1999 Guild JF65-12 Overhaul
Guild's top-of-the-line Maple 12 string in 1999 was called the JF65-12 (prior to this name change it was known as the F-412). This particular guitar had suffered a soundboard split along the fingerboard extension and into the soundhole, an all-too-common occurrence in these instruments. It is impressive that these cracks occur despite the amount of braces and patches glued to the underside of the top. In addition to needing a neck reset, the guitar was generally lackluster, both visually and aurally. The owner had sensed the soft cry of potential from his favored Guild, and set out to pursue his upgrade options. Rather than trade out guitars, and inherit an all new set of issues, he wisely chose the overhaul path. We conversed at length, discussing his goals and desires and determined to replace and improve the top, add tasteful inlay, and refinish the guitar with a smoked glass appearance, a technique that can really pronounce the best visual aspects of the underlying Maple (and something the owner had hoped to do for a long time). The guitar was packaged up carefully and shipped to me via FedEx Ground, arriving without damage.
In addition to the crack in the soundboard, the wood selection for the top was less than stellar. I would rate it a 2A Sitka top, at best. It had an interesting chatoyance in the lower bout, along with a rather pronounced distinction in ever-widening grain width. The neck had the slightest twist in it (something that I was able to readily verify once I removed it). The body had a slight twist in it on the treble side upper bout, preventing it from resting firmly on its sides. Otherwise, the guitar was in relatively fine shape, exhibiting very few visual imperfections (dings, scratches, etc). The binding was loose around the fretboard, but I would either be re-glueing it or replacing it, so I did not consider it to be a problem. Overall, this was a well cared for instrument. I recorded a brief sample of the sound of the guitar for comparison, later. (This was recorded using the old strings, just prior to deconstructing the guitar.)
1999 Guild JF65-12 - Before
Off with the strings! It was time to get down to business. My first task was to “unbuild” the guitar, taking it down to its base components. This involved removing all the hardware, removing the nut and saddle, removing the pickguard, removing the bridge, removing the frets, and then removing the soundboard...
Ready for Surgery
I would be refinishing this guitar, but that is never an excuse to take shortcuts. When removing the nut, it is customary to first carefully scribe around the ends with a scalpel in the event any finish was sprayed over the nut. Using a small tool and a hammer, a sharp RAP to one end or the other should be enough to break the nut free (assuming the last person to touch applied a dot of glue to the fretboard edge of the nut). In this case, the nut let go without drama.
If you look closely at the plastic fretboard binding near the 1st string (on your left, in the photo) you can see the shrinkage that has occurred, where the binding stops well short of the end of the fretboard.
This was a well-fitted bone nut, properly seated and properly glued. It came out cleanly.
All the hardware was removed. This included the tuning machine heads and the truss rod cover. These parts went into a bag for safe keeping, along with the nut, saddle and end pin. With the bag labeled and neatly tucked away in the accessory compartment of the guitar case, the hardware parts await re-installation.
Partly due to the fact that I knew I would be replacing the soundboard and partly inspired by my desire to try out a new hair dryer, I tackled the removal of the pickguard. This guitar was built late enough to be fitted with an adhesive backed pickguard, rather than the lacquered-on celluloid of old. The plastic pickguard lifted right off the adhesive using the hair dryer in conjunction with a spatula/palette knife. The adhesive, however, took another 20 minutes to remove using Naptha and some serious elbow grease.
This guitar had been finished using a clear nitrocellulose lacquer (NCL). Over the years the clear finish had yellowed, as can be seen when contrasted with the finish beneath the pickguard. What is often thought to be the patina (a natural discoloration of the wood as it ages) may only be a visual illusion. In this case, it is the lacquer that has yellowed, not the wood.
Guild pickguards, while maintaining the same basic shape, came in a variety of sizes, having slightly different contours over the years. Nevertheless they were all readily identifiable, and this one is quintessential Guild!
1999 Guild JF65-12 Pickguard
It was time to take off the bridge. This bridge had been re-glued so potential surprises awaited me. But alas, there was no drama. The bridge came right off with a little heat and coaxing.
