Making the Selmer Guitar II

Call me Selmer
-Some time ago- never mind how long- With a particular interest in this design and little to no money in my purse. I began to explore the parts of this instrument; as a way to shake off the sawdust and regulate the circulation. I’m a stickybeak, or I strive to be. As I ferret through these dregs, my viewpoint will ramble. Compelled to reinvent my method, needed or not, as I seek the answers to questions unasked. Unafraid knock the backs of heads; usually, to my detriment, as I strive to tell this parable. Only immersed in these fragmented mediums do I find relief. If I’m lucky, you’ll find me humorous, if not merely irritating. I’m going to keep it up; until I get it down. You may ask, What is the point? This work in my estimation is at its nucleus creative. You may not find CNC milling a replica of an instrument originally produced from 1932 to 1950 in France, a creative act. I intend to persuade you otherwise.

I have developed an appreciation for Django Reinhardt’s music. It sprawls in an unusual void between folk tradition and modern technical music; It encompasses virtuosic elements and distinctive syncopated cadences. The tone of this unique sound, virtuosity, and syncopated thump arises from this intriguing implement. My Interest in this apparatus is only natural. I find this design and process indicative of an extraordinary time; the Art déco look is just as intriguing today. My attempt is not a meticulous replica; it’s more like a highly influenced study. A reconstruction using modern methods. You’re free to hitch a ride, I won’t guarantee any wisdom as this narrative unravels. I hope it is, at a minimum, an interesting journey.

I planned to include the Fusion 360 file for this build with complete CAD and CAM for the entire process. Unfortunately, it’s over the upload limit size. I share all of my YouTube channel build files on with my patrons and I will include the link here. There is only one level to contribute at $1 per month. I have posted Fusion 360 files for quite a few instruments there, and I add new files as I complete each series on YouTube. So far the list includes a Gretsch White Falcon, Stradivarius B-form Cello, Jazz Bass, Gibson Explorer Ken Lawrance, The Bee-Style Mandolin, A5 Mandolin, Selmer Guitar, ES-335 1958 Fat Neck, Guarneri del Gesu Vieuxtemps Violin, Tenor Nyckelharpa, and the Archtop Mandolin.

https://www.patreon.com/Twocherriesinstruments

I try to make things easier on myself as I aim broadly at wisdom. I enjoy making tools -and in a way- the product of this labor is simply put, a tool for the musician. Craftsmanship is a collection of skill sets developed through application. What we learn from this process allows us to define a strategy and improve. There is no doubt in my mind that the original makers of these instruments crafted many of their own unique jigs and fixtures. My process may be slightly different, but the aim is at a comparable target. The first of these is the side bending jig. I’m sure you’ve seen some beautify constructed side bend jigs online, and If you’re planning to make this pattern many times over, then absolutely make them out of something that will last. My fancies wander; I rarely make two of a design. On top of it all, I’m what the chic among you call frugal, the rest cheap. The least expensive material to use is MDF. It won’t last forever, but they hold up well. If MDF glue joints are tight, they make excellent jigs. I’ll go into more detail about how to use this jig in Step 3. I enjoy the accuracy that the CNC provides, especially for jigs and fixtures. I will rely heavily on the CNC throughout this build. You can certainly do all this work by hand; This is an attempting to use the CNC not as a production tool but as a method to increase accuracy. I understand some folks will object to these methods. I think they speak to the intent of this instrument and time uniquely. Art déco is a mixture of classical and modern elements, just as this instrument is a mixture of building techniques. I like to think that these elements complement each other. While I’m sure some will disagree, lets continue and pay no head to these decenter’s. If they wish to use the files offered to build their own without the aid mechanization, they are quite welcome.

I think everyone is seeing the significant amount of work in making the jigs and fixtures. There are 49 different CNC setups in this build. The immense amount of work 3D modeling the instrument is unmistakable. I construct the outside mold similarly to the bending jig. The back is not parallel to the top; this makes the sides challenging to shape. There are a couple of ways to achieve this; I created a mold that reflects this shape. This nifty bit of milling ended up making the work easy. To add insult to injury, if you will pardon the cliche; The kerfed linings are CNC milled. At the time I was getting a lot of criticism for using the CNC on my violin project, so this attempt not only kills two birds but also takes a sarcastic cuff at my dissenters.

