Empirical, not Imperial, is the measure of the pre-industrial maker.
by Jim Tolpin
August 2010, Issue #184
In this article I’m going to show how I design a simple piece of furniture whilst immersed in the mindset of the pre-industrial, hand-tool artisan. Because I’m not going to use power tools to build the piece, I can shelve my usual, machine-oriented design process to develop it. This means I won’t be bothering with drafting up (or SketchUp upping) numerically defined drawings in order to generate cutlists because, as you will see, I simply don’t need them. Machines need numbers – the hand-tool artisan doesn’t.
I start by roughing out concept sketches that satisfy the essential parameters of function and aesthetics that are the “givens” of the project. When I come to an iteration that looks good enough to pursue, I draw a full-scale rendering of it – and from there construct a cardboard mock-up that allows me to view the piece not only in three dimensions, but placed so I can look at it in the way it will be viewed in use. (Often, real-world views elongate or foreshorten planes and details in ways that are not obvious in drawing elevations.) Once satisfied with the mock-up, I commit the design to the traditional, analog recording system of tick sticks and templates. No tape measures or rulers of any kind are harmed in the creation of this design!
For Whom the Stool Toils
If I’m avoiding numbers, how am I going to derive and define the dimensions of this piece of furniture – in this case a simple step stool for my shop? Well, this is where it gets interesting.
Because this stool is to fit me in size and use, I can call on my body to provide all the primary dimensions. This is how it works: The human frame can be roughly proportioned in whole-number ratios of eight. We are eight of our hand-spans (with arms outstretched) wide and eight hand-spans high. Our head is one-eighth of our height. Our centerline to shoulder is one-eighth of our width, and our foot length comes out to be five-eighths of our shoulder span. (This latter relationship happens to make the step board come out to be close to the infamous, and inherently attractive, golden rectangle.) So in designing this step stool I develop its basic dimensions, as well as the location of structural intersections, around ratios of eight. Not just any eighths though: I use my own hand-span to provide the starting point information – after all, this stool toils for me!
The Particulars of the Parameters
The need here is to build a durable and stable, single-step stool for my own use in the shop – it will give me just enough lift to reach the top rack of my lumber storage and a few high shelves. To prevent slipping off the stool, I want some kind of textured surface on the step board. For aesthetic appeal I envision tapered angles and lines softened with curves. So here is the list of “givens” for this project:
■ Optimized in dimensions to properly fit my body
■ Stable no matter where I place my foot
■ Durable and strong enough to support my full weight
■ Non-slip step surface
Here’s how I intend to meet the givens: To provide stability, the step board should be about shoulder width in length (because the weight of our body, transferred through our feet, inherently falls under our shoulders.) To offer a safe and usable width, it should be a foot (that is, my foot!) wide. The height of the stool should be the rise of a comfortable step (again, my step). In the drawing below I show how I lay all this out precisely from the span of one of my hands.
For strength, most any hardwood is adequate to provide adequate bending resistance and to resist distortion in the joints. I avoid softwoods such as cedar and pine because side stress against their low-density grain would likely lead to loose joints and eventual catastrophic failure in the event someone jumped on the stool.
For long-lasting durability that depends on physics rather than chemistry, I’ll fasten the parts of the stool together with joinery that physically locks the boards to one another and does not rely on glue for strength. As you can see in the drawings, I’ll attach the stretcher to the end boards with through-wedged-tenons (which also provide aesthetic appeal), then attach this assembly to the step board with a pair of sliding dovetails reinforced against side movement with pocket screws. To provide a non-slip surface on the step, I’ll add some texture to the surface by hand carving a series of grooves across the face of the step board.
Drawing by Eye & by Golly
Operating in the pre-industrial artisan mindset I get to let myself go and draw on the right (I sometimes think the bright) side of my brain – the half that isn’t analytical and bound by a lot of rules and precedents. I grab a thick pencil (to forcibly keep myself from getting into the minutia of details) and rough out a perspective sketch that captures the basic functional requirements. I make a progression of sketches until I feel I’ve captured both the physical and aesthetic demands of the design. While I do strive for accurate perspective and pleasing proportions, I don’t worry too much at this point with producing these concept sketches in perfect scale. The next step, drawing out a rendering in three views, brings the concept closer to reality by pinning down the exact sizes and relationships of all the parts in full, true-to-life scale.
Once I have a concept sketch that I can live with, I lay out a piece of vellum (or other see-through paper) over 1″ square graph paper and prepare to draw the first full-scale view of the stool: the side elevation. (The graph paper eliminates the need for the cumbersome, slip-prone T-square.)
Now here comes the fun part: At the top of the paper I spread out my left hand and mark the extent of the span from the outside of the little finger to the outspread thumb. I then take the dividers and step out eight portions between these two points. I record this 1⁄8 hand-span by making a circle in a corner of the drawing; this trick gives me a way to quickly and accurately reset the divider.
Now note this: Every dimension and major structural intersection of this little piece of furniture will be based on so many eighths of my handbreadth! The result is three-fold: The stool will be easy to proportion using a set of dividers; it will fit my body perfectly; and, because the size of all its parts and portions relate in some whole-number ratio to one another, this piece of furniture is practically guaranteed to look pleasing and satisfying to the eye.
After drawing a base line I make a starting point then step out two handbreadths to establish the overall length of the stool. I draw out perpendicular lines to the base at this point by geometry or by simply eyeballing to the underlying graph paper. A safe and comfortable height of a step stool should be the rise of a natural step for the human frame, which is 1⁄8 of its height (which also conveniently happens to be a handbreadth).