Guild bridges can also vary a bit in appearance, size and shape from guitar to guitar, but maintain the overall look of the brand. I am torn whether to remake this bridge, or try to use the old one. We'll see...
1999 Guild JF65-12 Bridge
Now that the fun stuff was behind me, I tackled the frets. Years ago I would touch each fretwire with a soldering iron prior to applying my nippers to the fret in order to soften any glue used and minimize chipping of the wood. These days it is all hair dryer, especially around plastic binding (which a soldering iron can easily burn and/or melt). These frets came out with zero chip-out!
Next I set out to remove the neck. In my experience, Guild dovetail mortises generally measure 1-5/16 inches at the top, outermost edge and widen to approximately 1-7/16 inches at the top back, which can be anywhere from 1/2 inch to 5/8 inch deep. Two holes are drilled in the fret slot nearest the body joint, following the dovetail angle, a rather shallow 10°.
Drill Fretboard for Neck Removal
At this point I hit my first obstacle: the neck did not want to release. Having sailed these waters before (and suspecting a heavy application of glue), rather than risk any damage I opted to simply remove the fretboard to see what I was up against.
NOTE: Were I not rebuilding this instrument this would have been a different story. For those who do not have the option to go where I went, I sympathize. These are the cases where extra effort must be applied, and extra care must be taken to avoid mishaps.
Prior to taking off the fretboard, I needed to address the fretboard binding. With the frets removed the fretboard binding was practically falling off, almost as though it had never been glued on. It had shrunk away from the nut on both sides and that began its multi-year demise as it broke free from its glue bond.
Fretboard Binding Falling Off
When I said I was going to “unbuild” this Guild, I had not intended to go quite this far.
Fretboard Binding Completely Removed
Now, with the binding out of the way, I softened the glue beneath the fretboard and lifted it off.
The fretboard was then clamped dead flat, to rest overnight.
1999 Guild JF65-12 Fretboard
The ideal dovetail joint has minimal space between the face of the mortise (on the neck block) and the face of the tenon (on the neck), and fits tightly along the sides, requiring very little glue to hold it in place. Less space translates to less cavernous gap that (should not, but) can be flooded with glue.
Complicating matters, this is an older Guild 12 string that features two (2) compression rods in place of today's more common lone dual-action truss rod. These rods were installed installed into twin slots running the length of the neck and secured at one end by drilling two (2) 1/2″ holes into the end of the tenon to receive the flat, fixed end of each rod. This results in removing a rather large amount of tenon wood, making way for an even larger potential glue reservoir.
This was one of those occasional Guild guitars that you hear about, the one with more glue in the dovetail joint than would likely be necessary to completely build two more guitars!
Glue in the Neck Joint
When you get the measurements right, and the angles right, the holes drilled through the fretboard go right down into the dovetail/mortise joint. Perfect aim!
Holes in the Neck Joint
I drilled a hole in the cavity between the tenon on the neck and the mortise of the neck block. I already had two angled holes drilled, one along each side of the dovetail. Now, with three holes in total, this neck stood no chance of continued resistance. Using a few droplets of water, injected into each hole, along with my Stew-Mac HeatStick, and alternating between the three holes, I was able to take the neck off and avoid any water or steam damage, let alone any unsightly dripping or pouring glue all over the inside of the guitar.
With the neck removed from the instrument and the fretboard removed, I first cleaned the glue out of the mortise in the body and off of the tenon of the neck. This neck is very sloppy in the joint, and required a copious amount of glue to hold it in place. This factor alone easily accounts for the difficulty I encountered when trying to remove the neck. In may case, the extra glue I cleaned out of the two (2) 1/2″ holes in the tenon compounded the difficulty. This dovetail joint will be fully addressed later, when it comes time to fit the neck back to the body. At this stage I loosened the twin compression rod nuts and clamped the neck flat on a bench.
Neck Clamped Flat
Next up was the removal of the soundboard. I had a router bit made years ago by the awesome folks at Whiteside, here in the Carolinas. It is an extremely thin carbide wheel cutter with an offset bearing that lets me run a router around the edge of the soundboard and it cuts through the binding and kerfing. A small saw can be used to free the top from the heel/end and neck blocks, and/or where the braces are inset. In the interest of time I will often rout through the soundboard, around the blocks, just to get the top off. But I wanted to save this top, especially the area above the neck block, as it is a really good example of the notorious soundhole split. In order to effect this removal I used heat and my palette knife and the soundboard was removed.
