Cutting the "f" holes
I began by laying out the holes from the inside. Measurements were calculated for the acoustic center of the violin. The upper holes calculated to be 38.7mm between. First I drilled the upper and lower holes first, 6.5mm upper and 9.5mm lower. They are drilled 90 degrees to the belly from the inside which finished to 41mm between the upper holes on the outside.
In the inner curve near the lower hole, notice the gouged area called the fluting. It is only for aesthetics.
The "f" holes are not quite parallel to the belly, slightly raised on the lower curve.
Because of the dimensions of my violin, the "f" holes came within 2mm of the purfling at the lower hole.
They turned out nice and parallel with the glue joint.