La Menuiserie Study (I)

Menuiserie is a term which translates into English as ‘joiner’s work’, an almost meaningless term in the US these days, or as (finish) carpentry, or cabinetmaking, and furniture making. Like finish carpentry compares to rough carpentry, menuiserie compares to charpente. In charpente there is some joinery, but a lot of the work is spiked together, and timbers are generally not backed to conform to a plane but are rotated to present one face to the plane and leave the other one out of plane. In menuiserie, the timbers are joined and are shaped to conform properly to the planes they meet or define, and in this respect menuiserie shares a commonality with Japanese carpentry.Yo say that menuiserie is simply cabinetmaking or carpentry is a little misleading in english, given the types of work suggested by those terms these days. Menuiserie overlaps a number of areas of woodwork and is probably best understood as joiner’s work – highly finished framed and joined structures, including furniture, built-ins, interior millwork, doors and windows.

One of the classic texts in menuiserie is L’Enseignement Professionel Du Menuisier, by Léon Jamin, dating from the mid-1800’s. Comprising 3 volumes, it remains on my wish list. What I do have as a reference on hand is a volume from an encyclopedia on the topic, put out by Les Compagnons Du Devoirs, entitled La Menuiserie. Volume 3 comprises a text book, of large format, and a separate folio of plates:

I’ve had this book for some time, and yet hadn’t made a dedicated study of the material. With a newborn, I now find myself at home a lot more, and with the occasional hour here and there to spend as I might like. So, when not trying to catch up on sleep I have delved in to this modern text, starting at page 1 and drawing every exercise in the order they are presented.  La Menuiserie presents a fairly systematic path through the material, beginning with basic geometry exercises like drawing parallel lines, drawing perpendicular lines, triangles, angles, polygons, etc. Thought that material fas already familiar to me, I drew the examples, using SketchUp instead of paper, compass, etc.

From the most basic stuff, La Menuiserie moves into drawings of ovals and various curves, then to ellipses, including a cool method that I had also noticed previously in my Mazerolle text but had never explored:

It’s a very easy-to-remember and accurate method to produce ellipses, and if anyone is interested I’d be happy to show how to do it step by step.

After ellipses the study moves to curves developed on slopes, like this one for example:

An application for this sort of thing would be laying out a domed roof underneath a pent roof – as the following example on the right shows:

Next the text deals with drawing the line of the ‘policeman’s hat’ (chapeaux de gendarme) – here are two methods:

Next, the volume deals with spirals of various types:

Archimedean spiral on top, two-point spiral below.

Spirals on three points, four points, and six:

And extension on the theme of spirals are volutes. Here are four different types:

All of the above exercises are merely a preamble to the sections to come. The first part of the more involved study is titled Éléments de géométrie dans l’espace. In that chapter the exploration commences with a consideration of the basics of descriptive geometry,  orthogonal planes and the forms of the basic solids like prisms, cylinders, cones, pyramids, and so forth. At this juncture, the supplemental box of plates still hasn’t been cracked yet.

There are a series of exercises to develop the surfaces of cones, and then truncated cones. 
Here’s the development of a right cone with sloped truncation:

And this is the development of an oblique cone with sloped truncation:

Notice the characteristic shapes of the developed surfaces in the above two examples? With a right cone, an oblique cut of the cone produces a developed surface which has a horseshoe-shaped cut. With an oblique (or scalene) cone similarly cut, the developed surface has an ’M’-shaped cut line.

Now, as I worked my way through the above two exercises, there would be times when I would refer to the text, which of course is in French. At least it is not 19th century French like the Mazerolle book, but it still exercises me a bit to translate. I did, after all, flunk out of French 11 in high school. At one point I decided to look on the web to see what else I might find on the same topic of developing conical surfaces -perhaps there were other methods worth looking at – and I came across a French Wikibooks page on the topic, titled Traçage en chaudronnerie et tuyauterie, which I translate as ‘Templates for Boiler and Pipe Work’. Developing surfaces like cones and cylinders is a standard sort of thing for fabrication of pipes and ducts.

Here’s what that page showed for the development of a right cone with an oblique truncation:

The developed surface shown was contradicting the La Menuiserie text I had, with an ’M’-shaped development from a right cone instead of the horseshoe-shaped development. Hmmm….

Well, only one of these developments could be correct (or neither). In SketchUp there is no convenient tool with which to unfold curved surfaces flat, so I drew a scalene polygonal cone and unfolded it (which was a tedious task) to see what shape was produced:

There we have it: the ’M’-shaped cut line associates to the scalene cone, as my text showed. That French Wikibook page was incorrect. I went into the history for that web page, and note it has been up for 6 years, the diagrams edited for clarity at different times, and it has been wrong on that development the whole time. Funny how things go like that. I hope it hasn’t confused too many boilermakers or pipe-fitters in the interim. Someone must have mixed up parts of two sketches.
I’ll continue this account in some further posts. A series begins. Thanks for visiting the Carpentry Way.

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