I was looking at that too. He certainly took off a lot of material. I think that he had the same issue that started me thinking about the Windsor balancer - the prop shaft hole was drilled off center.

Also, if you watched W8YE's video in Post 9, in the first 20 seconds you can see where the prop tips don't track when you rotate it - that tells me that the drilled prop shaft hole is off center.

Presuming that the wood or composite is relatively homogeneous throughout the prop, re-drilling a trued-up prop shaft hole would cure these problems. Of course, this presumes that you're using a drill press with the table square to the drill bit, a flat-bottomed drill (or a mill) and the prop is anchored so that it doesn't wander.

I wonder if something like the jigs for that Windsor balancer could be duplicated?

Bob