Building a cabinet-type box, 3/4" birch veneer plywood. Wanted the floor of the box to sit in a dado in the sides, so grabbed my Whiteside undersized plywood router bit and cut a nice dado. Floor fits snugly into the dado. All is right with the world.
Until I went to glue it up.
I glued the dado - sides and back -- and a little glue on the sides of the floor that was to go into the dado. Before I could get them together, they swelled up and made it all but impossible to join the two. I ended up frantically pulling them back apart, trying to clean out the glue, waiting for it to dry and hitting both pieces with some sandpaper to try to make the fit a little less tight. Eventually got them glued up, but had to pound a lot harder with a mallet and block of wood than I think I should have.
What did I do wrong? Should I have put glue only in the bottom of the dado and edge of the floor piece?