Master the Mortise & Tenon

I use a traditional European bowsaw to cut the tenons by hand.

I use a traditional European bowsaw to cut the tenons by hand.

Set the two cutters of your mortising gauge to the thickness of the chisel, as shown at left, then move your fence so the cutters are centered in the stretchers and mark them.  Do the same with the seat rails. Reset your marking gauge and mark the legs. Make sure you are in the middle. Clamp the leg to your bench and start chopping. Stay away from the pencil line and take 1/8″ chips. Keep going deeper and pry out your chips. When you are halfway through, do the final cut on the line. Turn it over and do the same from the other side. You can clean your hole with a rasp.

For the tenon, I use a bowsaw, as seen at left. I clamp the pieces in my bench and cut them making sure I am on the line. If you do not have a bowsaw, use your tenoning saw. I cut on the waste side, leaving the tenon snug. To cut the shoulders I use a dovetail saw, as seen in the center photo below. I bevel all four sides of the ends of the tenons with a chisel. Try the fit and adjust with the rasp and chisel until it is just right. It should be tight along the width, not from end to end.

An alternative to the bowsaw is a tenon saw, filed for ripping.

An alternative to the bowsaw is a tenon saw, filed for ripping.

Mortiser and Table Saw
To mortise with a hollow-chisel mortiser, mark your legs the same way. You do not need a marking gauge; the machine’s fence will set the chisel to the middle, as shown below right on the facing page. The hollow chisel should be set so that the drill bit has a credit-card thickness gap at the bottom between the chisel and the end of the drill bit to leave room for the chips to go up and not run hot. Mortise halfway, flip it and mortise from the other side. This way you have clean openings.

To tenon on the table saw, I use my tenoning jig, which fits on the table saw fence. Mark a scrap with small lines for the width of the tenon. Set up the saw by trial and error until it is right before you cut the real pieces. The cam clamp holds the piece in the jig for a very safe and repeatable cut. To cut the shoulders, set up your blade height and use a block of wood on the fence for extension to leave more gap to clear the scrap (see photo next page). This way your saw will not jam. Use the miter gauge with a block of wood and a piece of sticky-back sandpaper so that your wood does not slide.

Plunge Router and Band Saw

A dovetail saw, filed for crosscutting, is used to make the shoulder cuts.
A dovetail saw, filed for crosscutting, is used to make the shoulder cuts.

To mortise with a plunge router, you have to make a jig like the one in the drawing at right, and in the photo on the next page. Mine holds a 3″ x 3″ piece so a table leg will fit into it. Smaller pieces get shimmed and wedged for safe work. Use a two-flute carbide up-spiral bit. On the router fence, I use a block of wood that slides back and forth in the jig safely. Take small cuts of about 1/4″ down each time. Cut halfway, flip and cut from the other side. I square up the corners with a chisel. If I am making doors, I round off the tenons and wedge them, as seen in the  photo at the bottom  left of the page. It’s much quicker.

To cut tenons on a band saw, set up the band saw fence and mark a scrap of wood, as shown at bottom right.  As with the table saw, cut it by trial and error and once the scrap is right, cut the real pieces. Cut the shoulders by hand with a dovetail saw.

Remember that all of these methods can be mixed. Use the one you like best.

I antiqued the stool by rounding off the corners unevenly with a chisel, rasp, broken brick, etc. I finished it with shellac and brown wax. From a cow hide, I cut 1″ strips for weaving the seat, which I learned from Brian Boggs’ DVD on hickory bark, sold by Lie-Nielsen Toolworks (lie-nielsen.com or 800-327-2520). PW

Click here to download the PDf for this article.

COMMENT