A deep dive into the topic of Guild neck resets, using my own 1976 F-212 XL as an example. Dedicated to Guild owners everywhere ...
My 1976 Guild F-212 XL is in need of a neck reset. Guild guitars are party to a legendary reputation for being difficult to disassemble. While there is some justification for the stigma, particularly among some of the older guitars, the entire brand certainly doesn't deserve being accused.
Giving this guitar the benefit of the doubt, let's see how easy or difficult the neck is to remove. This article is dedicated to the countless Guild acoustic guitar owners whose guitars have desperately needed a neck reset.
For details regarding neck resets, what they are, how to determine if and when they are needed, etc., I encourage you to read my article » Neck Resets.
Rather than re-visit the contents of that rather lengthy article again, here, I am going to highlight what is going on with this 50-year-old Guild 12-string that informs me of the need for a neck reset.
This 12-string guitar has become increasingly difficult to play, over time, as the action has raised. It is currently twice as high as it should be!
I want to stay with light-gauge strings and get the action as low as possible without constant string-to-fret contact ("buzz") for my style of playing. To go any lower, I could increase the string gauge (to mitigate buzz), but the increased tension of heavier gauge strings makes the guitar feel "harder" to play.
Perhaps more concerning, heavier gauge strings could exacerbate the condition that caused the need for a neck reset in the first place. But I am getting way ahead of my story.
How do I know for certain that this guitar requires a neck reset? To answer that, I need to make a few assessments.
Damage. Is there any damage that would preclude my resetting of the neck? The most pertinent damage, that which would stop me in my tracks, would be soundboard shear. Like this:
But it doesn't need to be that obvious to still qualify as damage. Like this:
In the case of my 12-string, the strings are pulling the neck block in the direction of the bridge to the tune of 250 lbs. The only thing keeping it from going there is a 5" long strip of Spruce 0.100" thick. If that Spruce has already split along its grain, I have a real problem.
Let me show you how to compound that problem. I introduce sufficient heat, moisture and racking back and forth of the neck during removal to steam open the dovetail, while that same heat, moisture and racking also relocates the neck block in relation to its original installed position.
I just super-softened all of the adhesive at the intersection of the back, sides, soundboard, and neck, the veritable Town Square of the acoustic guitar. That's just great, especially considering that I made all of my neck angle calculations prior to potentially changing everything during the removal!
But I can make this worse by missing or ignoring a split in the soundboard. I can complete my glorious neck reset, oblivious to the fact that as soon as I string up the guitar, I return the 250 lbs of tension to the neck block which has nothing holding it securely away from shifting toward the bridge.
What do I get for all my trouble? At the very least, tuning instability issues and a taller action than I was expecting, seeing as how I just reset the neck. Sadly, this scenario is more common than you might have guessed.
I have an article dedicated to this issue, if you want to read more about it. It's here » Body Flexion - Neck Block Shift and Soundboard Shear.
This guitar has not suffered any shearing of the soundboard, so I am going to proceed with my assessments to determine if a neck reset is really necessary.
Five of my seven assessments used to determine whether a neck reset is warranted, or not, passed. The two assessments that failed are such exceptional examples of failure that I am going to include them here, for posterity.
Failure #1 - Overall String Height: The height of the strings from the soundboard, as measured directly in front of the bridge, is both relative to the class of guitar being measured, and an indicator of performance potential.
This 12-string belongs to a class of steel string acoustic guitars that generally benefit from an overall string height of +/- 1/2". The metrics surrounding the soundboard stiffness dictate the height needed to generate sufficient torque to drive the top. These guitars were heavily braced. A shorter bridge results in diminished output.
Target height roughly translates to a 3/8" tall bridge and a saddle that projects another 1/8" above the bridge. I have established that the saddle on this guitar is, indeed, projecting 1/8" above the bridge.
However, the current bridge is less than 1/4" tall. The overall string height on this guitar comes in below 3/8".
When pursuing the need for a neck reset, it is common to lay a straightedge across the fretboard and note where the plane of the frets sits in relation to the top of the bridge.
Look at that! This "straightedge test" seemingly passes! Coupled with the fact that, standing almost 1/8" above the bridge, it appears that there is "plenty of saddle" remaining, standard thinking suggests I can just whack material off the saddle to lower the action.
It is a good thing I know about my Overall String Height discrepancy, otherwise I could make a serious mistake. But wait, there's more. I have another failed assessment, and that warrants discussion.
Failure #2 - Action Height: This guitar's action is extremely high. As an isolated issue, big deal. We manage high action all the time. What makes this guitar so interesting is that all the other assessments check out. Even the "straightedge test" with "plenty of saddle" remaining says everything is fine. I am going to show you why it isn't fine!
Fitted with light-gauge strings, and tuned to "Concert" (Standard, A=440 Hz) pitch, the 11th string is 5/32" (4.0 mm) away from the 12th fret.
My target height for that string is 1/2 its current height, at just barely over 5/64", or 2.0 mm.
An improper, though extremely common approach to achieving a target action height is to adjust the saddle height. In this case, I would need to lower the saddle by sanding material off of its bottom, in order to preserve any radius and compensation filed into its top.
How much material would I need to remove? Here is how to calculate that:
On the fretboard, the 12th fret sits at a point approximately 1/2 way between the nut and the saddle. I measure Action at the 12th fret. I can therefore understand the relationship between the string height at the 12th fret and the saddle height at the bridge by using a multiplier of 2. For each unit of measure ("n") that I consider modifying at the 12th fret, I double that unit of measure ("n x 2") to determine how much material to remove from the base of the saddle.
