Sunday, January 31, 2010

Tréteau XIV

Back to the Mazerolle tréteau, or, welcome to my nightmare. This sawhorse serves as a vehicle for roof carpentry study, and I do need more than one sawhorse, so what the heck! Previous installments are found in the 'Blog Archive' to the right of the page.

One thing I'm thinking of doing a little differently from now on with these longer threads is to reference what I am doing in each thread to the project as a whole. I can imagine with lots of parts and some similar regimes of cut-out, it can sometimes be a little confusing for the reader trying to ascertain exactly what I am up to at a given stage.

Today I'm going to show the cut out work on the long side x-braces, or the les croix de Saint André, indicated in red in the following picture:


The Saint André crosses, by the way, would be translated as 'Saint Andrew's crosses' in English, though actually in English they are called 'saltire' braces. Funny enough, there's no getting away from the French language here with the term, as the origin of the word 'saltire' is old French saultoir/sautoir, which in turn comes from the Late Latin saltātōrium, meaning 'stirrup' and ultimately from Latin saltāre, which means 'to leap'.

The first order of business was to process these two lap joints, which are mitered half-laps, with the miter unequal on each side of the brace member. So, first I laid out the two miter angles on a stick of red oak, then hand-sawed to the line and planed them true. Here we are part way through that process:


After the surface is decked flat, I check with the bevel gauge and adjust as necessary until the bevel is where I want it:


Then the block is clamped in position and the chopping commences:


After all sides are pared, this is how things look:


Time for a little togetherness:


One side ended up with a slight gap at one miter, unexpectedly:



Here's the backside of the same crossing:


Notice the small chip-out at the upper intersection. Fortunately, I didn't lose the little piece and was able to epoxy it back on later.

Now it was time for the fiendish part - the angled tapered mortises. I wasn't expecting it to be such a good time, though it was really just a matter of patience.

The mortises slope two directions and taper, and while my first thought was to run screaming, in the end I decided to fix the stick atop my sawhorse with a couple of pieces of mdf acting as shims to incline the piece, so as to relieve me of having to angle in two awkward directions with the drill:


Clamped down, I was ready to drill, which was a combination of eye-balling and prayer:


Typically, this was the point where the drilling left off...


...and the chopping could begin:


I have eight of these nasties to cut out - here's one:


And I'll take the other ones up next time, as I've reached my self-imposed 15-picture posting limit. Hope to see you next time. Thanks for dropping by. --> Go to post XV

4 comments:

  1. Impressive as always. I was asking myself if I needed a marking knife. Seeing your results I can still go a long way with a pencil.

    Verifying saltire on wikipedia, I see that the term "Saint Andrew's Cross" is also known in English heraldry (the Scotisch flag).

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  2. Realy impresive joinery! do you do every thing with hand tools? This will be a sturdy saw horse!!

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  3. Hi Damien,

    As marking knives, I tend to stick with pencil lines when the mortise walls are at oblique angles to the face of the material as it is difficult to knife in alignment to the mortise. I guess I'm a little inconsistent as well with a marking knife - I tend to use them in softwoods more, and more usually in the straightforward rectilinear work and for tenons more so than for mortises. I do like marking knives and feel that a single bevel, single sided knife is best. Still I know several skilled carpenters who eschew the use of a marking knife. You might want to give it a try - it's not a particularly expensive tool (with exceptions).

    When time comes to work on the tenons, I'll be using my marking knife in this build.

    ~Chris

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  4. Hi David,

    thanks for the compliment. It's not that I do everything with hand tools - it's that I'm working in the kitchen and I try to limit the dust. My wife will get aggro otherwise. I like all sorts of tools, and like be as versatile as I can with various types of equipment, drawing the line at the CNC-operated equipment. I think there are skills of various kinds, both in guiding a tool by hand and in setting up a power tool to do accurate work. It is good, I think, to be able to use hand tools effectively, because of their portability, directness of use, and the inherent intimacy with the material that they bring, but if I need to slice a log up into boards, I won't be opting for a pit saw, if you know what I mean.

    And yeah, as you note, this will be a sturdy sawhorse, probably capable of withstanding a direct nuclear attack, or at least parking a car on top of it. I hope to have it's use for many years, and I've already learned so much from tackling the project.


    ~Chris

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