Another approach that's worked great for me and doesn't require any extra gadgets is to modify the pins for Schleicher ships. The -20 has enough meat sticking out the back of the spar that simply making it more pointy on a lathe works.

I'll try that on the Duo too.

The 27 doesn't have enough extra length for the sharpening process, so I had an insert made that increased it enough to be tapered. A small amount of spar box removal is required to take the extra length.

KS