Not much to say about this. When I routed out the enclosed mortises I still had material to remove like with the open mortises. I used a 5/8” forstner bit to drill through and a 1/2” pattern bearing bit to whack out the rest of the material. It was pretty simple. Then I just squared off the corners as usual.
Next job is to make a tenon jig for my table saw and I can move on to making up the stringers and finishing the leg assemblies.
After routing out both sides of the through mortise:
After using the pattern bit to cut out the middle waste:
Squared off the corners of the first one:
No need for a brand stamp for people to know who made this, I left a little DNA behind as payment to the wood gods …