the Carpentry Way: Tréteau XXVIII                                                          

Tréteau XXVIII

    
Post 28 in the build, approaching the end. Previous installments archived at the right of the page.

I'm still more than a bit puzzled as to the outcome at this point. The only thing I can conclude, that makes even the remotest sense, is that the drawing in the book is deliberately misleading - I presume the reason for that being the fear that the text, in the time in which it was originally published, would fall into the hands of a competitive carpentry school. And if that is what it is designed to do, then it fails in the end, as I have figured the method out, and now will be a lot savvier with working on any further examples from the Mazerolle book. I'm now expecting to be misled. And as for whether I will work on further examples from that book, it won't be for a while. I need to lick my wounds.

Now that I understand the method of layout presented in the text fairly well, I can stand back and ask if the sorts of things it facilitates are in fact the sort of things I need/want to know. I'm not so convinced about that point any longer. The adding of x-bracing, the Saint André's Cross to a splay-posted structure I am feeling is largely unnecessary. While it may indeed add a certain amount of rigidity, the splay-posted form is inherently quite stable as it is, and the added complexity of trying to get a multitude of angled pieces all to come together at the same time is a tremendous added difficulty and time burden.

In short, from a paying point of view, if I might be so crass, since the cross adds mostly cost, little apparent benefit, and the assembly itself would be concealed in the roof structure, why would any client want to opt for it? If it adds extra stiffness that is largely un-needed, at the expense of a lot more hassle, why would I want to do it as a carpenter, other than for amusement? Further, the x-braces, if they are to be incorporated into some single-layer hipped roof, leave one with much added work in terms of fitting jack and center-common rafters in and around them - again, a lot of added cost and hassle for negligible benefit. Finally, from a purist joiner's viewpoint, angled braces are always problematic anyhow because they function only in compression and any pegging is, at best, only of aid in assembly, because the angling of the brace results in a tenon with precious little relish beyond the peg. A moderate tension load will blow the relish out. It seems the French more often than not in this form of construction forgo the tenon anyhow and simply spike the braces in place, which is a dubious connection from my point of view. Even when they are using a tenon, it is invariably a bare tenon connection only, which is considerably weaker than a shouldered or housed tenon. Some drawbacks to be sure. Well, perhaps I'm just a bitter old man, mumbling and grumbling by this point and am missing out on some wonderful and important quality that the Saint André's Cross imparts to the roof structure, a quality that outweighs its many drawbacks, and if any reader would like to set me straight on this matter, I'm very open to hearing about it.

So those are some points I wanted to make now that I have reached this point in the process and the bubble has burst on me a bit as far as the overall methodology in the Mazerolle book. I am still grooving on the layout method though, and in fact in the workbench I am currently sketching, which will not have the angled braces in it but will instead be done in a Japanese style with nuki (penetrating ties), I am proceeding with the French layout method of using the footprints of the parts on plan as the main organizing and sizing factor. More on that in a later post possibly. For now, I will forge on to finish this sawhorse off so I can start using it.

The last step in the main frame are the interior x-braces. After a bit of wasting with the circular saw and some router work, I had defined one-half of each tenon, and for the rest it was saw time, and long rips were the order of the day:


Here I am experiencing a little separation anxiety:


Rough-out complete:


The upper end of the brace has a less-radically configured tenon and barbe:


Rough out done:


A while later I was sitting pretty with all the tenons on the interior braces ready for final trimming and fitting:


From the other side the lower end tenons can be seen more clearly:


So, in the book it shows these tenons passing right through the long-side braces, which I now realize is impossible, assembly-wise. The only way the braces, once lapped to one another, can pass through the long brace member is if they have an abutment on their upper end that is 90˚ to the axis of the long side brace. Just to show you how far away from that these are after rough cut out, I have laid a small metric square on to roughly show that 90˚line on the tenon:


Obviously, the tenon once cut would fall short of coming all the way through, thus I will not be doing through tenons. Here's the lower end, where the situation is even more extreme:


So, I will be trimming the tenon to a length of, oh, 1/2" or 3/4" in length or thereabouts and cutting some blind angled mortises in the long side braces. These tenons will either be left dry or possibly glued at time of final assembly.

That's what's on the slate for tomorrow - mortising and probably some fitting up. I hope you will return then to see how it comes out. Another couple of posts and this thread will be done, believe it or not. Your visit is always appreciated, and comments are most welcome.

--> Go to post XIX

Labels: