I’m going to do a half lap with a cross cut, chisel paring, and followed through with a shoulder plane. Now if you didn’t know better, you might be thinking I’m an Olympic diver getting ready to execute a stunning high dive. But alas, I am not. I’m a woodworker, and this is a structural joint and the tools I will use to make a simple, yet strong woodworking joint.
The Half Lap is a joint used to connect two intersecting pieces of wood. Each piece of wood is sawn to half its thickness. When the two are then overlapped, the two are now again the thickness of one.
In times of old, this might have been considered as an inadequate means of joining two boards together. In early time glue was not available. I imagine to secure this joint, the boards would have had to be drilled through and fastened by dowel rods. Or maybe they nailed it? Either way, it would not have been a good joint to hold up against any rugged usage.
However, with today’s modern glue, it has the ability to adhere to the wood with incredible strength. If you would try to break it, the wood would snap before the glued joint would fail. Wood has three edges in which glue can be applied. Face grain, the large, flat surface area of a board. Edge grain, the smaller side of the board running length wise. And end grain, the ends of the board, running width wise. Yet, end grain gluing is an inadequate means of bonding two pieces together.
I’m going to begin with making my boards. I’ll have one horizontal on my bench and the other standing vertical. With a sharp pencil I’ll mark the vertical piece on the face and sides using the horizontal piece as a gauge. Then i’ll reverse the two pieces and mark the same on the other board.
Using a marking gauge, I’ll set it for half the thickness and run it down the sides of the boards.
With a square and a sharp knife, I’ll scribe a line across the face of the board following my pencil line. I continue to make a few passes with my knife. Then I angle the knife, removing a small amount of wood, creating a shoulder or trench on the waste side for my saw to rest in. I’m going to do this for both pieces.
I’ve picked up my crosscut saw and using that trench as a guide, I’ll saw down to my marking gauge line. I’ll move my saw over 3/16” and make a series of saw cuts repeating this until I come to the edge of the boards.
Now comes the fun part. I use a ⅞” chisel and place it in between the saw kerfs. Pry the chisel and most of the wood will snap out. I love doing this. It’s fast, easy and there is something fun about it. Maybe it’s the sound of the wood breaking like the sound of knuckles cracking on fingers. I’m not sure, I just know I enjoy doing it.
The mating surfaces are still rough at this point. So I’ll smooth them out with a shinto rasp. I’ll do a test fit to see how the joint fits. If the half lap isn’t quite wide enough, I’ll use a shoulder plane to carefully shave the joint so the fitting is exact.
From there it’s just applying the glue. I’m going to spread the glue evenly on both mating surfaces. I want to make sure that I’m using all the surface available to me to get the maximum holding power. Then I apply the clamps and let it set overnight.
If you would like to see an example of this joint being made, check out my videos at
www.youtube.com/bigchopperoo and watch “Craftsman Frame- part 1”
Chad Stanton- Stanton Fine Furniture
-- Chad Stanton, Big Chopperoo www.woodchoppintime.com