Model C-17 Venetian Cutaway Claro Walnut and Curly Sinker Redwood
- Body Style: C-17 (Jumbo Venetian Cutaway)
- Upper Bout: 11.75″
- Waist: 10.5″
- Lower Bout: 17″
- Body Length: 20.5″
- Body Depth (Tail block): 5″
- Scale Length: 25.5″
- Soundboard: Curly Sinker Redwood
- Back and Sides: Claro Walnut
- Bracing: Laminated Adirondack Red Spruce and Carbon Fiber
- Bracing pattern: Back - Progressive, Soundboard - Conventional X
- Binding: Ceylon Ebony
- Soundhole Binding: Ceylon Ebony
- Rosette: Paua
- Neck: 5-piece Mahogany
- Fingerboard: Rosewood
- Fingerboard Inlay: Paua
- Headplate: Gabon Ebony
- Bridge: Rosewood
- End graft: Gabon Ebony
- Options: Arm Bevel
Fast-attack, fast-decay Curly Sinker Redwood is paired with fast-attack, fast-decay felled Claro Walnut and presented in a deep-bodied jumbo cutaway with an Everett-style transitional arm bevel for the fingerstyle guitar enthusiast. A judicious use of carbon fiber, coupled with progressive-style bracing combine with these superb woods to deliver a sweet sounding instrument with all the spaciousness, complexity and nuance you would expect from these materials.
The sides are thicknessed (thinned) to anywhere between 1.9 mm and 2.2 mm. This is an interactive, highly iterative process where I repeatedly pass the material through the drum sander and manually test the flex of the wood. I am looking for a particular range of response where I am able to bow the side without tremendous resistance. Each wood reacts differently and the thickness measurement can vary. The goal is to have the material thin enough to bend without it breaking, while being thick enough to support the instrument. This instrument will feature a Venetian cutaway, which incorporates a rather tight curve into the bend, so it is a good idea to remove a little extra material to avoid breakage.
You can get these sides pretty thin, especially if you support them with ribs. Be aware of the role that varying environmental factors play, especially on very thin wood.
Once the sides are at the proper thickness, I assess their layout. You kind of need to think upside down in a mirror to envision which side goes where. Getting this wrong can result in two left sides, or the grain pattern running precisely where you did *not* intend. The edge that will mate with the soundboard remains flat (my tops have a very shallow radius to them, anyway), so I mark the edge that will join the soundboard as my reference edge. The second reference that I will note is the location of the waist. This positions the bend relative to either end of the piece of wood. The edge that will mate with the back will have a contour (I use a fairly tight radius for my backs). I could bend the sides as perfect rectangles and manually shape the contour(s) later, but that is a rather tedious process and not without an element of risk.
It is possible to crack a side if too aggressive of an effort is made to shape it manually. Ask me how I know!
Rather than prototype every measurement, over and over again, I have a template I rely on to approximate the contour along the back edge of the sides, as well as to determine the overall width of the sides. It is important to note that pre-contouring the sides (removing what will eventually be excess material off the back) forces me to be extra considerate of the position of the waist of the guitar as I bend the sides. Indiscriminately bending without paying attention to this location could leave me with too narrow a side. With all that in mind, I trace the template, bandsaw off the excess material and verify that the soundboard edge and the waist are clearly marked.
I package a sandwich for my electric blanket side bender. I wrap the wood in aluminum foil so as to avoid any staining that may result from the interaction with the spring steel slats. I transfer the markings from the wood to the aluminum foil, and am now ready to bend.
300° persuades the wood to relax and another 15 to 20 minutes in the Side Bender “sets” the bend. I turn off the heat blanket and allow wood to cool down. After carefully removing it from both the Bending Jig and the aluminum foil, I get it into my shop-made body mold.
My Side Bender does not (yet) do a good job of bending the cutaway. Thankfully, Walnut is an easy wood to bend. I break out my trusty electric Side Bender and mount it to my bench. I use an iterative process consisting of spritzing the wood with water, applying heat and manual pressure, fitting the side to the body mold, visualizing any changes, and repeating the above as many times as needed to add the tight “cutaway” curves on one of the bent sides.
Make absolutely certain you select the correct side to add the cutaway bend to.
