Time for some fine tuning now.
Still off the saw as you see.
Remember only 50p!
I routered this inside of the cutting edge - so that as the blade gets smaller from repeated sharpening you can drop the depth of the blade so you always have a tight mouth.
Moment of clarity?
My other spokeshaves have mouths that just touch the blade, over time it just gets bigger then you go to do it again - all set up on the router and FLASH the solution appears.
You were working it out all along in your unconscious. Bertrand Russell, my favourite Philosopher of all time - used to use this as a pre-programming technique prior to writing a book or ongoing deep research. Think on your problem really intensely for a short period of time then banish it from your mind for weeks or more. When you come back to it the solution has been worked out many times.