FLIPOT

There doesn't seem to be an equivalent word for this in English!

A flipot (pronounced "fleepo") is a v-shaped strip of wood used to plug a crack in a wooden object - in this case a 19th. century Viennese guitar.

Thing to do is enlarge the crack with a super-sharp v-shaped chisel attached to a brass foot so that it always remains at the same depth. Then you rub glue into the enlarged crack & shove the flipo in with a soft hammer. BF&I (Brute Force & Ignorance Intelligence).

There's 10x more to it than that, but can tell you I'm pleased with the result