Terry,
There is one thing I failed to fully explain concerning the use of airplane propellers as a loading device. The following information comes from Bolly & was used to prepare the Falcon brand propellers used.
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It is important that propellers be well balanced. The propeller should also sit square to the engine prop driver. Check for an equal height under each tip with the prop sitting on a flat surface.
Many props (especially moulded nylon types) will have an uneven bottom (and / or top) surface due to uneven material shrinkage. Check this before checking for equal heights below each tip.
It can happen that the shaft hole isn’t square to the rear face of the hub, for this it is a good idea to step or taper ream the prop, leaving only a small amount of the hole at the required diameter."
This is the reason I machined the existing hole in the propeller from .3125" to .3750" while clamping the propeller's rear face to a flat indicated surface. The rear face of the Falcon brand propellers are approximately 1.500" in diameter, therefore there is plenty of area to allow clamping.
JA