After countless hours of chopping and paring, testing and tweaking, I finally got one of the legs to fit into the top of my workbench.
The next three should go a little more quickly because I learned something very important: trust my layout lines.Rather than sneaking up on the lines and testing the fit of these very heavy boards along the way, I'm going to cut right to them.
Because these legs will need to be removed on occasion, I left a sliver of a gap between the tenons and mortises. I also rounded over the sharp corners of the front of the dovetail slot. Otherwise, they're too fragile and would chip.The joint slides together easily. This being winter with low humidity, I expect that they'll be a little tighter when the weather gets warmer. Nothing a little paraffin wax...or more paring...can't handle.
When all the legs are fitted, I'll trim the tops so they're flush with the benchtop.
This is a more difficult build than I had expected but it's a great learning experience.
And that's what it's all about after all.