This particular Guild was constructed with solid Maple sides and a laminated arched back with a three-piece Maple-Mahaogany-Maple neck. This image as seen from the tail block reveals the wood used for the sides.
Solid Maple Sides
Here are the components of this deconstructed Guild.
1999 Guild JF65-12 Deconstructed
1999 Guild JF65-12 Deconstructed - Bracing
A little more deconstruction was necessary before I could start re-building this 12 string. Removing the top may also remove some of the kerfing, leaving it shorter than desired. Additionally, X-braces are typically let into the kerfing in order to rest the ends of the X on the sides. On the Guild, two (2) of the three (3) finger braces (per side) are also let into the kerfing, instead of terminating them just shy of reaching the sides. All this extra routing leaves large gouges for the soundboard to span, resulting in very little positive contact with the sides. That perfect contact all around the edge of the soundboard is critical for generating the standing waves responsible for the sound we hear from the guitar.
I removed the old kerfing around the soundboard edge of the sides.
I opted to replace the old kerfing with a higher quality reverse kerfing. I first wet the wooden kerfing strip and then clamp it, backwards, to the outside rim of the body. In this way it takes the shape of body and I can apply it to the inside as a unified whole, without breaking it in multiple places and having to splice it constantly.
Forming the Kerfing
Acoustic guitar soundboards are not technically glued to the sides of the body, at least not directly, as there is insufficient surface area to hold the pieces meeting at 90° together under any kind of stress (the same is true for the backs of the guitars). Kerfing supplies the surface for the front and back plates to attach to. Kerfing is first glued to the sides, and then the plates, front or back, are glued to the kerfing.
It is called kerfing, or kerfed lining, due to the numerous slots, or saw kerfs, cut deep into a strip of wood in order to more easily accommodate bending around the curves of a guitar body. The early Spanish guitars used tiny, individual rectangular pieces of wood, called tentallones, that were applied one-by-one. The introduction of kerfing improved both the efficiency of application and added a degree of stiffness to the joint, thus improving overall tone. The early versions of kerfing were simply triangular strips of wood that had slots cut into them. Variations of this style are used to this day.
Reverse kerfing is a measurably stiffer component than its predecessor, and is even more efficient to apply. Essentially, it is much akin to the original form of kerfing turned inside out. It creates a more rigid shelf, or ledge, at the point where the soundboard makes first contact with it. Here it is, glued in place.
At this stage of any build it is customary to radius this face of the body in preparation to receive the soundboard. Rather than alter the depth of the sides I set the kerfing a little high, allowing for the kerfing to be sanded to the correct radius, not the sides. A short time at the radius dish and the desired profile was obtained.
Radiusing the Kerfing
With the new kerfing in place, it was time to add bracing to the sides. Side reinforcement was approached differently over the decades. In an effort to control side splits, some builders applied tape across the side wood. Here is a 1975 Guild F-212 with copious amounts of tape in place.
1975 Guild F-212 Side Tape
By the time I returned to building guitars, in lieu of tape, many builders were installing actual braces across the grain of the sides. In the case of X-braced guitars, I have had good success in tying the placement of side braces to the ends of the X. Additional braces are added at points of stress.
With the new kerfing in place and radiused to receive the new soundboard, and the side braces added to stiffen the sides and mitigate stress fractures, the only thing left is to address the off-center placement of the label (thanks to the eagle eye of the owner).
Inside the Box
The soundboard is the primary driver of the sound we associate with the acoustic guitar. And the area of greatest interest on any given guitar soundboard, the so-called beachfront property, is located between the bridge and the tail block. All other things being equal, I want a board that is aurally lively in that area. I selected a AAAA Sitka Spruce top that is approximately 20 years old for the job. I have added a rosette, combining two classic Guild white and black ABS trim rings with a Paua ring in between. The Paua will also outline the entire soundboard. Here is a preview, taken prior to applying the bracing...
