ON THE BENCH by John M. LeVan
Intonating a 1960 Gibson ES-335 Correcting the Intonation using a shelf nut.
Recently, one of my clients brought a beautiful ES-335 into my shop. This ES335 played and sounded fantastic, but would not play in tune. It would (somewhat) intonate at the 12th fret, but the notes in first position were dreadfully sharp. My client is a studio player, so I needed to find a solution that wouldn’t devalue the instrument. Figure 1 1960 Gibson ES-335. EVALUATING THE GUITAR The guitar is a 1960 Gibson ES-335 in excellent condition. When evaluating a guitar, I always look at the condition of the frets, string nut, and bridge. These components have a profound effect on the intonation. In this case, all three were perfect! So what could possibly cause this amazing guitar to play so horribly out of tune? I suspected the string nut was in the wrong location. If the nut is too far away from, or too close to the first fret, the guitar will never intonate properly. After measuring the scale length (with a micrometer) and processing the measurements using the rule of 18, I found that the location of the string nut was .027” off. Now .027” doesn’t sound like much, but on a guitar it’s a mile! The task at hand now became figuring out a way to move the string nut closer to the first fret without permanently modifying the guitar.
current location of the string nut was 1.410”, it should be 1.3831”. After all of the calculations were checked and rechecked, I was ready to correct the location of the nut. RELOCATING THE STRING NUT
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Figure 3 Carving the shelf nut.
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Figure 2 Measuring the nut placement.
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Figure 4 Shelf nut in process. After restringing and adjusting the intonation, this 335 finally plays well in tune and is now studio ready! If you have any questions about this, or any of my other articles, feel free to e-mail me at guitarservices@aol.com. Be sure to visit us on the web at www. guitarservices.com John M. LeVan The Guitar Services Workshop www.guitarservices.com
Here is what the formula looks like: Scale = 24.642” ÷ (rule of 18) 17.817 = (correct location for nut) 1.3831”. The
Using an oversized piece of bone, I removed material from the nut so that it fit into the slot and extended over the fretboard. Once the nut was fitted, I gently sanded the face of the nut until it was the correct distance from the first fret. From there, I carved the string slots and contours to the back and sides of the nut. I colored and polished it to give it a vintage look. This process is easily reversed and undetectable.
Figure 5 The new shelf nut.
THE RULE OF 18 This is the standard unit of measurement to determine the correct placement of the string nut and frets. I measured the scale length of the guitar from the face of the string nut to the top of the 12th fret. Then I multiplied that by 2. That gave me the exact scale length of the guitar. Then I took that figure and divided it by 17.817 (the rule of 18). The quotient (result) of this equation is the theoretical distance from the string nut to the top of the 1st fret.
Typically, I would remove material from the end of the fretboard. However, since this is a vintage Gibson, the last thing I wanted to do was to modify the fretboard. Cutting the fretboard would devalue this guitar! The best solution was to carve a shelf-nut. A shelf-nut is a string nut that has an extension over the fretboard (moving the nut closer to the first fret). I carve these out a single piece of bone so that it will last as long as a traditional string nut.
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Copyright ©2013-2014 John M. LeVan all rights reserved. Photos by John M. LeVan.