Brief Description: Drilled spinner to backing plates
I began by marking the rear of the spinner for mounting holes. The manual says to mark for holes at 5/8” from the edge of the blade cutout. From there I used a flex tape to get the center between the marks, and finally measured and marked the 4 holes between the center and the mark at the blade cutout. Now I had marks for 7 holes per side. I setup a ladder with some blocks clamped to it and a pencil extending forward. Seems like a rather low tech way to center the spinner, but apparently it has been used successfully by other builders. I used 4 cleco side clamps to hold the spinner to the backing plate and began fiddling with getting the spinner centered. I removed the dehydrator plugs from the cylinders so I could turn the prop by hand. After many frustrating iterations, I finally got the spinner centered—at best I can tell anyway. I added 4 more side clamps and checked the center of the spinner several more times. I then drilled four #40 holes thru the spinner into the backplate and checked for center once again—seems ok. I drilled a few more holes, then drilled some holes for attachment to the front plate. The front plate comes pre-drilled and you can faintly see the holes thru the fiberglass. I proceeded drilling until all 6 holes in the front plate and all 14 holes in the rear plate were completed. The spinner is now fixed in position. I left temporary nuts holding the backing plate on. If I have problems riveting nutplates and/or the fillers for the cutouts, I can take off the prop and remove the backing plate to do the rivet dance. If I can get it done without removal, I can replace the temp nuts and torque in place.