First, I transferred the markings to the inside of the spinner. Next I put a new cut-off wheel on my dremmel (one for plastic) and then cut off the lower section leaving about 1/8” to the scribe line. Everything I read on trimming the fiberglass was to leave a little stock on and trim it down later. I then got my thinnest cut-off wheel to cut the sides exactly along the lines. Taking it slow and being careful I was able to make some nice cuts for the straight sections and then cut inside the line for the curves. I came back with the sanding drum on the dremmel to sand it up to the line. I think it turned out well, but I may have to do some more trimming when the prop goes on. I also added the tip bearing piece which too a little while to get to fit just right. Be careful not to take too much off the tip of the spinner to get it flat. Just a couple scrapes with the sanding block went from not nearly enough to almost too much.
