The patent for Gibson’s adjustable rod was filed on April 5 1921 and issued on February 27 1923. Invented by Plant Manager Thaddeus McHugh, the device was installed in all Gibson guitars – with the exception of the L-Jr – from late 1922 (exceptions include some early flattop models and guitars that were built during World War II).
Truss rod position
The truss rod was a feature of the L-5 from its introduction and its position on the headstock can help date a guitar or indicate whether the neck has been replaced at some point. All Loar-signed L-5s have a truss rod cover that is positioned comparatively high on the headstock face. By the early 1930s, examples begin to appear with the truss rod cover positioned noticeably closer to the nut. This isn’t consistent however and L-5s can still be found with the truss rod cover in the higher position into the mid 1930s.
The position of the truss rod pocket and cover are an indication of how deep the channel was cut for the rod itself. Since earlier Gibson necks were quite large, the rod needed to be set deeper. This resulted in the then-typical position of the cover, away from the nut. When Gibson moved to a slimmer neck profile, the rod channel wasn’t cut so deep and as a consequence, the pocket was repositioned closer to the nut.
The earliest truss rod covers were a simple bell-shaped black plastic affair secured by two slot-head screws. The design remained more or less the same until the introduction of the Advanced L-5 in 1935 when a bold white border was added.
Abalone truss rod covers
“I believe that Gibson initially intended the L-5 guitar and the F-5 mandolin to have an abalone truss rod cover,” says vintage instrument authority Darryl Wolfe. Examples include the earliest F-5 mandolin as well as the L-5 guitar pictured in Gibson’s catalogue 0 (issued in late1924/early 1925) and the F-5 mandolin seen in catalogue N (c. 1923).
Custom Truss Rod Covers
During the pre-war period, an L-5 (or other Gibson instrument) could be ordered with a truss rod cover that was personalised with the owner’s name. The engraving may have been done by William C. Schrier, who was employed by the Henderson-Ames Company (which designed and made uniform regalia) as an etcher and engraver. From 1928 to 1931 Schrier did additional work for Gibson from the basement of his home in Kalamazoo and besides engraving truss rod covers, may well have been responsible for etching Gibson’s Florentine, Bella Voce and All American banjo fingerboards.
One of the best-known examples of a personalised truss rod cover is the pearl item that appears on the iconic L-5 that belonged to country music legend, Maybelle Carter (serial number 85558). Over the years Maybelle’s guitar has undergone several modifications and now sports a later tailpiece and tuners. The pearl truss rod cover – which is engraved ‘Mae Belle Carter’ – was already in place in early photos that show Maybelle with the guitar, suggesting that it is indeed factory-original.
Mono-Plak metal truss rod covers
It’s worth mentioning here the metal truss rod covers that are occasionally found on older Gibson guitars. Though often thought to be original equipment, these were in fact manufactured by the ‘Mono-Plak’ company and added to the instrument by the guitar’s owner. Available for guitar, banjo, mandolin and ukulele, they were offered in three versions; 14-carat gold-plated and nickel silver-plated, both priced at $3.00 and a sterling silver option that cost $8.00. The price included free engraving of “eight letters per line” with a limit of two lines. Additional letters cost 15c each. The item was ‘gift boxed’ in a Lucite case.
Thanks go to the late Paul Hostetter for information on the positioning of the truss rod pocket and cover.