I recently had to figure out how to fit a piece of maple onto the broken out area of this pegbox at the back. Whenever chalk fitting a repair piece, it needs to go back in exactly the same position every time.
Once I tidied up the broken area with minimal removal of original wood, I decided to use a longer piece of wood with the grain following the original that would sit tightly inside the pegbox in the same position every time. I then chalk fitted the end of the repair piece to the original wood.
Before gluing it, I made a couple of small saw cuts near the end to ease the sawing after gluing.
My best tools are all made in Japan and this particular saw was a present from my wonderful friend Michiko Hayashi.