Once the tenon is in the right rough shape, it’s time to start trimming so that it fits into the marked and well laid out mortise. A chisel can be used to shave the cheeks of the tenon, both smooth and square. This usually results in lots of thin shavings of wood that curl in on themselves — elegant little spirals of pine or oak or ash — as we try to build this bent before winter sets in.
The goal is to creep up on a tight fit, paring away material like a razor removes stubble or a cheese knife slices Parmesan: our objective is translucent shavings that gently nose in on the shape and depth of the tenon rather than looking to take out huge chunks that risk the tenon’s integrity.
Periodically we present the tenon to the mortise. It’s a little like foreplay, really — though it’s crass to say so — as the tenon’s size and shape gradually comes to match the opening of the mortise in depth and length and breadth. Don’t rush and don’t force the match here.
It must also be remembered that we’re looking to include as little twist in the boards as possible. The broad cheeks of the tenon must remain parallel to one another; as must the narrow cheeks. We’re not looking for higher shoulders, either. The tenon should be trimmed about 1/16” shorter than the mortise is deep; we don’t want the joint to bottom out and not seat home once there’s glue in the joint.
The goal is a right, tight fit — left, right, forward, back, up and down. The glue should be spread thinly rather than sloshed everywhere, and allowed to set. Remember that you shouldn’t glue a joint, though, until you’ve completed other necessary procedures — test fit everything, and mark your parts so that each mortise is matched with the right tenon.
I’ll be traveling for a few days, so this series will pause a few days, and only resume when I’m home and the weather is nice.
