Some questions were asked on Google+ in regards to the reason the 1/8" rabbet was cut on the bottom side of the tails. First, this is a trick made popular by Chris Schwarz and not something I came up with. The 1/8" rabbet makes it much easier to lay out the pins since the tail board has a ledge to reference. The rabbet also helps keep the case square. Also, with a case this large it affords the use of clamps to hold it all in place while marking.