I saved all Saturday just for the mortises. Four inches deep, 2" wide or thereabouts. Ouch.
So I wimped out and got my trusty hand drill out with the biggest bit in my arsenal, a 1/2 incher! It went pretty quick and I could use my brace to chew out the interior and then pare away the rest with my chisels
First time I tested fitment of the legs into the mortises, they got wedged in REALLY TIGHT, and no amount of huffing could get them out. I knew I had a scissor jack in the trunk of our car, but in a fit of laziness located a two boards near by, and FORSOOTH, a FIRST CLASS LEVER was born!
it actually worked pretty well, I could lift the trestle up, shove a couple boards under the tennon shoulders on one end, and then creep the other side up in a similar manner. I only had to do this about 57 times before the fit was working.
The next step was to figure out how to drill in a reasonably accurate way. A couple years ago in a stupor of inaccuracy, I grabbed a doweling jig at the local hardware store. These things are absolute junk for doweling, but the one I had had a nice metal index for the drill bits that I remembered. So I harvested it from the jig assembly and clamped it to the walls of my benchtop like so. Worked pretty well, and I was able to then use the same approach to place the holes for the tennons with a tad of offset in a reasonably predictable manner:
After attaching the legs, it was time to flip it over onto its feet.
Sarah implored me to wait for some house guests to arrive to help with lifting this thing (we were going out to dinner this evening). But I couldn't wait for them, and I could not lift the thing on my own. So I decided to use my dolly like so as a second class lever:
And I was able to get the bench on its side pretty easily like this:
Pause to drill some 3/4" holes for work holding pegs to support material during edge work.