Under The Knife
As a last resort, Alex Bishop prepares to operate on a vintage Yamaha acoustic – but will it recover from the ordeal?
Repeatedly, old Father Time has proven to be an enemy of so many instruments; the unrelenting tension of taut steel strings will so often gradually buckle soundboards, warp necks and twist fingerboards beyond the realms of playability. While it’s often the case that a thorough setup by an experienced luthier may rectify these problems, replacing frets, levelling fingerboards and crafting a new nut or saddle may not always be enough to fix a guitar when its carefully aligned geometry has been pulled out of shape by the malevolent forces of time. A new beginning is required; the guitar must be subjected to an emergency procedure.
Like a nervous surgeon on the day of an important operation, the true test of any aspiring guitar repairer is surely the daunting task of performing a ‘neck reset’ for the first time on a valuable vintage acoustic guitar. The 1970s Yamaha FG-140 on my workbench this month needs precisely this work and – while this isn’t exactly my first rodeo – a neck reset must always be approached with caution.
Essentially, this is the scenario: the combined pull of the strings on the guitar headstock and the soundboard can cause the instrument to pull up at each end, causing the strings to be too high from the surface of the fingerboard along the neck. Attempts to shave the bridge down or crank the truss rod may have already been made at this point, so the last resort is to reset the neck angle. This brings it a degree or two towards the back, both lowering the height of the strings and permitting a higher saddle, which will noticeably improve projection and tone. Well-aged and lightly built guitars are the most prone to this unfortunate demise, so it’s often the finer-quality vintage guitars that end up under the knife for this kind of treatment. However, the invasive process of neck removal can be devastating if it doesn’t work out.
To remove the neck, the first stage is to detach the tongue of the fingerboard from where it joins the soundboard. This is done by warming up the glue join (I like to use a heat gun) and tentatively probing with a sharp, broad palette knife. I am always mindful of the direction of the grain of the top; spruce in particular will easily tempt the blade into deviating from the join, driving it down through the softwood top instead, causing untold damage.
Separation Anxiety
Once I’m confident this is complete, I pluck the 15th fret from the fretboard. It so happens that a cavity between the join of the neck and body lies beneath this position, which can be verified by drilling a small hole (no bigger than the width of the fretwire) through the slot. Into this a thin hollow needle is inserted, attached via a hose to a steam cleaner. This device works great as a controllable source of hot, pressurised steam for injecting into the join. The glue gradually breaks down and by working the neck back and forth, further heat and moisture permeates across the join until – voila! – it separates and the neck is freed from the body.
Refitting the neck comes next, which is a much more delicate process compared with the hissing steam and cracking joins involved in its brutish removal. Razorsharp chisels and precision knives are employed to gently pare away wood around the base of the heel. Dependent upon intricate woodworking and patient craftsmanship, the newly fitted neck must dovetail perfectly into the body at precisely the correct angle for optimum playability.
It’s hard to be completely confident that the procedure has worked until the guitar gets its strings on for the first time. It only takes a few chords for me to realise it really sings; not only does the guitar possess a powerful new voice but it does so effortlessly, my fingers barely registering the frets as I explore the fretboard. Its life extended, I conclude the procedure has been a success. Let’s hope it enjoys another healthy 50 years before we meet again.
“The true test of any aspiring guitar repairer is surely the daunting task of performing a ‘neck reset’ for the first time on a valuable guitar”