(Cutaway? Cutaway is something of a misnomer, as not having the body of the guitar exist in this area of the upper bout is very much a deliberate design implementation from the beginning. While still a major stretch, with a Florentine design one could almost imagine that the wood has been “cut away” from the body of the guitar, and the hollow recess filled in, allowing the hand to reach farther up the fingerboard. With the deliberately rounded curves of a Venetian-style design there is little evidence to suggest anything was ever “cut away”. I have proposed renaming this feature a BendAway, as in the wood has been bent, not cut, away from from where it would have been. Or perhaps it could be called an Out-Of-The-Way, as in out of the way of my hand? LOL)
To get this newly formed side into my shop-made body mold it is necessary to calculate and perform some trim cuts. You can view an article here where I detail the steps of my body mold construction. I have deliberately left both of the sides longer than their finished length in order to allow for any shifting mishaps during the bending process. I must remove that waste material now to properly seat these sides into the mold. I route and fit a tapered end graft onto the tail block ends of the sides. This permits me great freedom when trimming away excess material (the two sides do not need to butt up against one another perfectly). The neck block end of the cutaway side is left approximately 1 cm (3/8″) long, and is inserted into a pre-cut slot in my body mold. The other side is carefully trimmed to butt up against it, though binding will later be fitted perfectly where these two pieces join.
The tail block lets us join the two sides together at the lower bout end of the guitar, and provides much-needed support for adding a strap pin or a 1/4″ strap jack. On my guitars, this portion of the lower bout has a slight radius so it is necessary to shape the tail block accordingly.
I mark the tail block along each side for a visual reference.
I mark the center of the face of the tail block that will mate with the sides.
I take the wood to the sander to shape the radius.
Once the tail block is shaped to fit I trim (thin) it to size and rout a contour along the edge. I then glue it and clamp it in place, squaring it with the front edge of the sides (this is the “reference” edge of the sides, the edge that was left perfectly straight).
The process for adding the neck block is similar to adding the tail block. The neck block is squared where it will encounter the heel of the neck. It is slightly shaped to accommodate the curve of the Cutaway.
Both the back and the soundboard are “domed”, as in, they have a cupped curvature that is fixed by gluing pre-curved braces to an otherwise flat board. The sides must be shaped to accommodate this curvature. A preliminary neck block and tail block height adjustment, along with the side height adjustment is made possible by using the radius dish(es) with sandpaper attached. My radius dishes are approximately 24 inch diameter circles cut into MDF to achieve the desired concave curvature, measured as the radius of a large circle. I have one dish for each desired radius. A circular piece of coarse grit sandpaper is attached to provide a jig for accurately forming the curves of the front and back of the guitar body. The radius of the soundboard is much more shallow than the radius of the back; put another way, the soundboard is “flatter” than the back. Typically, less material needs to be removed from the front edge of the sides. The back will get a tighter radius so a little more effort needs to go into getting this shape sanded.
Remember that it is possible to crack a side if too aggressive of an effort is made to shape it manually. It is also possible to sand right past your target dimensions, so check those dimensions frequently.
This guitar is to be fitted with a transitional Arm Bevel. We are dealing with wood, not fabric, so we can’t simply “bend” or “wrap” the soundboard around to meet the side. Kent Everett developed a clever technique that I use here. A shaped wooden support is attached to the side, interrupting and replacing the kerfing where the arm lays across the lower bout, and forms a ledge on which the soundboard rests. The wooden support will eventually be overlaid with a veneer and blended into the binding, completing a smooth transition.
After deciding where to position the bevel, I mark the area on the side.
I carry the sides to my belt sander and carefully remove the marked area. I finish smoothing out the curve by hand.
My guitar body template has indicators where the Arm Bevel is position, so I am able to trace the shape onto a Basswood block.
A trip to the bandsaw will rough out the support and, using the belt sander, I can achieve a perfect fit inside the body.
Once the bevel support is glued in place, a little work from the inside of the box removes unnecessary material and smooths the transition into the kerfing.
Once the reverse kerfing is glued in place, the final side height adjustment is completed in the radius dish. If we have done everything correctly, we only need to “kiss” the radius dishes with the body of the guitar, as we are simply truing up the kerfing, at this point.