In addition to preventing the pull of the steel strings from collapsing the body of the instrument, soundboard bracing controls, or shapes, the sound. In addition to a traditional straight, X-brace that spans the upper and lower bouts of the front plate and intersects just behind the soundhole, Guild Jumbo 12 strings traditionally use six (6) finger braces (three (3) per side) and three (3) tone bars to round out the bracing. While four (4) finger braces (two (2) per side) and a total of two (2) Tonebars are sufficient, I want to stay in the audio spectrum of the quintessential Guild sound so I will add the extra braces.
The old lacquer needed to be removed in preparation for a brand new finish. There are four (4) techniques available to the finish remover: solvents, heat, sanding and scraping. Harsh chemical solvents can soften glue joints and, in the case of this guitar, will definitely melt off the plastic binding. Heat is the enemy of glue joints and, unless you are deliberately attempting to further disassemble the guitar, should be avoided. The arched back of this 12 string is a laminate comprised of two layers of maple and glue that was pressed into shape with heat. It does not need to be reheated at this point in its life. Sanding is not a great idea for finish removal when our material is already at dimension; the sides and back are as thin as they need to be. Sanding risks thinning them further, and that must also be avoided. The best way to safely remove this old finish is to scrape it off.
Scraping off the old finish
Scraping off a lacquer finish is a time-consuming process. It is important to keep the scraper razor sharp, so as to maximize each pass.
Scraping the back
Eventually a visual distinction makes evident what scraping work remains.
Scraping nearly complete
Thousands of passes later, the body is scraped clean.
To improve the overall stiffness of the neck I added a carbon fiber rod. The Guild 12 strings of this era featured a twin compression rod system designed to counteract the forward bow of the strings. The carbon fiber rod was epoxied down the exact center of the neck, in between the two compression rods. The neck was clamped dead flat while the epoxy set. The result was a perfectly straight neck with no twist!
Carbon Fiber Rod
Center soundhole soundboards share a common bracing pattern, that being the X-brace developed and perfected by the Martin company. The cross of the X sits just below the soundhole, reinforcing / adding strength back to the giant 4 inch hole that was cut in the soundboard. The arms of the X reach up around the hole and rest on the rim formed where the sides meet the kerfing in the area called the upper bout. The lower legs of the X also rest on the rim of the sides and extend into the area referred to as the lower bout.
I have learned through experimentation that by slightly widening the X on the lower legs I can get an increased bass response from these Guilds. Never boomy, just better.
X Brace Widened
Bracing material, shape and dimensions vary among designers and builders, as the measurements determine the stiffness and/or strength of these crucial support beams, and everybody has their own idea regarding what combination of material, shape and dimensions make for the best solution. The primary role of the X brace is to counteract the pull of the strings that, with no bracing in place, would simply collapse the soundboard into the box.
A radius is sanded into each brace that results in a slight domed effect across the face of the soundboard. The tighter the radius, the more pronounced the dome, or arched, effect, and the stronger the soundboard (think: suspension bridges). Strength comes at a price, however, and that price is reduced volume. Flatter equals louder. The generation of acoustic guitars that this 12 string came from back in the late 60s and early 70s were called “flattops” due to the flatter (less arched) soundboards. I am using a relatively flat 52 foot radius for this 12 string. I will leave the braces taller to support the flatter top than if I were tightening that radius to a more commonly used 28 foot radius. The original braces measured 3/8 of an inch thick by 3/4 of an inch high, where I am reducing the width of these to 5/16 inch and increasing the height to 7/8 of an inch. Thinner and taller for superior sustain.
The braces must be strong enough to counter the effort to collapse the top, but not so as to add damping and unnecessary weight to the soundboard. Additionally, there is a balance to be achieved between strength and stiffness, where the top is properly supported and the entire top is stiff enough to promote the free travel of kinetic energy across the surface. If the soundboard is too stiff, the top will never get set into motion, and there is little sound generated.
The soundboard braces I have fashioned for this Guild come from very stiff, straight grained Adirondack (Red) Spruce.
