in AL#98) to R.M. Motolla’s study of ports (in AL#96) interesting. I’m not going to answer every point he made; some are more properly addressed by R.M. himself. However, there are a couple of things I would like to comment on. Kenny wrote: “I’m guessing that Al’s cool Corker was not really constructed as a concert instrument, that it does a good job at its original intended purpose but was not built to prove or disprove the validity of soundports as a useful design element.” I think the concept of what is or is not a “concert instrument” is slippery enough that we won’t settle it here. Nobody is likely to appear on the stage with something as rough as the “corker” so that in itself excludes it from that class. I will note, though, that several people, including one very fine maker, have remarked that it is at least “not bad”, and R.M. told me that most of the players had a much higher opinion of it when they were blindfolded. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on June 6, 2024May 23, 2025 by Dale Phillips Questions: Scale Length Questions: Scale Length by R.M. Mottola and Tim Olsen Originally published in American Lutherie #93, 2008 Byron from the Internet asks: Is there any way to determine the scale length of an instrument from a piece of the fingerboard? I have the fingerboard from an instrument that is currently being restored. The nut end had been trimmed, I think to accommodate some kind of odd nut. The Questions column editor responds: All inter-fret distances are related to scale length, so measuring, say, the distance between the 1st and 2nd fret and then looking that up on a fret scale chart will tell you the scale length. Or measure the distance between the 7th and 19th fret (assuming the instrument has a 19th fret of course) and multiply by three. The result will be within a few hundredths of the actual scale length, close enough to identify it. American Lutherie editor Tim Olsen responds: Imagine you put a capo on the 1st fret of a functional guitar. Measure from the 1st fret (now functioning as the nut) to the 13th (now functioning as the 12th), and double that to find the mathematical bridge point. If the fretboard is still on the guitar, you can find that point near the saddle and mark it. If the fretboard is not on the guitar, you can clamp it to something, like a 2×4, and mark the bridge point on that. Now you could easily find the nut point by measuring from the newly marked bridge point back to the 12th and doubling it. Confirm it by calculating the scale and checking the position of the individual frets. ◆
