when you spend 8 days with Roy Underhill, stuff happens. One of my favorite moments from the joined stool class we had at the Woodwright’s School was when Roy reprised his demo of mortising under glass. Roy projected this with Frank Klauz at one of the Woodworking in America gigs a while back. I didn’t see it then, but asked Roy if he would mind if I boosted the idea for here. Mine’s photos, not video (I have enough to do without making my own videos) – so thanks Roy & Frank. what a great teaching tool.
a piece of plate glass clamped to the face of an oak board, then chop a mortise into the edge. Shoot thru the glass. This stock was air-dried riven oak. I need to try it on some green wood. but I grabbed what was nearby…
PETER FOLLANSBEE: JOINER’S NOTES 
This is great! The woodworkers ant farm in action.
Very cool to get a look at what goes on inside of a mortise. Something you don’t get to see often. Thanks for taking the time to take the pictures and post them.
Jamie
I am wondering about the method? most books say to not just dive into the center, but to remove the wood in “layers” ? this looks like it might be easier.
it’s fast & easy. About 4 minutes for a mortise 3 or 4″ long, 5/16″ wide.
If you remove layers I believe there is a greater risk of hurting the edges of the mortise. By starting in the middle you have a waste edge to pry against. Just my understanding of it though, haven’t chopped many mortises myself…
Brilliant Peter, so simple but how well it shows me what goes on when I am cutting the mortice and as mentioned the edge of the slit is protected and only cut vertical at the last opportunity………….
Thanks for posting this stop-action mortise. My take-away is how small/shallow the first few bites are. I’d read that, but now I know. (Or at least I’ll know it after I’ve done a few.)
Peter
Why not use a brace to open up what would arguably be 85% of the mortise, then clean it up with the chisel?
This is often done in timber framing as far as I know.
Drew
Drew: Why not? Because it’s wrong. Framing houses is one thing, the mortises are 1″ wide, 1 1/2″ wide or sometimes wider still. then it makes sense. Joinery work the mortises are usually 5/16″ wide. dinky. Big ones in joinery are 1/2″ wide & those are rare. Boring it first means you’re going over it twice. more chance for error. & slower besides. Chopping them up to 1/2″ wide, I just use the chisel. wider than that (bedsteads, for instance) I bore holes & attack it like a house-carpenter.