Bill Tindall, E.Tn.
If after a bit of practice if you are not finding making this joint easy there is some detail(s) you haven't discovered. In that case call or write.
When I took the Headley class, Jeff began setting up machines to make these joints for the class participants. Steve was walking by and was asked how it was done in 1780. He retired to his bench and returned with the angled guide block. He described the process. I had my joints done before Jeff completed machine set up.
Shown is me making my first joint