Saturday, August 11, 2012

CGSW Class: Mortise and Tenon

This morning I taught the fifth class at the Close Grain School of Woodworking, mortise and tenon joinery. My students were Reeve Goodenough and Colin Bourne.

Reeve chopping a mortise with a mortise chisel.

Colin chopping a mortise with a regular bench chisel.

Colin is one of my old Boy Scouts. Sadly, his father passed away in May from cancer, just four years older than me. I wanted to do something nice for him, so I thought he might enjoy joining us for some classes. I always thought he was the greatest kid, so I wasn't surprised when, a couple years after I had stepped down as Scoutmaster, I received an invitation to his Eagle ceremony. He awarded me his Mentor pin. Thank you, Colin!

His father was a US Army tank mechanic. Now Colin is following in his father's footsteps in the Army Reserve, something he's wanted to do as long I've known him since the age of 9. 

My best memory of him in Scouts is a winter backpacking trip two weeks after a huge snow and ice storm that damaged tens of thousands of trees in central Massachusetts. We were on snowshoes with backpacks and sledges, but the trail was so heavily obstructed by downed trees that we set up camp barely a mile in. I had previously shown the boys how to pile up snow, let it set, then tunnel it out for a shelter, slide a sleeping bag and pad in, and spend the night in it. So that's what Colin did. That's what I like about him, he's always willing to try things.

I started the class by going over a variety of tools for making mortises. This includes several styles of chisels for chopping them, and brace and bit for the quieter bore-and-pare method. Then I covered the saws for sawing out tenons, and the various tools for cleaning them up: chisels, shoulder plane, #10 bench rabbet plane, and router plane.

I went over the differences between through and blind mortises and the options for shoulders, pinning, and wedging. Finally, I went over ways it can go wrong, and how to clean it all up.

I demonstrated making a fully-shouldered through-mortise and tenon, showing three different methods for working the chisel while chopping. As usual, cleaning up and fitting the tenon took as much time as all the rest put together. Since they both liked the idea of wedged tenons, I ramped the mortise and sawed two slots down the tenon, then carved two wedges and drove them in. They also got the benefit of the pointers I picked up taking a class from Roy Underhill last week, where we made a mortise-and-tenon-framed door.

Colin sawing out a tenon cheek.

The guys hard at work.

Colin driving a wedge in.

Planing the joint down flush after trimming the slightly proud end of the tenon.

I love the fine shaving with the rectangular mortise hole in it! The shoulders were a bit rough, but considering that's Colin's first ever joint, it came out pretty well.

Reeve paring a cheek for a snug fit.

Testing. It fits!

Ramping the mortise prior to wedging.

Driving in a pair of wedges.

As always, I told them the thing to do is go home and practice this. It's probably better to start with looser tenons and practice making them more and more snug, rather than repeatedly spending lots of time tuning and fitting. That allows for faster repetition to get the skill down. You can also get a sound structural joint pretty quickly, even if it doesn't look the greatest. 

Reeve didn't waste any time. Later in the day he emailed me to tell me how excited he was to get the fit shown below on his third try. He said it was a testament to my class. Thanks, Reeve!

Reeve's third mortise and tenon joint. That looks pretty snug! He said he'll try harder wood for the wedges next time, since these squished down pretty flat. Photo by Reeve Goodenough.

The final class in the series will be dovetails. If you're interested in taking a class, you can sign up for one of the pre-scheduled group classes, or schedule a private class.


  1. Hi Steve, it makes me smile to see that the high tech generation is continuing the hand tool tradition. Thank you for your posts, I really enjoy them. I like your see one, do one, teach one phylosophy. I started working wood in 1960 and thanks to the computer generation, I am able to learn a great deal of knowledge from many sources. Thanks again.

    I would like to slip a P.S. to Colin.

    Hi Colin, I'm sorry that you had to say goodby to your father. I want to thank him for his service! I also want to thak you for your service in the US Army Reserves! I hope your career is successful, keep up the good work.

    Curtis L. Brannam
    Sgt. US Army 3 Oct 1967 thru 25 Nov 1973


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