Saturday, November 14, 2009

Tréteau V

The odyssey continues. I've been drawing and drawing and drawing - in between other paid drawing work I am engaged in for a client at the moment - and when I take a break from the drawing, well, I can do some layout on the wood, which is in fact simply more drawing. I'm going batty!

This sawhorse is a fairly complex piece. As of today I have completed the 2D drawing details for, and subsequent layout of, the main top beam, and the four long side braces. I keep thinking about trying to find a way to explain the layout to the readers here, but it is the case I'm afraid that due to the complexity level I would have to spend a LOT of time trying to describe mere isolated aspects of the layout. It seems like a tough thing to explain with clarity unless I write for what might be months. Maybe once I have a better grasp of the subject, after making this piece and letting the material soak into my skull a bit more, I will hopefully find a good way to go about explaining some of the layout stuff.

I'm finding that doing the complete drawing, which I have now done at least 15 times (to one extent or another), takes about 25~30 hours per round. And the layout on the wood hardly proceeds with any great alacrity since one has to be fairly circumspect about it - it's so easy to place the lines in the wrong places. I've done plenty of erasing already - by which I mean scraping, as a card scraper is the means by which I am removing erroneous marks.

The mechanical pencil, my usual choice for layout out on wood, has a lead which is unfortunately of a colour -gray - that blends in with the Canarywood all too easily, so I have switched to a Staedtler 0.35mm black ink marking pen, which does a good job but seems a bit fragile at the tip.

Here's a few pictures of the completed laid out pieces, in no particular order...

The piece to the left shows the inside face where the upper end of the interior x-brace mortise is located, and the piece on the right shows the brace's lower tenon, this one going through a leg which is turned 45˚ to the plan:


Here's a view of the tenon layout at the top end of one of the braces:


The cut-out will definitely be challenging, if not downright diabolical, in a few spots due to the long slopes across faces and tight interior intersections of planes in several spots.

Here's some of the mortises laid out in the upper surface of the beam:


And a view of the mortises emerging at the underside of the beam:


Same view of the underside of the beam, this time of the mortises for the long braces:


And another look at mortises for the legs on the underside of the beam:


The drawing work has been a challenge to figure out, to say the least, partly because of the errors that I find in the original (if it is original and not a copy), and partly because a fair number of development lines are simply omitted from the drawing. To give one example of that, take a look at part of the original drawing which concerns the spot where one of the long braces slopes down to meet a leg:


That doesn't look too bad at all, until one actually goes to work on the development of the brace - in particular the brace which meets a leg turned 45˚ to the plan. Once that scratching is completed, the view is a tad more congested:


It occurred to me that a nice application for this form of sawhorse wold be to make a joiner's workbench. Unlike a table, say, a person doesn't need to pull a chair to sit at a joiner's bench, so the crossing braces wouldn't interfere with anything. Since having a shelf in the lower section of the bench generally just results in, uh, dust collection, it would be fine with just the structural elements. Of course, one could always sling a few drawers in under the top if need be. It would be great to have this sort of structure for a planing bench, as it would be absolutely resistant to back-and-forth loads, much more so than the usual non-splayed trestle-based bench. I'm keeping that in mind for the future, and for now I'm keen to see how this sawhorse turns out. With such a hard wood and all the awkward joints and multiplicity of interconnection between pieces, it seems like it will be a miracle if everything fits just right when assembled. We'll see of course.

Anyway, I'm rolling onward. Next step is to develop the views for the short side braces, then the interior x-braces, and finally the legs. Then lay it all out. I'm guessing, given my schedule at the moment and the somewhat reduced available time I have to devote to this, it will take about a week more to get to the point where the layout is all complete and I can start hacking into the wood.

Thanks for visiting today. --> Go to part VI

2 comments:

  1. One of the reasons for the 'errors' in the drawings of Mazerolle's book could be the fact that it is hard to erase or repair mistakes made on the etched medium, especially when the drawing is complex it becomes basically impossible.
    As you mentioned it is hard to draw all the lines correctly from the first try. Maybe mistakes where made in the drawing process and consciously left, since trying to repair them would make things probably worse. And as you know this drawings are very time consuming even more so when drawn in this technique, so leaving them was maybe a conscious decision?
    It is just a guess since I have experience with this medium not with those particular drawings.

    As always I am looking forward to your next post. I wondered if you found time lately to make any progress on the comprehensive articles for the hopper and first sawhorse you have been working on? I imagine you have been busy with more important things. But I still look forward to those as well.

    Mathieu

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  2. Mathieu,

    thanks for the comment. That's a reasonable theory as to the source of text errors - I hadn't thought about the role of a person who originally engraved the printing plates. That would definitely explain it. The original drawing would probably have had so many lines, some of which would have to be left out, and if he engraver was not immersed in the drawing methods himself, it would be all too easy to make various small mistakes in copying the text from the source material. Your idea makes good sense Mathieu - I'll buy!

    As for the comprehensive articles on hopper and sawhorse, I am a little behind on that with the recent consultation work that occupies me, but the material is all put together and I am halfway through the editing process. The computer switchover earlier this month also slowed things down a bit too. I originally thought I'd be ready by this point in the month, but I'm afraid it will be more likely the end of this month (November). It will be done soon, don't worry!

    ~Chris

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