Some guitars have the truss rod adjustment mechanism in the body while others are at the neck. The challenge with adjustments at the body is that strings are in the way if you need to make adjustments past your initial set-up.
Having the adjustment at the neck allows adjustment anytime. With these there are options as well. You could cut the truss rod slot all the way down the neck until it exits the head leaving an aesthetically difficult transition under the nut. This is why so many guitars have the truss rod adjustment cover screwed onto the neck. On the other hand some guitars have truss rod slots that end under the fingerboard, a hole is then drilled from the neck for access. This is the approach I took.
The challenge faced is how to properly locate the hole so that it lines up with the truss rod adjustment mechanism. To address this I used a piece of scrap 1/4″ plywood with a long notch cut out from one side. When the “foot” of the jig is placed in the truss slot, it overhangs the neck and a corresponding point on the other side of the cutout is used to reference both the depth and alignment of the truss rod slot. This is where the drill must begin.
Once the point is marked, clamp the guitar neck to the drill press table set at the same angle as the head was cut. Align the drill bit to the mark and drill away.