So to mark the height, I simply step up one handbreadth on each perpendicular line with the dividers and connect the marks with my drawing stick. Because the drawing stick is a sample of the stock from which I’ll make the stool I can draw the exact thickness of the top by tracing on each side of the stick.
Next I draw in the end boards. The final concept sketch indicates that the ends are canted inward at the top – both for aesthetics and to increase stability and durability by triangulating the stresses that will be placed on the joints. I quickly see that I don’t want the ends to extend past the top step board (I don’t want to trip on them), but at the same time I want the base to be as wide as possible.
The obvious solution is to make the foot of the ends even with the ends of the step board. But how much should they cant in? Just by eyeballing I can see what’s too much and too little. What happens to be just right to my eye is, conveniently enough, two-eighths of my hand span. I step this distance in with a divider, then use my drawing stick to outline the side view (and exact thickness) of the end boards.
Now what about the stretcher? My concept sketch indicates that it should be located about halfway between the floor and the top of the bench. But how wide should it be and how far should it sit below the step board? Again, two-eighths of my hand-span seems to fit the bill in both cases. I also go ahead at this point and draw in the through-wedged tenon and add a nice little detail: a curve to the end of its tenon.
To create the end-view, I simply extend the base and height lines I established in the side view. Because I’m setting the width of the stool step to the length of my foot – which is about 1⁄6 the height of the human frame – I step out ten eighths of my handbreadth. (I’m rounding off one-sixth when I step off 10 out of the 64 eighths that make up my full height.)
To ascertain the cant-in of the end boards, I try going in two-eighths of a handbreadth as I did on the side view, but on the end view it looks too steep. Instead, I use the same ratio, but I make it relative to the width of the top. Now the cant-ins are one-eighth of the length and one-eighth of the width. To me, the cant-in now looks just right. I then try two-eighths of the width to set the width of the feet on either side of the arch and I step out one-eighth on the centerline to determine the apex (height) of the arc. That also looks good. I then draw the arc using a compass and straightedge to find its focal point.
However, because the end board is angled inward, its true length isn’t expressed in this face-on view – it’s foreshortened. To draw the end board to its true dimension so I can make a layout template, I need to “expand” the drawing to show the angles on the ends of the end boards. I also redraw the arc on the expanded view.
Make up a Mock-up
At this point, rather than going any deeper into detailing the full-scale rendering, I find it best to create a full-scale, three-dimensional mock-up of the piece so I can view it more true-to-life and from all angles. I transfer the overall dimensions from the full-scale rendering to the sheets of cardboard via a tick stick and a square. Note that I use the expanded view of the end boards rather than the elevation. After cutting out all the parts, I make slits for the “tenons” of the stretcher and then assemble the mock-up using brown packing tape.
Now that I have a 3D form to play with, I set it on the floor (where it will live most of its life), observe it carefully and start asking questions: Do the proportions look right? (They do.) Does the through-tenon show fully, or does the overhang of the step board partially hide it? (It does show OK.)
Would the step board look a little less severely rectilinear if I curved its ends a little? (Don’t know, let’s try it.) I add a strip of masking tape to quickly and effectively outline the curve without having to commit to cutting the cardboard.
As it turns out, the curve helps considerably, and I discover that the most graceful curve seems to be conveniently generated by making the curve a portion of a circle of which the focal point is at the centerline at the opposite end of the step board. I try the tape trick on the bottom of the stretcher but a curve there seems to be overkill and I overrule it. I’ll probably just make a chamfer of variable width along its bottom edge that just hints at a curve.
When I’m satisfied with the mock-up, I transfer any new information and design resolutions back to the full-scale rendering. I also finalize the location and cross sections of the joints, including choosing a width for the tenon of the stretcher that is “tool slaved” – that is, of the same width –
as one of my mortise chisels.
Let’s Make a Record
To lay out the components of this piece of furniture on the stock efficiently and with near-infallible accuracy, I create an analog – that is, a physical rather than a numerical – recording of the sizes of the components, the locations of their intersections, and the size and angles of the joints. On the story stick – which is simply a clean, straight piece of wood about 1⁄4″ thick by 2-1⁄2″ wide by a couple feet long – I mark and label the length and width of the step board and the stretcher. I also record the location and the angle of the cant of the stretcher tenon’s shoulder line. To record the exact size and details of the end boards, I make a template out of 1⁄8″ plywood “doorskin.”
At this point I won’t need the mock-up anymore and I can throw away the rendering if I wish. I also don’t have to worry about losing the cutlist because there isn’t one. All the information I need to make this project – now and forevermore – is fully recorded on one little stick and a small slab of plywood. Creating a design immersed in the mindset of the pre-industrial artisan, I revel in a place where I get to draw on the bright side of my brain where rulers no longer rule and I am free from the tyranny of numbers! PWM
❏ My hand (and foot!)
❏ Drawing surface and paper (vellum is ideal)
❏ 1″-square-gridded graph paper
❏ Straight-edged drawing stick (a straight-edge piece of stock trued to the thickness of the stock from which the stool will be made)
❏ Dividers – at least two plus a compass (a divider with pencil)
❏ Trammel points
❏ Bevel gauge (the thin, Japanese-type recommended)
❏ Pencil (standard #2 or mechanical with .07 lead) and white plastic eraser
For making a mockup:
❏ Cardboard sheeting (no folds if possible)
❏ Packing tape (brown) and masking tape (blue or green)
For transferring layout to stock:
❏ Story stick material (light-colored wood 1⁄4″ x 2-1⁄2″ x 24″)
❏ Stock for template (1⁄8″ plywood or thick Mylar)
Jim has been working wood for more than three decades and has written a dozen books on the subject, including “The New Traditional Woodworker.”