Use your head when boring mortises
Just a quick tip when boring mortises: Have some type of visual reference and be sure to be in the proper reference plane when boring.
(That’s an old Spofford brace, just doesn’t get any better.)
Use your head to stabilize the brace while boring. (Of course, make sure that your feet are positioned in such a way as to create a stable platform.) A colorful, yet tasteful bandana will add to your accuracy (by keeping the perspiration out of your eyes). Be sure to keep both eyes open, just like when you’re shooting. Looking through one eye can create a false reference. Count the number of turns it takes to get down to the required depth.
You’ll be surprised how quickly you can rough out big mortises with a brace and bit. A little clean up with a large register chisel and you’ll be ready to fit the tenons.
This technique must certainly be the basis of the old expression, “now that’s using your head!”.