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I've been doing some shaping of 1/8" basswood fins lately. Differences I have discovered, relative to balsa:
1) You can go one grade coarser than 220 grit to do initial rough shaping. I have been staying with 220 though, because by working slowly I'm less likely to oversand anything. I seldom go coarser than 400 with balsa, unless it's very hard.
2) You don't have to handle the wood pieces like Faberge eggs. Almost every time I handle balsa fins I put an inadvertent fingernail mark or some other ding in the wood. Even while applying significant force with 220 grit to shape it, I find I don't need to worry too much about dinging the basswood. That is *very* nice.
3) As an addendum to #2, it seems like it'll hold a fairly sharp edge with no problem. I might harden the edges with CA at the end, but honestly it seems like it will only matter for fin edges that are likely to absorb landing impact.
4) Indeed it sands very smooth. In my correspondence with John Pursely, he has stressed that basswood sands best with the grain. I've been doing a round of 400 grit and then 800 and end up with a pretty smooth piece of wood.
Overall I've enjoyed working with it a lot. Might use it more in the future. I think 3/32" would be my preference, but that is less easy to find locally (I think Hobby Lobby has it).
I like basswood and reserve it for special uses where strength is a consideration (glider fuselages and wing leading edges, rotor stops, etc.). You're right that basswood won't crush like balsa. Just a little too much of a squeeze and balsa smushes. (I'm notorious for doing that to nose cones. Fortunately I've discovered that with the small dings/dents, a tiny bit of water applied to it will pop it back out as it absorbs the moisture). Also balsa is very much affected by humidity where basswood isn't. Balsa seems to be a moisture sponge and it plays havoc with gliders after you've tediously trimmed one and you suddenly have a really humid day.
The only reason I made these replacement rotors out of basswood was because I was upset after the balsa version snapped and it took me forever to get the broken one unglued from its hinge. I think basswood is about 20 - 30% heavier than balsa but since my main concern is longevity and not altitude or duration like in a competition model, it's not much of a concern.