If, like me, you are shaping the sides manually, you will quickly realize the benefit of the earlier trip to the radius dish. There is less material to remove if the sides are sanded prior to installing the kerfing. The kerfing looks much nicer if it is of consistent height all around the perimeter, and this will *not* be the case if you add it first, then shape the sides.
Like the sides, the back is thicknessed (thinned) to an indeterminate measurement that typically ends up somewhere between 2.4 mm and 2.7 mm, depending upon the wood. Again, as with the sides, each piece of wood is different and the thickness measurement can vary. The goal is to remove all the unnecessary material that adds weight and dulls the overall tone of the finished instrument while maintaining sufficient structural integrity to hold it’s shape.
The back of the guitar will be glued in place, prior to attaching the soundboard. Since the joint between the kerfing and the back are visible through the soundhole, an opportunity presents itself to attach the back first, and spend some extra time cleaning up any glue squeeze out (without the soundboard in place the back is readily accessible).
However...I am incorporating an Arm Bevel and the soundboard will need to be modified where it lays across the arm Bevel support block. I could use an external template to determine the new shape of the soundboard, but this locks me in to either always creating an identical Arm Bevel, or having to prototype a new template for each and every Arm Bevel variation. It is much easier (and more precise) to use the body of the guitar to determine the exact location of the Arm Bevel. I set the body (still in the mold) face down onto the back side of the soundboard, position it correctly, and trace around the kerfing. Now I can return to preparing the back.
I prefer to rough cut the body shape out of the rectangular plate before adding bracing. If you have an existing template, you can simply position it on the (inside of the) back and trace both the perimeter shape and the brace positions.
If you do not have a template, you can center the body, still in the mold if your body mold allows, or carefully removed from the mold - so long as the shape does not distort. Place the body back side down, on the (inside of the) back. You may be tempted to trace around the inside perimeter of the back...In the pursuit of fine craftsmanship, don’t. Instead, trace around the the outside edge of the body. Remember that the inside of the back will be visible on the finished instrument, and pencil lines are unsightly.
In place of the ubiquitous ladder bracing, I prefer to use a progressive pattern, angling each brace away farther from the former, much like a fan. I cannot prove that this approach guarantees any improvement in sound or structural quality, but I know there is no detriment.
After carefully selecting the side of the back you want to be visible to the public, please remember to brace the other side of the back.
Here I have laid out the back bracing with blue tape:
I transfer the bracing layout onto my radius dish using chalk. I can then sand the correct contour into the brace by keeping the brace in it’s relative position on the radius dish (this sanding technique is not unique to my particular bracing pattern - it applies to any bracing pattern, including the commonly used parallel or “ladder” pattern).
The braces are pared down where they meet the sides. I use a low-tack tape that I can draw pencil lines on to help guide me through the manual process of shaping the ends of the braces. I accomplish the task using a curved paring chisel, a scraper, and sandpaper.
The outer rim of the back will lay on the ledge formed by the edge of the sides and the added kerfing (the edge of the sides by themselves would never support a strong glue joint). For structural (and, perhaps, sonic) purposes I rest the ends of all four (4) back braces onto notches cut into the sides, as opposed to stopping the braces short of the kerfing and solely attaching the Walnut of the back plate to the sides.
The back is glued on, clamped tightly in place and left to dry overnight. I add side bracing, next.
I subscribe to the theory that there is greater function to the side brace than merely assisting with the prevention of side cracks (for which a cloth patch would be sufficient). If I understand the transfer of string energy correctly, it is potentially moving to the back via both the bracing and the soundboard / side joint. Rather than employ a velocity dampening agent, such as a cloth material, I extend the reach of the brace material itself, being careful to fit everything tightly together.
This is a favorite pausing point of mine...where all this effort actually starts to look and feel like a guitar.
It’s time to prepare the soundboard with my Soundwaves inlay...
I use a template to mark the position of the braces and the soundhole. Once I know those positions, I can implement a rosette around the soundhole. For this instrument, I chose to inlay solid Rosewood rings, separated by a Paua shell ring, along with thin Paua soundwaves that appear to radiate out over where a pickguard would be (if I used one).
After the rosette has dried and I have scraped/sanded it smooth, I can flip the soundboard over and glue the soundboard reinforcement plate in place. Once that is done, I bind the soundhole.
Prior to attaching the back, I had positioned the soundboard and traced around the interior of the kerfing, being especially attentive to drawing a line where the Arm Bevel support contacts the soundboard.
