Not shown is drilling out the breadboard with a drill press. Once the hole in the breadboard is driller, fit the joint together and use the same drill bit you plan to use to mark the center point of the hole. Once the center point is established with the center point of the drill bit, you can offset the hole in the mortise by a small amount (depending on the hardness of the wood species and "spring" in the joint). For the purposes of this joint, we sprung the joint by roughly 1/64" and offset the hole by a little more more than 1/16". Mark your center point first.

Make sure you offset the hole so that once the pin is hammered in, it pulls the joint tight rather than pushes it apart!