X Brace in the Go Bar Deck
While this topic should be (and may yet become) an article unto itself, it is a good time to address it as my center soundhole soundboard construction technique is born from overcoming the need to reset the necks on these instruments. There are only a few components involved that can possibly contribute to the condition where the neck of an acoustic guitar must be removed, its angle of incidence (where it contacts the body) altered and be re-attached. Necks can bow forward beyond the point at which they are correctable short of surgery. Bellies can pull upwards (due to insufficient bracing and/or brace failure) where the only option is to remove the neck. But the number one contributor to the need for a neck reset is something called a neck block shift. A change in the relationship between the neck block, the sides, the back, the kerfing and the soundboard allows the entire neck system to plunge forward, in towards the soundhole. Often, the stress preventing such a change is overcome in a soundboard shear along the fingerboard extension.
Viewed from inside, the damage is almost imperceptible, but the split is clean through the soundboard. It is enough to allow the soundboard and company to shift forward (toward the bridge), contributing to the raised action and need for a neck reset.
Soundboard Shear - Inside
The upper bout of a center soundhole soundboard serves a negligible role in the generation of any significant sound. Rather than tip-toe around this fact I learned to embrace it. I was able to see the solution perfectly framed within the X Brace design.
Space Framed by the X Brace
Two pieces of Mahogany are epoxy laminated directly onto the soundboard in the upper bout spaced framed by the X Brace. I cut the soundhole out of each piece, slightly larger than the soundhole in the soundboard...
I am careful to orient the Mahogany pieces such that none of the grain direction of any of the three (3) plates (soundboard and 2 Mahogany plates) are running parallel.
Just in case anyone was wondering: the extra pieces of wood in the photo, above, are being used a cauls to distribute the clamping pressure from the fiberglass rods. They are not part of the finished solution.
Once the soundboard is fitted into the body and epoxied in place, this approach forms an impressively strong, light-weight cohesive union of soundboard, X Brace, Neck Block, Sides and Back. I have not had a guitar retrofitted this way experience a neck block shift, as there is nothing to shift.
The X Brace gets shaped to reduce unnecessary weight.
Shaping the X Brace
All braces must fit the contour of the domed soundboard. The so-called Finger Braces first get sanded in place on the radius dish (in the same place they will be glued to the soundboard). Then they get glued into place.
The bridgeplate resides directly beneath the bridge and sandwiches the soundboard between itself and the bridge. Its primary role is to mitigate the tearout that would occur as the ball ends of the strings that pass down through the bridge pin holes pull against (and through) a softwood such as Spruce. A good choice for a bridgeplate is a hard, oily wood such as Rosewood. Debates rage as to the significance of the secondary value of the bridgeplate in its lesser role as a contributor to sound. The consensus leans toward Maple being the wood of choice for a bright, non-damping brace. For my bridgeplates, I split the difference between the benefits of the two (2) woods and laminate a plate of Rosewood with a plate of Maple. I get the best of both worlds.
The so-called Tonebars run diagonally across the lower bout and serve both to distribute the kinetic energy of the strings across the surface of the soundboard as well as to provide structural support in the belly area below the bridge. In Guild's case, they used three (3) Tonebars. While two (2) are sufficient (yes, even for a 12 string), the sound will change and no longer be identifiably Guild. That is not the goal.
- Guilds are not known to have responsive soundboards
- I do not want to so dramatically alter the soundboard as to lose the Guild sound
- The goal is to improve the soundboard responsiveness while keeping the Guild sound
Using an iterative process of lightly holding the soundboard and rapping it in the lower bout to listen to the response I scalloped the Tonebars and the X Brace for a brighter overall sound. Leaving the bracing all at the same height, while potentially enhancing the low end (which I achieve by slightly widening the legs of the X Brace), typically results in a soundboard that is a bit too tight. It also adds unnecessary weight.
The original soundboard weighed a svelte 13.7 oz. The new soundboard weighs 14.8 oz (the weight of this new board will be further reduced once it is attached to the body, as it has yet to be sanded to final dimensions, and twelve (12) holes will be drilled through the top and out of the heavy rosewood/maple bridgeplate). It is safe to say there is less than 1 ounce difference between the boards, with my version having no need for additional upper bout bracing (transverse brace, fingerboard patch, etc.). The primary purpose of this approach is to tie the sides, back and neck block together as a unified whole, eliminating the future need for a neck reset.
