Not necessarily, Jim.

I was thinking to route out the areas NOT in contact with skin and
gussets, leaving the areas where other parts will be in contact.

On the Flybaby, for instance, one might be able to do the routing
after assembling the framework. But my origonal thought was to
lay out the pieces, mark off the areas to be routed off (sorry -
chamfered!) then assemble and glue together.

But the 80 grit grinder is probably as good an approach as what I was
thinking. Take less fore-thought anyway.

Having said all this, I'll point out that the only wood airplanes I've
ever built used 1/16" balsa sticks. Probably not feasible there...

Thinking too much?

RIchard