On our bench was a very nice ‘71 Gibson SG. At a glance, I could tell this guitar was well taken care of and played throughout the years. It was also pleasant to see that the neck didn’t bear any of the classic war wounds, such as a repaired headstock break or neck joint fracture. This early-‘70s guitar really just needed some major adjustments to be ready to play its part in the next hit song.
This cool-looking guitar has pointed double cutaways and a scalloped mahogany body, two humbucking PAF pickups, four Gibson amp-style knobs, a five-layer black beveled pickguard, ABR-1 Tune-o-matic bridge with white nylon saddles, pearloid trapezoid fingerboard inlays, Indian rosewood fingerboard, neck-body joint at 19th fret (the heel extends to 16th fret), crown peghead inlay, Maestro vibrato with engraved lyre and Gibson logo on the cover plate, chrome-plated parts, a 6-digit serial number and “Made in USA” on the back of the peghead, and a cherry red finish.
Upon inspection, before removing the strings, I noticed that the ABR-1 Tune-o-matic bridge had a concaved look to it. This collapsing effect usually happens over time from the down-angle pressure of the strings coming off the saddles to the tailpiece. This can be avoided at times by raising the tailpiece, which results in less down-angle pressure. It’s possible to correct the chassis section of the bridge to its original leveled surface. The saddle retainer wire, white nylon saddles and saddles screws were removed, and the chassis was now ready to go in our vise with three small strips of wood measuring .090" in thickness— cut from a popsicle stick that we used for spacer material. It really is the perfect stick for the job! Slowly turning clockwise on the vise handle, putting pressure at three contact points, you can see the chassis section of the bridge metamorphose to its original state.
Spacing After the frets and fretboard were cleaned and polished, the strings went on and the string alignment was checked out. The nylon saddles were never slotted and needed to be for optimum tone and tight string attack. The outer two strings were first positioned, marked and slotted using nut files sized to the correct string gauge. Then, the inner four strings were evenly spaced apart using my Luthier’s Digital Calipers, and slotted into position as well.
It was time to address the curvature in the neck. I like using my Neck Relief Gauge for this job. There’s no more need to eyeball your work, as it tells you exactly where you are. With this tool, one foot rests on the crown of the first fret and the other foot on the 12th fret. The dial gauge then takes a reading in thousandths of an inch over the fifth fret. Generally, I like to see the gauge read .008 after the frets have been freshly dressed. When the frets are slightly worn or at a level of stock performance, we may need to increase the relief up to .010.
These Gibson amp knobs just wouldn’t stay on anymore and kept slipping off the shaft of the pot. What we did not want to do was bend the two stems apart on these original early-‘71 pots because they’d snap right off. Using 1/4" wide black paper pickup coil tape and daintily wrapping around the outer diameter of the split shaft worked miracles. As the tape conformed, the knob flowed on perfectly and grabbed once in position.
For this month’s restoration, I used the following tools and materials, available at stewmac.com:
#1820 Angle Vise
#5212 Luthier’s Digital Caliper
#0821–#5313 Gauged Nut Slotting Files
#0825 File Cleaning Brush
#4894 6" Steel Rule
#5893 Guitar Nutdrivers
#6106 Pocket Truss Rod Wrench
#0353 Understring Radius Gauges
#2004 Neck Relief Gauge
#5027 DeoxIT Pot & Switch Cleaner
#5951 Pickup Coil Tape
As always, it’s a pleasure sharing another adventure in “Restoring An Original.”
John Brown, of Brown's Guitar Factory, is the inventor of the Fretted/Less bass. He owns and operates a full guitar manufacturing and repair/restoration facility, which is staffed by a team of talented luthiers. He is also the designer of guitar making/repair tools and accessories that are used today by instrument builders throughout the world.
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