I use Spanish cedar for linings. It’s not in any way necessary. We rarely talk about the sense of smell when making guitars. It brings about fond memories of my local guitar shop. I’m compelled to use it in my instruments. I encourage you to take a deep sniff of the sound-hole. Take no notice of the strange looks; it’s perfectly normal to shove your beak in there and take a whiff. Behind the art déco design, the extraordinary music, and unique tone, there is yet another empirical grade to this endeavor. I also CNC mill the neck and corner blocks. They are simple parts and the milling is not all that impressive It’s just a chunk of wood with a little bid of contour to match the inside of the ribs. We will need these blocks in the next step as we fit the sides into the molds and clamp and glue in the blocks and then the kerfing.

I am endlessly captivated by this technique. This material is dynamic, it behaves in unique ways. It’s elemental to the human condition to produce tools, decorations, anything really out of this fascinating substrate. The combination of heat, moisture, and timber spark interest. Unlike the first build, I will use a much easier method to bend the sides. It may seem like I have taken all creativity and skill from this task. I would urge you to undertake this work manually in the beginning. The lessons learned will translate. I don’t want to replace the skill of manual bending, only improve its accuracy and repeatability. A great deal of thought goes into designing these forms and jigs, only those who have learned from experience will benefit from these adaptations.

I spray the thicknessed sides with water. It’s essential to have enough water to generate steam, but not overdone. I wrap the side in aluminum foil. It’s not the heat or moisture alone that convinces the wood fibers to slip; the secret is steam. If you can hold steam in proximity to wood, it will deform easily. I sandwich this envelope in flashing to support the fibers as they curve. I use a heating blanket to provide the heat. There are complex controllers that precisely control temperature. I like to keep it simple. I plug it in; the heat generates steam, and the wood will bend slowly and carefully. When completed, I unplug the heating blanket. I cycle the heat a few times to remove moisture and set the bend. I clamp the bent sides into the mold to help them hold their shape. There is just as much room for error in this method as in traditional bending. The same skill and experience guide success in both. while the results are far more constant. This accuracy makes the work extremely fascinating. I absolutely enjoy setting up and executing this work. It’s not as easy as you imagine, but with a little experience you will enjoy is as much as I do.

When faced with a problem, It’s good to let your mind wander. Sometimes an idea floats in and changes your approach. This one is a little out there, and I wasn’t sure it would work. I have satisfied due diligence in warning you that things would be done differently. This process, while not perfect, taught me a lot. I milled the braces on a jig. The top contour of this instrument is not a straightforward radius; It’s a contour like arch-top guitars. If I shape the braces to this contour and create a die to hold the top and braces together, I can recreate this shape precisely. It’s a marked departure from typical methods. I’m pleased with the results and I have a few ideas to improve it in the future.

I created a jig to hold all the brace material in place, and I used masking tape and CA glue to the braces to the jig. I didn’t pay as much attention to detail as I should have, and If I had to do it again, I would have built the jig differently. It thrilled me to see how these carved braces shaped the top. I plan to improve this process in the future. This method is due further exploration. It wouldn’t be possible without the CNC. If you allow it, technology can inspire us to explore ideas that previously would be far too complex and detailed to execute.

Like it or not, instruments have to look good. I call it functional sculpture. These things have to sound great, function properly, and yes, appearances count. There is not very much functional about this decoration. It does aid in keeping cracks from forming at the sound hole; beyond that, it’s purely a visual element. I cut out the cavity with the CNC and inlay the purfling strips. I mill the key-block fit and glued it in; I can then scrape and sand the rosette inlay flush with the top. I don’t feel as if I need to draw any conclusions to the artistry and creativity in this element, It’s plainly obvious. It also seems clear that the CNC makes clean, efficient work of this design element.

The devil is in the details. These small things rarely garner enough recognition. This departure from the norm is interesting to me. Usually guitars have a unique contour at or behind the bridge, known as a pliage. I’m not fond of this geometric oddity. It doesn’t seem to fit with the classical art deco look and feel. This instrument is like arch-top instruments. Radius dishes form the slight arches of dreadnought guitars. The pliage and brace shape from Selmer tops. I thought it would interesting to organize these processes uniquely. We previously shaped the braces to this custom top contour. Now I need a die of the same shape to support the top as I glue in the braces; forming the top contour. So I made yet another jig. The CNC makes quick and accurate work of this job. I glued in the braces using a go-bar deck; It couldn’t be easier. I hope to experiment more with this process; I think it should be relatively easy to form more complex geometries using this method.

Tone is primarily a preference. We each, in our own way, take delight in small tonal variances. Minor adjustments can both please and irritate us. There is no perfect thickness or shape. I have created a few acoustic instruments, I only possess a small understanding of these complex intricacies, learned through trial and error. The basic idea is to remove mass from the bracing and allow the top to resonate sympathetically. No two pieces of wood are equal in mass, strength, rigidity, or resonance. There are many ways to approach this imprecise process. The method most luthiers use is tap tuning. I like to tap near the bridge, not to replicate a specific pitch, but to test how sustained the resonance is. The sides will restrict the top and back further when they come together. It’s a good idea to keep that in mind. Great sounding instruments are under-built, they sound fantastic but will not stand the test of time. Overbuilt instruments will last a very long time, but diminish tone and volume. It’s our job to thread this needle in a way that balances durability and tone. You need to keep enough brace material to support the top and string tension of the instrument, while removing adequate mass for the top to speak naturally. I learn more with each instrument. Start with traditional dimensions and experiment to get the results that define your unique tone.

The complicated design work and meticulously crafted fixtures and jigs pay off. As things take shape, the work gets more interesting. The drive to completion accelerates. The contours fit into their places and define this ornate box. This machine, a fascist killing, air pumping, resonant chamber readies to preform its intended task. I cut notches into the ribs to fit braces, and I attach the top. The mold made for shaping the top supports the structure as it’s fixed, and as I coax the rib structure into shape. Ribs and braced top work together to form a rugged frame. Individually each part is flimsy; together, each reinforces the other’s weaknesses. The first taps establish the resonant capability, now reinforced. I follow the same procedure to attach the back. Marking the positions of the braces and notching the ribs. I support the back with the contoured mold while clamping to close the box. Then I remove overlapping joints of the top and back, and I cut binding channels. I tape binding into position and attached it to the box by wicking acetone into the seam. The acetone softens the binding and adheres to it to the body. Then I scrape and sand away the extra binding material. The completed box is always a wonder, the satisfaction of the form and work bring a slight pause to the fury of forward momentum. It’s a practice that many of us undertake, this time looking and feeling the completed shape is the calm before the storm of the incredibly challenging work to come.

The only way to get good at it is to make a lot of them. I carved many by hand before the CNC. I still do a considerable amount of finish carving by hand; The reason is simple. I like to leave extra material around the neck contours. When the fret boards attached, the back of the neck, heel, and head stock transition are shaped simultaneously. Creating a natural flow and feel to the part.

The way I work may not be the most efficient, and that’s OK. I’m trying to make precise parts. Production speed is not my goal. Take your time and do the job right the first time. It takes a lot less energy and is more satisfying, not to mention faster. I thickness sand the stock required in the Fusion360 setup. I run it through the joiner on one edge. this creates three accurate surfaces to indicate from. I roughly cut the scarf joint on the band saw and set up the stock up to mill the scarf joint on the CNC with a 3/4" ball mill. I finish the surface by hand before the glue-up. Because the scarf joint faces are CNC milled with the lumber on access, I can recreate precise angles. I have learned to be patient with these gluing procedures. It takes some experience to know how much glue to use and how long to wait for the tack. I get better at these with each attempt. You might notice the use of salt to help keep the faces from sliding under claiming pressure. I have abandoned this practice. It’s a more reliable joint if you give the glue a few minutes to tack before applying full clamping pressure. The overhang on the joint is intentional. I mill off the extra to create a perfect scarf angle and parallel peg-head face. Then I attach the peg-head veneer and manually remove the excess. I won’t go into all the details of my milling procedure. Refer to 4:17 in the video for this explanation.

