Lost Art Press

The French Triangle is Superior…

Posted on by Lost Art Press

French-triangle

…because it has six sides, instead of our puny three. No, no, I kid.

Let’s back up for a second for those who don’t know much about the “cabinetmaker’s triangle” shown above in plate 18 from A.J. Roubo’s “L’Art du Menuisier.” The triangle is scrawled on almost all assemblies so that we can immediately orient our pieces when we glue them together.

The triangle trumps all the crazy “AA, BB” and numbering systems I’ve seen and used. The triangle is simpler and almost foolproof.

So why is the French triangle better that a plain equilateral triangle? It is even more foolproof than a plain triangle. With a plain triangle that is marked on the edges of assemblies – think dovetailed drawer – there are times when a part of a triangle can look like the mark for a “true edge” – sometimes called the “carat.”

You cannot make that mistake if you use a French triangle. The loops at the base prevent it from looking like a carat. And the fourth line to the apex prevents it from looking like a carat at the tip.

Plus, chicks dig it.

I’ve been using the French triangle for about a month in my shop. When Megan Fitzpatrick, executive editor from Popular Woodworking Magazine, stopped by to drop off some lumber she saw the French triangle on a panel and said: “Oh, pretty!”

Reason enough. Now where are my Gauloises?

— Christopher Schwarz

69 thoughts on “The French Triangle is Superior…”

  2. Thanks. You’re not only informative, but you make it fun & funny, too! Now for a Gitanes…
    Tom H

  3. I like the fact that the fourth line bisects the center of the line that’s the bottom of the triangle.
    What’s the story behind the two strips of wood at each end with pegs thru them ?

    1. French edge-gluing clamps. No screws, just two wedges. Roy Underhill used this sort of clamp in early episodes of The Woodwright’s Shop.

  4. I must work on my sarcastic voice. I believe the connotation for which I was going was “twee” 😉

    I kid. It does help one see more quickly what goes where (but I’m not quite ready to give up my alphabet approach)

          1. Hi Chris,
            In Seattle we refer to someone in Fitz’s situation as being a Candidate. Short for PhC.

  7. I’ve long used the plain triangle to mark glue-ups and agree it is dead simple to use and near impossible to screw up with. I can see how the benefits of the prettier French triangle too and will have to give it a shot on my next glue up.
    I do confess to eschewing the traditional carat marking for true edges in favor of something more modern. I mark my true face and true edge of each board with a 🙂 Since I don’t remove my layout marks from the unseen underbits of my work I have left quite a few little smiley faces on my finished furniture and hope to add a little whimsy to the day of some future owner or historian when they uncover my unusual working marks 🙂

    Cheers,

    Josh

  8. I have tried several different methods for keeping boards aligned during planing, dry assembly and final glue-up. This looks promising I will give it a try.
    Thanks for your efforts

    1. “Who cares, just mark the wood and glue it together”, I think that would make a good book title.
      Or perhaps: “To make as crappily as possible”.

      1. Why do you insinuate that Joe is making something as crappy as he can, just because he is not overly impressed with the French triangle?

      2. Hi Jonas- I made no insinuations about Joe’s workmanship, I did however make a half-witty connection to the contrast between the title of Roubo’s “To make as Perfectly as possible” and the “who cares” comment above. The example above demonstrates novel method that eliminates the ambiguity of other marking conventions. These other marking conventions can cause confusion and generate error, making work crappier. Hens the hypothetical title: “To make as crappily as possible”. I hope I cleared that up.
        btw: at least about 60 care so far, to partially answer Joe’s question. Cheers.

  11. Triangle — Shmiangle . . . ! I was keenly interested in was the wooden clamp for edge-gluing. When I can, I prefer to make whatever appliances I can to assist my efforts in the shop, and this is certainly one that I will remember (and file, too). Yes, my daughters complain of their father inventing new words on the fly. Oh well . . . .

  13. “Alors, Francois, what is that scribble on those boards you have clamped up there?”
    “Ah, M. Roubo, that is the triangle of the cabinetmaker, n’est pas?”
    “It is?”
    “Oui.”
    “Oui,” said Jacques, passing by. “Of the cabinetmaker who has had one too many vin rouge. How many triangles do you see, Francois?”
    “Um. Er. Trois…?”
    Fin.

    1. now you know you should not be drinking in your workshop
      its hard to draw straight likes when you are drunk

  15. how about giving us a file for the picture above to take to staples to get a poster made
    is that possible?

      1. maybe the X marks the prettier side of the board in a previous step of working? but that would only make sense if there are different people working on it… choosing the side and drawing the triangle seem like things the same person should do…

  18. I wonder if the clamp would be “better” if the mortises that hold the moveable pin were slightly askew to better receive the wedge? It would not make construction anymore difficult but it may not make clamping anymore better.

  19. The clamps are neat. The fact that they are two sided so as to encapsulate the panel should help in preventing the panel from bowing in the center under the pressure of the clamps. Even my fancy-pants parallel clamps have done this to the panel that I am gluing up in my living room right now.

    1. are you familiar with the advanced machinery plano clamps
      they do the same thing but
      a little pricey

    2. Squeezeout may end up making the clamps a permanent part of the assembly. Nothing a little care and waxed paper wouldn’t take care of, but still something to keep in mind.

      2. A bit of finish on the clamp bars should eliminate problems with glue squeeze out. Some beeswax applied with a polissoir, perhaps?

  20. I wonder if the drawing might not show several steps in making a panel. An apprentice surfaces the boards, and marks the pretty/least wonky grain side, then a joiner joints the edges and fiddles along the edges until there is an acceptable fit and marks the triangle. Then they glue up the panel and the next day it is ready to do the finish surfacing. One thing is that on the couple of big panels like this I have done, after reading about it a bit, I have wanted to know which way the grain was running to finish plane the panel and minimize tearout, and so marked the good faces with an arrow.

  21. Those pins are obviously meant to be moved to work with panels of different widths, but I wonder if they are also wedged to accommodate different thicknesses of material, When joining panels you want pressure across the width to actually join them, but also across the thickness to keep them flat.

    1. JJ, I used a similar set-up I bodged up with some wood from an old pallet, glue and screws, when I was gluing up a table top at a friend’s place this summer. I covered the two rails on the face of the glue up with plastic wrap and then tapped little wedges between the back rail of the clamp and the back of the glued up boards to keep them as flat as possible across the face. Worked like a charm, better than the bar clamps I use at home mostly, though a little more fiddly. Lot cheaper too.

  22. Never mind the French Triangle… the wooden cramps are the real winner in the picture!
    However I reckon a pair of opposing wedges on the adjusting end would be better than one wedge between the moveable stop and the edge of the timber being glued as drawn.
    Why spend buckets of money on the metal versions with threaded tightening which are commercially available today at a ridiculous price when you can make you own? It’s enough to warm the heart of any anarchistic woodworker.

    1. I agree about the clamps. (Cheap bastard that I am.)

      Personally I think the triangle started it’s life as directions to a Paris bistro (or brothel) before being deligated to it’s current function. Seriously, look at an overhead view of Paris’ streets. That triangle is all over the place. Can’t you just picture two workers trying to figure where to meet after a long day of Roubo sending them out to get the proper dye ingredients?

  24. All very interesting, however, I was taught the cabinetmakers triangle a long time ago. It has served me well for all these years. So, in the American spirit, I will refer to the “pretty” triangle as the freedom triangle, in keeping with freedom fries, and freedom bread!

    Hope everyone has a great Christmas!

  25. Everyone knows or should know how good the french are at developing “triangles” They have been doing it for centuries

  26. How does one use this triangle thing to organize the dovetailing of a drawer? I mean, I’ve been marking the faces of the boards for which side is up by using inverted V’s, but with only 1/2″ or 1/4″ wide edges, there’s not much room to clearly mark something there.

    1. do you mean something like this? http://s14.postimage.org/gux1pib6p/triangle.png
      I think it tells you everything you need to know. you just have to decide in the beginning which side is up, and make sure that you can remove the markings in the end. but otherwise… I think even on 1/4″ edges you can scribble something like this… and that would make rather puny drawers.

      also… in my sketch I didn’t pay attention to anything but the triangle markings…. don’t judge…

    1. A caret is character shaped like an inverted “V”, or open-sided triange (Shift+6 on most keyboards). It is used as an accent mark in some languages, and also serves various purposes in proofreading, computer programming and technical notations. In traditional woodworking, it if frequently used to mark the jointed edge of a board.

      A carat is a unit of weight, used typically for gemstones.

      1. Ah, Gotcha see I knew karats were used to measure gold and such but I didn’t think that’s what he was implying.

  30. Years ago, when I was even more unskilled and impecunious than I am now, I lashed up a clamp system almost identical to that shown. I thought I was very clever, inventing something like that – which just goes to show that there’s nothing new under the sun, and the arrogance of youth. Tip – if you must try it, wax the clamp bars thoroughly to prevent the glue sticking to them. Works with PVA glue, anyway.

    It works, but has two disadvantages. You need about four hands to hold all the bits of workpiece and clamp in place before you get the wedge pressure on, and the pressure it can apply is quite limited. I gave up using them when I could afford a few sash cramps.

    I like the wiggly triangle, though. I’ll give that a try.

  31. I was going to give that book a pass until I saw this plate. That sold me (at least on the “cheap” edition).

    1. Thank you for that, Robert. It was beautiful. The kids especially were really getting it.

    1. The three sides are three lines. The fourth line splits the original triangle in half from the top point (apex) to the center of the bottom side.

      1. Technically those are all curves, since in euclidian geometry a line must be straight to be a line. We could use some flavor of curved space geometry to define curves as lines, but if we do that then pretty soon we would all be sitting around a closed box wondering if the cat inside was dead or alive, and how many cats there really are in the box, or if the box itself is even there. Then the French would be laughing at us while they invented the bikini. 😉

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