Measure the diameter of your tuner's mounting nut (shown at the
right); this is the required tuner hole diameter, which is quite
likely to be 10mm. Drilling the tuning machine holes is usually
done on a drill press but can also be done by hand.
To ensure that the holes are perpendicular to the peghead surface
and to get the alignment and the distances between the holes right,
I used a self-made drilling jig. It consists of a 2x2x6"
(50x50x150mm) hardwood block with three 10mm holes whose centers
are 1-5/8" (42mm) apart and 13/32" (10mm) from one long
edge. I have to admit that I went to a drill press for making this
jig. A guide made of plywood glued to one side makes it easy to
correctly align and fix the jig on the peghead.
The middle of the first tuner hole should be located 2-3/8"
(60mm) from line "B". Position the jig and remember to
put a backing board on the back of the peghead before fixing the
jig with two clamps. Make sure that the clamps stay clear of the
tuner holes.
When using the brace I stabilize it by laying my chin on the back
of my left hand. I drill with very little downward pressure and let
the bit do the work.