Cheap Seats: Form of a Forme

Detail of the Werl Alterpiece, Flemish, painted by Robert Campin 1438

Of four alterpieces painted by Campin that depict settelbancs, this one is where we will be drawing the primary inspiration for the form of the sides. Also, of the four paintings by Campin, this is the only banc where the backrest is affixed to the outside of the “arms” and is also octagonal in shape. While these aren’t necessarily going to be features of our “Cheap Seats” projects, they are interesting ideas to bear in mind to personalize any later reproductions.

The greatest asset in this type of settelbanc, for our purposes, is the lightness of form. The large areas of “empty” space between elements means that a great reduction in weight can be achieved over a fully paneled style.

Side Sketch

A view of the side as designed.

Front Sketch

“Front” view. Since the rotating backrest makes the chair ‘reversible’ the “front” and “back” are identical.

So that brings us to the sketch. The design is laid out in module form, having no specific measurements in the design. The width is 1M, depth is 1M, and overall height is 2M. The seat is set at 1M from the floor. Some time ago the folks at St. Thomas Guild did a blog post measuring several extant settelbancs and translating the measurements to rough proportions. Those proportions give us the basis for deriving the placement of both major and minor elements. In this case, 1/4 M for the area covered by the detail elements below the upper and 1/3m for the lower rail. For a wholly “proportional” description, those elements are 1:3 and 1:2, in harmonic expansion.

Where are we getting the “M” from? Turns out a comfortable seat height for a given person will be about twice the span of their hand. This makes 1M=twice the length of your hand, from heel of the palm to the middle fingertip. If you are making this for yourself, this is your measurement standard. For someone else, measure their hand. I’ve found it useful to mark the length of my hand once and use that as the standard “rule” for figuring everything after. The actual distance is transferred to the wood by means of a set of dividers. Another option would be to cut a stick to that exact length, or make a rule that permanently records the distance of one hand span and multiples of that span. Perhaps I’ll show how to make one of these as a Thursday Extra later on in the project.

Getting back to the sketch, there are some dotted lines that indicate the estimated location for hidden joinery that will allow the seats to be removed from the sides, making these settels pack “flat.” The rails are estimated to be 1/6th the width of 1M, following Medieval Design conventions. I realized after the fact that this makes the sides of the chair look very tall and narrow. To adjust, we’re going to do something that artisan designers have done nearly consistently with every piece ever produced — we’re going to exclude the thickness of the legs/stiles. This means the stiles and top rail will frame the space of the sides, which will remain 2:1 height to base. The middle rail will still divide the sides at 1:1, and we’ll gain a little more room to lay in any decorative elements, like the broken foils suggested in the lower half of the sketch. The central stile will stay 1/6M, which should still match the width of the visible face from the sides, and provide an even division of the upper section. This also provides functional support of the “pin” that will hold the swing arms for the backrest.

The proportional width of the chair will likewise stay completely between the thicknesses of the sides. That means we will have two hand spans across the width. If you’re concerned about his being too narrow a seat, add another hands-breadth to the width. A hand’s breadth is a half of a hand span, and therefore pretty easy to find the “measurement” with a set of dividers and 7th Grade geometry. For something more elegant, translating 2 hand spans into parts of 3, then adding a fourth part of three will generate a little more width while keeping more in line with Boethian proportioning (seat width is now 4:3 of 1M).

I’ve also generally left off any adornment. These can be determined later or left off completely. A little additional work, however, will go a long way into making this look like a much nicer piece of furniture.

It’s about time to cut wood. I really need to find one decent pallet to use for this project at this point. Better check Craigslist.

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This entry was posted in Cheap Seats, Design and Proportion, Furniture Research, Projects. Bookmark the permalink.

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