the base is in a 1/4" x 3/16" rebate glued in place. the traditional way to make a cog was with no glue just dry fitted, then when the bands were fitted it would be filled with water untill the wood had expanded enough to seal all the joints, problem being when the cog dried out after use the bands fell off and the staves collapsed, all my hardwood is dried in an oven to reduce shrinkage so once glued and banded it should be quite solid.