The purpose of the pencil line now becomes evident: I need to remove the soundboard material in the area of the Arm Bevel, leaving just enough to rest on the ledge of the Arm Bevel support block. Once I have determined where the cut will be made, I am careful to reserve the waste material, as it can (optionally) be used in a later step.
After marking the bracing pattern on the radius dish with white chalk, I sand the proper curve into the respective brace(s).
Shining a light behind an un-sanded, flat brace demonstrates how the material needs to be removed from both ends. Once the brace seats nicely into the radius dish without having to apply pressure to bend it, it can be glued onto the soundboard.
The braces are glued onto the soundboard using Fish glue (Aliphatic Resin (White or Yellow AR) glue typically works fine for wood to wood bonds, but these braces include a carbon fiber lamination. I want the extra assurance of a good bond. I could use epoxy, but it is very messy to clean up. An animal protein glue provides just the right balance of adhesion and ease of application.
A thin (0.050″) carbon fiber plate is attached directly beneath the (pinless) bridge location using Fish glue.
The transverse brace is the only flat brace on this soundboard. Aptly named, it spans the area where the fingerboard extends out over the top the guitar. With a conventionally attached neck, be it glued-in dovetail or bolt-on mortise-and-tenon, I think of this area as the fulcrum, with both the body and the neck acting as levers once strings are attached and tensioned. A carbon fiber plate is attached directly behind the transverse brace, and acts as both a fingerboard patch as well as a support for attaching the fingerboard extension. The soundboard is complete.
Prior to attaching the soundboard to the body, I countersink some holes into the neck and tail blocks. The neck block will receive two bolts and washers to secure the neck. These bolts could easily sit atop the face of the neck block, but that would require a bit longer bolt, adding weight and being unsightly. The tail block will receive an endpin jack, and countersinking the inside face of the block ensures a proper fit. (I alternate between pre-drilling these holes and fighting to accurately position the blocks versus gluing the un-drilled blocks first and accurately positioning the holes - either approach works.)
Typically, the four ends of the X-Brace extend through the kerfing and the side. The soundboard is carefully positioned onto the body, the brace locations are marked, and small channels are routed through the rim (just as I did with the back braces). In this case, only three of those brace ends will pass all the way through the body, as I will terminate the end of the brace that encounters the arm bevel just shy of the exterior veneer. I simply notch a small ledge for the brace to rest on.
Glue is applied along the rim of the body and the soundboard is fitted into place. The soundboard goes face down into the radius dish to mitigate against unsightly runs and drips. Left to dry overnight, waste material is routed off the edge of the soundboard, and the body is ready for binding.
Binding contributes to the guitar in more than one way. Visually, it provides a pleasing (if not stunning) ornamentation to the instrument, in the way carpentry trim sets off casework, or pinstriping details an auto paint job. Sonically, it works to seal off the soundboard / body sides joint, forming something of a wall that can reflect soundwaves back across the top. Practically, it provides a buffer against unsightly and potentially damaging dents, nicks and dings.
Purfling adds an even greater degree of visual interest, and can be seen encircling soundholes, soundboards, backs and sides, necks and headstocks in all sorts of artistic ways.
Once a binding / purfling combination is decided upon, I like to build a small mock-up for measuring and test-fitting purposes.
I have a small jig that accommodates a piece of plywood clamped to it that acts as a template for setup and adjustment of my binding and purfling router attachment. A few iterations, and everything is dialed in accurately.
I set the guitar onto a cradle that holds the body somewhat level. A few careful passes around the rim of both the front and back of the guitar results in a stair step rabbet profile that will accept my binding / purfling combination. Due to the nature of my approach to creating the arm bevel, it is necessary to make a few very small adjustments with a small file to blend in the binding and purfling cuts.
Though only four (4) pieces of binding are needed in order to encircle the soundboard and the back, I like to bend a minimum of six (6) pieces, just in case. In this instance, I bent eight (8) pieces of binding. If all goes well, I will have four (4) pieces already bent for the next guitar.
For this guitar, in addition to outlining both the soundboard and the back with purfling, I am using purfling on the sides. This requires the purfling be bent in a manner in which it would rather not bend. I assist it’s compliance using a heat gun and hold it in place on my side bender until it is needed.