And did I mention that the new soundboard will sound better, richer, having greater sustain? Better materials, better craftsmanship, greater responsiveness.
Fitting the Soundboard
As mentioned during the assessment, the body of this 12 string has a slight twist in it, a very common issue. My own Guild 12 strings each have such a feature. This can be readily seen when attempting to rest an acoustic guitar on its sides. Ideally, when turned on either side, the body of an acoustic guitar will sit solidly on a flat plane, where both the lower bout (hips) and the upper bout (shoulders) rest firmly on that surface. Like many, this guitar had a different understanding of that notion. When the lower bout on the treble (1st string) side was pressed firmly against the flat surface, the upper bout would only touch at the back of the side. The soundboard side was twisted up and away from the surface approximately 1/4" of an inch. This was a good indication that the instrument was probably not well-secured in a body mold (a jig/fixture designed to hold the sides of the body in a specific shape) throughout its entire construction.
Upper Bout Twist
Throughout construction the body should be held in that same position that was achieved after attaching the sides to the tail block, neck block and kerfing while both the back and the soundboard are attached. Under no circumstances should the completed sides, tail block, neck block and kerfing be stressed, torqued and/or twisted after glue-up into a new shape while the back and/or soundboard are attached. It is ill-advised to ever attempt to force the sides into a new shape and believe that they can be held there by gluing the soundboard on.
Correcting such a twist in this body would require a complete disassembly of the guitar: removing the back, removing the neck block, re-aligning the sides... essentially starting over. This issue in the upper bout, where the wall of the side leans in slightly toward the soundhole, has zero affect on the sound. Since the waist of the guitar (where it rests on the leg of the player) is properly perpendicular (not twisted) and play comfort is not compromised, we are in fine shape going forward.
With the body secured in a body mold, the the first step in fitting the soundboard is to identify the centerline. On many pre-robotics factory-built instruments this can be a daunting task. This guitar is a good example, where neither the neck block or the tail block were accurately centered on the sides. However, a visual centerline has been determined by the plastic V-trim at the tail block and by the meeting of the back binding at the neck block. Short of a complete disassembly, this is what I must use for the positioning of the soundboard - not the centerlines of the neck and tail blocks.
Piecing this all together, I surmise that the old soundboard had been glued onto a rather imperfect side assembly which had been forced back into a body bold under tension to try to straighten it out. Eventually, the weakest link failed and the soundboard sheared in toward the soundhole.
When the guitar was first built, as a result of the neck block not being centered, the dovetail mortise was cut off center in order to align the neck with the body.
Neck Block Centerline
Regardless of how off-center the tail block may be when compared with the visual centerline determined by the plastic V-trim, that visual centerline is what the soundboard centerline will now be aligned with.
Tail Block Centerline
To fit a traditional X Braced soundboard, the ends the X Brace along with the ends of the Transverse Brace are let into the kerfing and sides (as mentioned earlier, Guilds will also let in two (2) of the three (3) Finger Braces on each side). For this soundboard, I will let in the ends of the lower legs of the X Brace along with the entire upper bout.
Kerfing Notched for X Brace
A sharp chisel, a small handplane, and 1 hour were all that were required to ensure a perfect fit. I reduced the height of the neck block, kerfing and sides in the upper bout area by the height of the two (2) Mahogany plates. Of course it would be easier to have cut those plates to fit inside the kerfing, but then we are largely back to where we started, where the only thing holding everything together is the thin Spruce soundboard glued to the kerfing. The body is now ready to receive the new soundboard.
Ready for the Soundboard
Glue is applied to the kerfing, Tail and Neck block surfaces and the soundboard is clamped into place.
Prepping for Binding
The binding router follows the sides as a reference in order to determine how far into the top the purfling channel extends. Trimming the soundboard flush with the sides is necessary to ensure the binding router has a perfectly smooth reference to follow.
Soundboard Trimmed Flush with the Sides
Here is a close-up of the glue-up, highlighting the depth of the soundboard throughout the upper bout. When the binding is applied, only the Maple side will be visible; the Mahogany and Spruce layers will be underneath the binding.