Fabricated John's design today. With the digital level this fixture is repeatable down to 0.05 to 0.1 degree. A very good design!!
Works MUCH, MUCH better than the plastic prop protractor that many are using.
I checked my prop, blade to blade and was SURPRISED! Will be making an adjustment.
Took me about 4 hours to fabricate the tool. One suggestion, before riveting the two end pieces, ensure you fit the tool to the blade and ensure both end pieces contact the blade at about the same point. You will find there is an offset due to the twist in the blade.
And when making a measurement, ensure the blade tip is the same distance from the hangar floor after you rotate it. And of course, the tool has to positioned at the same spot. Use the stripe on the blade as your reference.
A very GOOD idea!