I bend the binding in the location of the cutaway by hand using four (4) tools: an electric hand bender (an iron pipe and propane torch work just as well and heat up and cool down much faster, but I am uncomfortable with the presence of the open flame in my location), a wooden bending template (for test-fitting), leather welding gloves (to withstand the inevitable contact with 375°), and a small pot of boiling water (in some cases, I prefer to use a heat gun instead of the hot water. Alternatively, depending upon the wood I am using, I might use a spray / spritz bottle of water). Dipping the end of the pre-bent binding into the hot water for a few seconds, then gently working it on the electric hand bender, test-fitting it on my wooden bending template, and repeating the process until the binding follows the template without having to force it has proven to be a consistently successful technique for me.
A note regarding using a (wooden) body template for hand-bending: You may experience less frustration if you take the time to size this template to the inner dimensions of your guitar body, as opposed to the outer dimensions. In other words, don’t simply trace the outline of your guitar body or soundboard template as a guide for bending. Your sides and/or binding will come out slightly too large.
The cutaway side gets bound like any other guitar side having a cutaway, but the presence of an arm bevel on the non-cutaway side of the soundboard requires a slight change in approach. The binding must follow the contour that I cut into the side in an earlier step. At the same time, the purfling must follow the curve that was cut into the soundboard. Effectively, at both ends of the arm bevel, the binding and purfling separate to outline the arm bevel.
In order to reduce the amount of dexterity required to manipulate and glue the bindings and purflings into place, all at the same time, I attach the side purfling first. I hold it in place with tape and affix it with CA glue. Push pins help the purfling follow the contours of the arm bevel until the glue forms a permanent bond.
To shape the binding to follow the contour cut into the side, I mark the binding at the points where it will be flush with the soundboard and carefully belt sand a contour into it between those marks. This relieves a great deal of stress as the binding is bent to follow the curvature, stress that would otherwise certainly crack the binding. As you will see, the bevel will blend nicely into the binding, and this preliminary removal of material will not be detrimental to the finished appearance.
You may recall that we saved the soundboard cutoff from when we removed the material to rest on the arm bevel ledge. Here, along with a couple of thin strips of dark wood, that cutoff is re-attached. Due to the sharp angle of this particular arm bevel, the extra material allows for an improved transition from the soundboard to the side.
Using the soundboard cutoff.
EDIT: I would not recommend attaching the purfling to the soundboard as a separate step from adding the soundboard cutoff, as there is a high probability the push pins will introduce a permanent wave into the purfling, one that cannot be adjusted by filing. Instead, set the purfling in place, press the soundboard cutoff against it, and then pin everything down while the glue dries.
Using a wood rasp, a scraper and sandpaper the bevel is shaped. It is very important to remove only the necessary material and nothing else. On the soundboard that means shaping right up to, but not into, the purfling. There can be a little more flexibility on the sides, depending on how much binding is available to remove. The preliminary shaping looks like this:
When doing work such as this by hand, it is critical to pay attention to the direction of the file or rasp. It is easy to catch and tear material. If you envision a centerline running parallel between the purflings and work from the purflings toward the centerline you will be less apt to make a regrettable mistake.
I choose not to build these arm bevels identical in size and shape, allowing me the opportunity to customize each guitar to each player’s preference. As every guitar is different, a standardized veneer template will not suffice. I am able to quickly create a template of the shape of the particular arm bevel by smoothing a piece of aluminum foil across it.
I (temporarily) affix the foil to my veneer stock and cut out a slightly oversized piece using scissors.
It is entirely possible to simply grab the glue and stick the veneer to the bevel. However, the compound curve creates a bit of a clamping challenge and gaps can occur. An easier (read: foolproof) method for applying the veneer is to first coat both the arm bevel and the backside of the veneer with a thin film of glue. After it dries, a light pass with sandpaper over both glued surfaces will remove any raised grain, dust, irregularities, etc. Using a hot iron (a laundry iron will work, I just happen to have a lightweight craft iron / heat sealing tool) instantly bonds the two glued surface together. Carefully positioning the veneer prior to touching it with the hot iron is advisable.
Carefully slide a razor blade along the veneer, just shy of the finished dimensions, making certain not to cut past the bond between the veneer and the arm bevel. Finish with sandpaper (sanding block, power sander, etc.).