Interestingly enough, this mark on the edge of the cavity is no longer present on any Les Pauls manufactured after 1960, as new equipment was acquired and eventually manufacturing facilities moved to Nashville, Tennessee.

But even though this arcane detail may help us authenticate an original 1950's era LP, unfortunately, forgers also know about this and have been known to recreate this detail in fine quality fakes. Nothing beats provenance when authenticating a guitar.

According to manufacturing experts inside and outside of Gibson, all Les Paul Standards made between 1952 and 1960 used the exact same routing machine. When the time came to drill the hole for the stem of the bridge volume pot, the drill bits upper surface would create this mark as it rubbed against the outer edge of the cavity. Some say this may have occured because the thickness of the guitar is less for the bridge volume pot stem hole than for any of the other pots due to it's location on the guitar.

1957 Les Paul Control Cavity

1968 Les Paul Control Cavity

1952 Les Paul Control Cavity

1953 Les Paul Control Cavity

Now looking at the following three photos of later model Les Paul cavities we can see that the characteristic mark found on the outer edge of the bridge volume pot portion of the cavity, is no longer present.  Later models have one continuous and smooth cut around the entire edge of the cavity.

2012 Les Paul Control Cavity

What in the world is Router Chaw? Sounds like it could be a new band! But in fact, it's a relatively obscure known manufacturing detail specific to all Les Paul Standards made between 1952 and 1960, where in the cutout beneath the bridge pickup volume pot always has an extra cut along the edge of this part of the cavity.

Viewing the photos below, you will be able to see a consistent mark along the edge of the lower left cavity of the bridge volume pot.

1958 Les Paul Control Cavity

1954 Les Paul Control Cavity

1990 Les Paul Control Cavity

1958 Les Paul Control Cavity

1955 Les Paul Control Cavity

 Vinasco Vintage Guitars

Because Guitars Are Cool.

1960 Les Paul Control Cavity

1956 Les Paul Control Cavity

Router Chaw