1 Locate the bridge on the top

The ideal: The first three steps in fitting a bridge are concerned with deciding where the new bridge will sit on the top of the violin. Ideally it will be centered between the ff-s, inline with the f-hole nicks, which will themselves be located 192-195mm from the upper edge of the violin.  Ideally the bass bar will be located about 1mm inside the bridge foot (step 2) and the neck, which follows the centerline of the instrument, will point straight at the bridge (step 3).

Reality: On a new instrument these ideals will be met, but on an old instrument other design ideals, poor execution and distortions caused by age conspire to force compromises. In addition instruments are idiosyncratic and an apparently whacky set-up may be the result of a long process of trial and error by a previous violin maker.  It is wise to consider the existing set-up carefully before imposing rule book measurements.

in this picture the bridge is centered between the f-holes and its position is marked with tape.