You were right sir, I was able to fix the geometry and now the subtract is working! Thanks! Bill

It would be a really nice feature to have Sketchup manage the accuracy problem by automatically scaling up the geometry so you don't have to worry about it. Enter and display dimensions as usual but behind the scenes it's all scaled up by 100x.

I've made some progress. I learned how to import a real airfoil with a non-zero thickness trailing edge (NACA 0006) and loft it into a simple fin shape. Then I used the technique in the video to make a fillet. It's pretty good and I'm going to close this thread. Thanks for the help cotty! [image: XWcR_FinfilletalaCurviloft.png] Fillet 2(v6).skp

@blackcat1313 said: One thing, my installation has a _46 folder, not _45. Is that going to matter? _46 is Ok, as this is the last version. Fredo