This process is frustrating, and more than once, I have ripped a failed milling operation from the spoil board and tested its rebound capacities off of a shop wall. If you want to become proficient, you are going to need to fail. Keep at it, and it will become easier. I learn with each attempt. I milled this neck over six months ago, and I have learned a lot about this process since. In the end, the journey is far more interesting than the result.

Haste is sharp; it’s a trap triggered to severe to the fool from his creation. Things get intense. The amount of work on destructions’ doorstep is slapstick. Imagine clamping a week’s work under a set of 20,000 RPM rotating carbide teeth; one nibble consuming day’s of labor. I‘ve discovered more effective ways to achieve this task, and with them, my confidence has grown so that I am now only half as timid. First, I secure the neck close to vertical; The neck angle is calculated in Fusion360 and the vertical jig is set to match. I mill the heel with a facing operation to this angle before cutting the tenon. The tenon is milled first with a rouging pass and then a series of finishing passes. Milling the mortice puts any stress involved in the tenon scheme to shame. I mill the mortice pocket in the same way and then step out the pocket by 0.005" to achieve a friction fit. I cut the fretboard inlay from a piece of Bubinga. The contrast between the deep richness of the Bubinga and the dark ebony looks amazing. With the fretboard inlaid, I cut the radius using a scallop tool path and a 0.75" ball nose bit. I mill fret slots with a 0.024" bit on a tool path that follows the contour of the fretboard radius leaving a contoured slot. There is some work to fit the mortice and tenon of the neck joint together, done by hand. Once everything is dry fit and properly aligned, I glue the neck into position and the instrument takes another step closer to becoming playable.

With obstacles lined up waiting as we drive toward the moment. Parts come together in a gratifying course. Knowing where each piece belongs and how we form each is only on the piece of the puzzle. Odds and ends, petty parts, and minor details. The taped tone and body resonance are a driving force. Completions seems in sight and yet daunting in minute details. The truss rod is an odd length and requires customization. The frets installed, leveled, crowned, and beveled; and the bridge is milled and fitted.

The enormity of a project like this one settles in as you get ready to make the final conversation. Just parts glued together and shaped. Not until it’s strung up and we strike the first note, do we have any way to contemplate the tonal qualities. It becomes an instrument. All the pieces have come together, and it’s time to finish and set up the instrument. Setup and finishing are far too detailed to cover here. They could each exist as the own extremely detailed set of instructions.

There is an idea in my mind from the beginning. I have a mental image of the tone I seek. I work to make the structure stable and as under built as possible to allow the tone and resonance to shine. I have attempted to make this ladder bracing as resilient to the forces enacting upon the instrument as possible, and simultaneously flimsy enough to allow the top to vibrate and produce sound as intended. This top is incredibly lively and the tone of the instrument is wonderful. I have some more work to do to get the setup and playability where I want it. I do this work slowly; making minor changes as I play the instrument and taking the time necessary to think about what needs change. As you can see, this process was quite long and there is no way I could make a profitable living doing this. Even with the CNC use, this instrument is primarily hand made. Some will argue this point, so I have buried the statement down here at the end. If you're still here and reading then congratulations are due, you are among the small margin of brave folks willing to read this lengthy and somewhat absurd diatribe. Thanks for sticking to your guns and gutting it out with me. We should all do this aging sometime soon. I hope you enjoy this content as much as I have enjoyed producing it. Hopefully, I have illustrated the creative nature or at the least the kinds of creative possibilities aided by this new generation of tooling. We have a duty as to explore this terrain, not knowing what we will find around the next bend; happily continuing this intriguing journey. Now it’s your turn, I can’t wait to see what you folks can do with this.

Thanks!