Thanks guys. I mostly used or tried to use the Delta Mortise attachment to the drill press but I had real difficulty getting the sides of the mortise smooth. The flexing of the hollow chisel or my poor alignment kept me cleaning out the mortises. The last few I did by hand. Very satisfying and came out better.
As for changes, I do not know. I was focusing on getting this right that I did not think of how to design it better.
I would change how I made it regarding the mortise attachment but that has been covered extensively in another post.
Also, this has been a lesson in how tough White Oak is.