Ken's back playing luthier (that's what he calls it) after weeks of travel. He sent some pictures and an update. He routed the neck tenon tonight.
Here is Ken's commentary followed by his pictures:
"This is a trickier process that one may imagine. The angle of the neck where it attaches to the body is what determines the action. I have a jig I made to route both the mortise and tenon. To cut the tenon, the neck is mounted to a vertical table that swings a few degrees outward. I put the body of your guitar on the surface then set a determined gap between the saddle location and the plane of the surface the neck is mounted to, by tilting the neck surface a few degrees. Once I have the gap I want, I lock the surface down tight and use a template to route the neck tenon.
To minimize tearout along the shoulders, I run a strip of tape along each side."
Thanks for looking-
Beth (for Ken)