Example: I want to lower my action on the bass string at the 12th fret from its current height of 5/32" (10/64") down to 5/64". Perhaps less confusingly, I want to go from a 4.0mm Action down to 2.0mm. My saddle currently projects ≈ 1/8" (3.0 mm) above the bridge.
I have a big problem! If I sand off that much material, my saddle will disappear below the top of the bridge.
I only have 3.1 mm (a little less than 1/8", or 8/64") of saddle projecting above the bridge, and that is measuring at its highest point. To lower my Action, the calculation tells me to reduce the saddle height by 4.0 mm (or 10/64"). That will literally "bury" the saddle down into the slot!
This is why it is important to run all seven (7) assessments, not just the "straightedge test" along with the "plenty of saddle remaining" evaluation.
Per Failure #1, I will be replacing the bridge with one that is sufficiently tall enough to satisfy my Overall String Height requirements. I will remove the frets and plane the fretboard dead flat. I will be resetting the neck to correct the geometry, targeting my new bridge height, such that my straightedge test is successful. But about that geometry stuff ...
Before I remove anything, I want to measure top deflection. I need to know how much allowance to make for the nominal bellying (which I have visually identified).
It is so important to validate top deflection with measurements, as opposed to just assuming. A condition exists where a a bridge will rotate forward under string tension and pull the belly upward behind it. But, at the same time, it will create a depression in front of the bridge, driving the top downward. The net result may be zero overall height change, even though it "looks" like the top is bellying.
I will take two measurements at the top of the bridge, relative to the soundboard edge of the sides at the lower bout, using a dial indicator fitted to a gantry. The first measurement will be taken with the strings tuned to pitch.
The second measurement, taken in precisely the same position, will be taken after the strings are loosened. The difference between the two measurements becomes my allowance.
Why not calculate my neck reset geometry prior to loosening the strings? Because I will be re-fitting my neck without those strings attached, and it is too easy to miss my target angle when I am just hoping and guessing.
Guild acoustic guitars, particularly older models, are somewhat legendary among repair shops, the consensus being that neck resets are more difficult to perform on a Guild than on other guitars. The Guild brand is among those who did not switch to bolt-on mortise and tenon necks, choosing to retain the more traditional glued-on compound dovetail joint. To reset a neck, it is first necessary to remove it.
Guild necks were first attached to the body, and then the finish was applied. This complicates the removal process and adds the need for touch-up efforts once the neck is re-applied.
The Finish - To remove the neck, the lacquer “seal” must first be broken. After the neck is reset, that lacquer must then be touched up. This can be complicated by a tinted finish, though it isn't a particular nightmare in and of itself.
If, by extreme contrast, you have ever reset a Taylor neck (bolt-on, no lacquer touch-up necessary), you would understand the extra work involved on a Guild neck, along with the additional equipment and skills requirement.
The Glue - If you have reset enough Martin necks you may have run across that occasional instrument where it seems as though you could simply pull the neck off after exhaling a warm sigh across the heel. If you were to then encounter any one of the several Guild necks where any and all open space in the neck joint has been thoroughly flooded with 250 to 300 gram strength hide glue (see the photo example, above), you would likely conclude that Guild neck resets can be more difficult to remove. {snicker}
Some Guild necks are more difficult to remove than others. Few, if any of the ones I have encountered from the 1970s and up through 2010 have ever been as easy to remove as the majority of Martin necks I have removed from the same period. Unfortunately, I cannot provide anyone with an authoritative list of which Guild guitars are more difficult than others, as it remains a mystery even to me until after I have started on a removal.
At issue is the amount of glue applied in the neck joint, and the surfaces to which the glue has been applied. All that should be required of a properly fitted compound dovetail joint is a brush (or fingertip) stroke of glue along the two sides of the tail. The purpose of the adhesive is merely to prevent the tenon from sliding upward in the mortise, the reverse direction from which it was “set.”
The one and only possible reason I can think of for applying copious amounts of glue to a dovetail joint, other than ignorance (not knowing any better), is to compensate for a sloppy fit. So, rather than take the time necessary to correct the actual problem, the loose fit, someone just adds more glue to hold the neck in place.
REMINDER: When I am resetting a neck, to determine how to address the neck heel, I ignore the existing bridge and make my calculations against my target overall string height. If I can achieve that height using the existing bridge (and typically by fashioning a new, taller saddle), great. If not, I make a new bridge.
While this approach is not dissimilar to setting a neck on a brand new guitar, there are additional factors to consider when resetting a neck on an already built guitar, factors that will affect the measurements used to determine how much material to remove from the neck heel. These factors include bellying behind the bridge, sinking in front of the bridge, and shift/collapse at the neck block.
It is advisable to take measurements with the guitar strung to pitch and compare those results with measurements taken after the strings are removed.
For the soundboard measurements, you can use a dial indicator that references the rims. You can also lay a straightedge across the top and note the deviation from a flat plane.
Break the lacquer seal. Remove the 15th fret. Drill the hole(s). Apply the Heat.
Materials, Optimal size
Calculate for material removal
Proper fitting and alignment, glue choices, clamping
Touch-up, drop fill, re-finish
I design and build acoustic guitars. Each instrument is created to be a unique visual and sonic experience.Where a factory may faithfully produce a given model thousands of times, every guitar I make is intentionally distinct. I have written several articles that acknowledge, explore, challenge, and at times defy traditional steel-string acoustic guitar convention.
Gain insight and benefit from my experiences
