I designed mortise and tenon joinery into my next project, which means I am currently figuring out how I'm going to make both. I don't have a table saw.
I intended to make the tenons with a handheld router, a pattern bit (or maybe a guide bushing) and a jig that consists mostly of a board with a rectangular hole in it. In fact, I built a prototype which worked.
But I got to thinking that I'd need to clamp and reclamp and clamp and reclamp and ... you get the picture. One day I had another idea, a take-off on a crosscut sled.
It's basically a sled with a steel guide that fits into the miter slot of my router table. The guide is set into a dado in the bottom of the sled. The sled has a slot down the middle that's the width of the bit (3/4"). It also has an adjustable stop that sets the length of the tenon.
It was pretty easy to build, and so far it seems to work pretty well, with two possible caveats. I need to remake the stop, it doesn't sit quite flat on the surface if the sled, which introduces some imprecision. I knew that as soon as I made it, but I wanted to see if the method would work at all before I improved it. I may also make the stop with thicker stock.
The second caveat is that I have only (so far) tried this method with about a 1/8" depth of cut. But I think it might still be faster to do it this way even If I have to make two shallow passes to remove more material.
It worked nicely at that depth. And quickly too. I wasn't that careful about cutting my test scrap and it came out well. Even the short sides cut nicely. The router bit has a tendency to pull the work *toward* the stop, which wasn't really a problem. I have so far avoided adding toggle clamps; if it works well enough holding the work by hand, I won't.
The one other tweak I think I'll make is to cover the back of the slot with a piece of something hard like maple, so I can't get absentminded and cut into the heel of my hand. That's not the natural place to put either hand, but I try to be safe.