Classical guitars and steel string guitars with openwork headstocks usually have leg shaft machine heads with a hole spacing of 35mm. Making these freehand is quite tedious and risky. This device is intended to remedy the situation. On two mounting plates there are three lugs with drill bushings on them. The borh bushings are connected to the mounting plates by two screws each. If you now fasten the mounting plates to the guitar head with screw clamps, the drill bushings keep the correct distance from each other and ensure secure guidance of the drills.
The same tabs are designed so that, mounted on two tubes, they can also be used for electric guitars or other guitar machine heads to be drilled horizontally. Photos for this follow.