The Panther main gear was set up on 5-1/4” tall wood blocks and the rear fuselage on a saw horse to stabilize the plane for fitting the propeller spinner. This enabled me to turn the propeller slowly without changing the airplane’s position, without removing the sparkplugs.
The propeller hub and spinner bulkheads were mounted with hardware store bolts. The spinner was set in position and after some finagling, I was able to reduce the run-out near the tip to ~0.016” total. There didn’t seem to be anything I could do to get it better than this. The spinner is not perfectly round, and it turned out that the cut on the rear of the spinner was not perfectly perpendicular to the spinner axis.
The screw holes through the spinner and bulkhead flanges were initially drilled to #40, then updrilled to #30. 8-32 nutplates were clecoed on the outside of the spinner flanges, and their rivet holes drilled in the flanges to #40. The center screw holes were then updrilled to #19, all the holes deburred, and the nutplates were mounted on the inside of the flanges with screws through the center holes. The nutplates were riveted in place, and the holes in the spinner updrilled to #19.
Everything was cleaned up, and the spinner was mounted with the screws supplied with the spinner by Vans Aircraft.
The engine was run and there was no obvious run-out on the spinner except at the back edge. This edge will be re-cut to align it parallel with the back edge of the rear spinner bulkhead.