the Carpentry Way: Tréteau XXIII                                                          

Tréteau XXIII

You've arrived at the 23rd post as this build rolls onward. Previous posts in the series, along with other topics, are to be found in the 'Blog Archive' to the right of the page.

Just so everyone is not lost as to what part I am working on at this moment, today I will be showing the cut out for the short side braces at the opposite end of the sawhorse from the previous post - these braces I mean:

These braces are different than the ones I cut out in the previous post - notice how they attach, in the photo above, to the right-hand side leg. That leg is rotated to be aligned with the long plan axis, so the braces on the short side have overlapping slices, or barbes, to maintain a flat surface right across to the post arrises. That flat plane is important in such things as a roof surface, or large hopper, where planks would be fitted to the outside surface of the prism.

These barbes however, do not exactly simplify the cut out. I started with the most improbable looking one, which has a sliver of wood about 7" long on front. First I used my router to define as much of the tenon as I could:

Then I ran my circular saw in as far as I could to roughly define the barbe:

I followed up with a careful handsaw rip along the face of the barbe:

Then, as the French would say, "off with the head!":

Which left me with this:

I then started in on the chisel work to clean the barbe up:

The barb is really thin - less than 0.25" at its root end and tapering off to nothing, so I used the top of the sawhorse to support it while I shaved it down to the line:

The barbe is so thin and delicate that I have no option to use the kerfing technique to fit it, so I pare close to the line and hope for the best.

Next it was time to cut the 90˚ abutment at the bottom of the tenon using my azebiki:

When it was getting pretty close, I started checking it for fit:

It came out pretty well:

A view of the underside of the barbe as it fits against the leg:

I then went to work on the other three tenons - here's the trimming of the barbe on the upper side tenon for the same leg (DP):

And here I'm hacking away at the lower tenon on the opposite side, connecting to leg CM:

At last I could fit it all together:

This one will need a minor amount of trimming to get a tight fit all around, especially at the lower left connection, but it's close enough for the time-being.

Observation: those barbes are frankly a little absurd. In the case of the sawhorse, their position makes them vulnerable to damage - it would be easy to catch a pant leg on the corner and rip it or crack it. Even while I'm working on such parts I have to be very careful not to damage the thin edge and the point. As I can't in good conscience glue the barbe to the face of the leg, I will likely trim them back somewhat, to leave an exposed edge on the thing about 0.125" thick. Given the choice, it makes sense to me to design so as to eliminate the use of such contrivances.

I'm still a little puzzled why the French would choose to employ the barbe, when there are other options. It is useful to know how to make such connections, and it does relieve the carpenter of re-shaping the post, however if I were to make this sort of piece again, I would use the Japanese method of re-shaping the legs on all four faces so that no barbes would be needed and the joinery would be simpler to cut, with cleanly centered tenons, thus open to more possibilities in terms of the joints themselves, and would be more robust as well. Also, I think it makes sense to avoid, in the case of the sawhorse at least, bringing the braces to connect to the legs at the same height. If the heights were staggered, the short side braces could be done with through tenons, and could thus be wedged or pinned, or w.h.y..

I've been percolating through my head, as I toss and turn at night (like last night) a design for a new sort of joiner's or cabinetmaker's bench, one employing irregular splayed legs and the French bracing, and maybe a suspended tray underneath. It would be far stronger than the usual type with plumb legs and bolted stretchers, particularly in regards to resisting racking from the sideways loads imparted at times by planing and general pushing and pulling of objects attached to the bench top. I might start playing around with drawing this out soon. I have some ideas a cookin'!

I hope you enjoyed your visit to the Carpentry Way today. Comments/questions always welcome.

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