Shitage Kama (Stringer to Leg Joint)

After seeing a post a few months back on the Digital Woodworker blog on how to build Japanese sawhorses using only compression joints, I thought I would give it a try. The sawhorses are based on a design by Jay Van Arsdale, in the Jan-Feb 1990 issue of American Woodworker.

I had some Red Cedar lying around, which isn’t the best material for something that will be used quite heavily, but so it goes. Here are the basic pieces for 1/2 of one sawhorse: the stringer, the leg, and the foot/base-in that order.

The American Woodworker article does a fine job of laying out the measurements, etc., but what I was most interested in and what proved to be the most difficult aspect of the build was the Shitage Kama or “stringer to leg joint”.

(from American Woodworker Jan-Feb 1990)

I was able to visualize almost the entire joint except the angled cut on the leg that would accept the angled cut made on the stringer. So I just started marking and measuring in the hopes that once I got to that point, it would become clear. Here’s the layout on the stringer-pretty straight forward-one perpendicular saw cut and one angled cut.

1st cut:

Second cut:

Scrap material removed:

The next step was to layout and cut the mortise in the leg:

I used a brace with a 3/4″ bit to hollow out the majority of material, drilling from both sides to avoid tearout.

Next was chiseling out the remainder, carefully, again so as to avoid any tear-out, or at least as much as is possible when working with Red Cedar.

This part was the most challenging, initially in the visual sense, and then once I figured that out-in the actual chiseling of the angle. Essentially one has to carve out a 1/2″ angle in the leg mortise from front to back. To do this, I simply started chiseling out angled pieces in small increments in one direction from the above pencil line to the lower edge of the mortise on the back side. An extremely sharp blade works wonders here.

It may not look like much, but I was pretty happy for a first attempt. With the two wedges already cut (from Black Walnut) I was ready to insert the stringer and test the compression.

The lines aren’t perfect, but it works-I still have 3 more to do to build the pair of horses and improve my accuracy.

Both ends of each wedge are flattened. This allows for easy disassembly by tapping with a small hammer to push the wedges back out. You can also see a slight bit of the sawn angle on the stringer. I was a bit off in my measurements but it doesn’t seem to affect stability, although that will become more apparent in the finished sawhorse.

To build the sawhorses, I made an attempt to use only hand tools-where this fell short, at least for me was in removing the 1/2″ space in the base that delineates the feet of the horse. For this I used a dado set in the table saw. Red Cedar splinters so easily and for a long, thin strip like that, I went with the power tool. Otherwise, I’ve been using Japanese chisels and saws (ryoba & dozuki) and a low angle block plane for the angles on the base and leg. Once everything is cut and fit to size, I’m going to try using a new Japanese smoothing plane. That will be an entirely different experience.

I found a really basic, inexpensive ($47.00) one intended for beginners from Japan Woodworker.

I’m not finished with this project yet, but it’s been a really informative, enjoyable one. Getting the opportunity to work in the shop with only (mostly) hand tools (even though it is 95 F and humid, humid, humid) carries with it a certain calm and quiet. Just the sound of the plane on the wood, the shavings falling to the floor, the tapping of the wedges into place…those tasks carry with them a satisfaction that I’ve yet to find when working primarily with power tools. Maybe it’s the difference between working a tool and working with a tool.

Here’s a nice, short (10 sec.) video that shows the Shitage Kama rendered as an animation in Sketchup.

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