It took awhile, but the fins are a little different now. The Root-Tip taper wasn't an easy task. The fins taper from .227 to .0625 along a 2.5in span. A little trig gets 1.84 degrees for the half angle.
I knew this would be borderline impossible to achieve by eyeballing my adjustable angle plate in, so I had to resort to using a dial indicator and sweeping along the angle plate.
I just set my indicator to 0 at around the midpoint of the angle plate, moved the Y axis to -2.500 in and ensured my indicator read -80 thou of difference. If it didn't, I used a small hammer to tap it in. Because of the T slots in the plate, the indicator had to reference off of a parallel resting on it.
Another parallel was then clamped to the angle plate and indicated to be true to the X axis movement of the mill.
The fins were then clamped to the plate. I used a 3/4in endmill to cut the angle. I was planning on using a face mill, but I had little trust in my clamping setup. Not a big deal, but the surface finish was less then ideal. I did a bit of a "Clamp Dance" to get every spot on the fins.
After the taper on one side of the fins were cut, I moved onto the other side of the fins. The angle of the plate had to be doubled because the fins would now rest on the previously cut side. I used the same procedure as before, but instead of using 80 thou for my target, I used 160.
After milling, I wasn't too happy with the surface finish. (I think the head of the mill needs to be re-trammed). So I sanded the surface of the fins down on a surface plate.
Nothing special. Just went from 80 grit up to 500. This is a pic after 220.
After the 500 grit, I touched them up on the buffer.
I really should have spent more time getting the deep sanding scratches out and sanding the beveled edges. There's still some deeper scratches and the final pass of 500 is still visible in some spots. (See pics). You could chalk that up to hastiness. The other 3 fins will probably be a little better.
What I was most concerned about is symmetry. Because of the complexity of the setup and the bevels, any errors in the fin's symmetry would be easily visible. Luckily my setup was pretty spot on so as far as I can tell, both sides of the fins are completely symmetrical.
Now onto the harder part.
Alex