Here is the process for cutting the tenons for my timberframe shed. I used a combination of hemlock and white pine. Basically, my choices were based on whatever I had leftover from building my workshop. When I built the workshop, I tried to use the pine for posts (which mostly get mortises) and the hemlock for beams (mostly tenoned). The pine is much easier to cut mortises into and the hemlock offers more strength for beams.
Here is my homemade marking gauge. The center spur was helpful when I used to drill out my mortises with a 2 inch forstner bit.
Here I have used my circular saw (my first powertool, now approaching its 20th year of service!) to kerf to the proper depth around the tenon.
After knocking off the waste, I cleaned the tenon up with my slick (think large chisel that cuts like a drawknife). This was a particularly gnarly piece of hemlock and didn't give the prettiest results, but they'll be around long after I'm gone.
Here is a view from the top of the tenon.
With the help of my friends Bill and Rich, I erected the structure the other day. There is something amazing about seeing the whole thing raised in an hour or so. While working on the frame, I kept thinking, "this will be the last timberframe I do" but once it was up, the simplicity and grace of the frame has me looking forward to the next one. Whenever building with mortise and tenons in the standard table and cabinet size, I suppose we believe in their utility because we are told to. How often are we around to see the true benefits of the extra effort to create solid joinery? But in a timberframe, there it is, push with all your might and the joints answer back with a strength that resounds. So much of woodworking seems to be about pursuing the expectations of strength and quality that I cobble together from a myriad of influences, I find that the simple strength of the timberframe is an answer in itself.