Bill, okay, got it. I went to the next sketch in the Fork and fully defined it. Man, a LOT of dimensioning. That may cause me to sketch in a different way with fewer/simpler curves (already figured that out anyway - can't make a smooth part with lots of curve points).

But all this dimensioning also means it's hard to make fine changes. No going in and just grabbing something to adjust, then close the drawing. I've done plenty of that. Gotta change the dimension instead of dragging the point. Or delete dimensions, drag, then put them back. I see the wisdom of this discipline though.

My Chipmunk model is a mess of interrelationships (many external refs) that would require major rebuilding to modify anything. For example I know the wing incidence is a little off. Even though it will be used by Horizon Hobby to make a flying model, I ain't gonna fix it. I already rebuilt it once to change the airfoil a little and it was a disaster - started over instead of fixing. Guess this is what you mean by blowing up! And of course building assemblies would have been much better too. I wonder if Horizon is even going to be able to use this thing. They may pull out a drawing or two, reference a few curves and start over with their own 3D model.