Checking in with a progress update, and a couple of questions for you guys. Sorry for the long-winded post...basically I just need your opinion on the looseness of the MT joints. They will be keyed (tusk tenon) so the table base can knock down.
So first off, this was more time consuming than expected - and definitely a case of "the tortoise wins the race". I'm glad I did it though and look forward to doing a better job next time!
I went with the drill press method using a forstner bit from both sides of the through mortises. I drilled the corners using a longer brad point - the exit holes served as alignment marks for the opposite face. That all worked well enough. However, after a series of "learning experiences" while paring the mortises to their final size, I wound up with looser joints than I'd like. The insides of the mortises aren't perfectly flat or parallel to opposite faces and there are gaps in the joint as a result (both visible and hidden). I would guess the gaps average 1/16 to 1/8", but inconsistently, so I cant just insert a thin shim
I've attached photos showing how the looseness translates into unconstrained movement of the legs. They can be rotated several degrees before encountering resistance (compare photos 2,3). The entire base can be "racked" such that the top would move a full inch before resistance (photo 1).
What do you guys think? Should I consider enlarging the mortises (accurately this time) and either cutting new tenons on a new stringer, or reinforcing the tenons on the current board by laminating new material onto them? If so, what's the trick to enlarging the mortises by abouy 1/4" all around? My biggest difficulty was using a chisel to pare away the scalloped edges left by the forstner bit, is that something that just comes with practice or was I using bad technique? I held the chisel vertically and tapped it with a hammer. Used a 1" wide chisel. This is knotty oak and I kept my chisel as sharp as I could, but it was still gouging and tearing the fibers and trying to follow the grain. Crappy chisel?
I'd really appreciate your advice! Worse comes to worse I'll simply add diagonal reinforcements to constrain racking, and a 1x12 across top of the base to constrain rotation. But I'd be much happier if I can improve the fit of the keyed mortise and tenons!