This jig maintains 35mm (1-3/8") hole spacing for steel-string guitar tuning machine string posts or classical guitar machine rollers. The jig is self-centering and maintains constant hole spacing on any peghead thickness between 1/2" and 1-1/8". Reducer bushings are supplied for drilling the smaller holes required by steel-string tuners. Drill bits for steel-string and classical tuners are also included.
For classical tuners
Remove the reducer bushings from the jig. Line up the three holes in the jig with the hole locations you have marked on the edge of the guitar peghead. Sandwich the peghead between the two 3-1/2" x 1-1/2" plates of the drill jig, and clamp it in place. This automatically centers the holes on the edge of the peghead. Be sure the jig is properly located and is resting on the edge of the peghead.
If the peghead has already been slotted, we recommend making close-fitting temporary wooden spacers to fill each slot during drilling. This will help prevent splintering on the inner walls of the slots.
Use the 13/32" drill bit through the fixed bushings in the jig. Wrap a bit of masking tape around the drill bit to indicate when the drilling has gone deep enough. You can use a hand drill or a drill press. Repeat the procedure on the other side of the peghead.
For steel-string tuners
To drill for steel-string tuners, the reducer bushings and the "G" (0.261") drill bit should be used. Insert the bushings so that their collars are on the outside of the jig, and secure them in place with the button head cap screws (1/8" Allen wrench required, not included). The locating and drilling procedure is the same as for classical tuners.
In normal installation, the jig will locate the holes along the centerline of each peghead edge. To drill the holes off-center, place a spacer shim between the peghead and one of the clamped aluminum plates, on the side that the hole is to be moved toward. Adjust the thickness of the shim for the desired amount of movement.