In the previous installment, I cut the dado for the housing, marked out the shelf tenon, and cut the tenon cheeks. The next step was to cut out the long shoulders:

It’s a little bit difficult to do this with this backsaw because it’s not deep enough to finish the cut, but I found that if you go as far as you can diagonally on both sides, it’s trivial to finish off with a coping saw. Something like a ryoba or thin panel saw would also work.

Here’s how the end of the shelf looks when trimmed and finished:

Now the slightly tricky part: marking and cutting the mortise for this little tenon. To mark, I put the shelf into the housing, registered where it needed to be registered, and used a lead holder to mark the lines at the bottom of the housing:

(However difficult this may look, it turns out that taking that photo was the most challenging part of this project so far.)

Then I removed the shelf, cleaned up the marks I had just made, got out the pigsticker, and started chopping away (but not too violently, since it’s not a through tenon):

Some paring was necessary to clean up the sides and bottom, as you’d probably expect.

That’s pretty much it. In the end, these were the final components:

And here is how it looks in a test-fit:

I also made the other three of these joints for the bookshelf prototype project today and did a test assembly. However, I’m not ready to glue up yet. There’s still a matter of the panels.