I intended to demonstrate cutting the large leg tenons for the Roubo workbench build two different ways: by hand and with the aid of a band saw. Unfortunately, my camera shifted while I was cutting the tenon cheeks. Consequently, you’ll only get to see my poor cross-cutting skills today.
I like to start by marking out my shoulders. I prefer to do this using a square against the long grain, as opposed to using a cutting gauge against the end grain. I get more consistent results. I hold the square using my thumb against the stock and one or two fingers on the blade. Make sure that you draw straight back with your knife. Start with one or two light cuts, and gradually increase pressure. Flip your piece, place your knife in your previous line, reference your square off of your knife, and repeat. Always make sure that you are referencing your square off of your face or face edge.
Once I have my shoulders marked out, I move on to the cheeks. I use a simple wheel gauge for the cheeks. I set the fence and give it a couple of quick passes for each side. There really isn’t much to describe here. When I’m finished, I like to darken all of my lines with a mechanical pencil.
Cutting the Shoulders
With the marking out-of-the-way, I move on to the shoulders. In the video above, I am using a small backsaw. Before I start sawing, I make a little trench on the waste side of my work piece with a chisel. This gives my saw a little groove in which to ride.
I start by drawing the saw back a few times. This deepens the groove, and helps ensure I stay on track. Next, I take a few light passes on the far corner, and lower the saw plate until I’m taking cuts across the entire width of the leg. At this point, I saw down to the baselines at the corners to make sure that my cut stays square. I finish the cut by removing the triangle left in the center.
Cutting the Cheeks
This is the easy part. I believe this is the best way to cut tenons. If you have a band saw and haven’t given it a try, what are you waiting for? Simply line up the fence to the waste side of your line, and go. Cut down to your shoulder line, flip and repeat. It’s fast, easy, and produces a nice square cut (assuming you set up your band saw properly).
With the waste removed it’s time to start cleaning up the shoulders. The band saw produces square cheeks right off the saw. I will mark the mortises directly from the tenons. There is no need for them to be identical, only need square.
Use a chisel and deepen your knife line on all three sides of your shoulder. Then, take over-lapping passes from on side to the other using your knife line as a reference. If you’ve left too much waste, you might have to take a couple of passes. It’s easier than trying to remove 1/16 or more in a single pass. Check your work with a small square. I undercut mine by a few thousandths.
Stay tuned. Mortises are next.
You can find links to my other Roubo posts here: Project Index
Music: Good Old War – My Own Sinking Ship