I hate three-legged chairs, especially those with a full seat and back, and one leg under the back. They always look ridiculous when viewed from behind and make dangerous contraptions to sit in . If the person seated in such a chair leans slightly sideways against the back, the chair will tip over. The person might get hurt, and you might get sued if you are the designer and maker of the chair.
Many students and designers mistakenly decide to make a three-legged chair just to be different . They must then con struct around the design . This usually results in some awful kind of hodge-podge. There are well-designed chairs that are a result of their function or space allowance dictating three legs instead of four. For example in some valet chairs, the rear leg and back are designed primarily to support clothes hanging on top. The requirements of such chairs do not in clude the comforts of long-term sitting and leaning, as would a lounge or dining chair.
Three-legged chairs might also be made for a round dining table where the designer wants to fit as many seats as possible. The natural solution is to make the chairs pie-shaped ,. with the one leg in front . This is fine, because the person 's two legs will help support the front, and the chair will be very stable. There are sculptural three-legged chairs made of wood or metal that are so heavy it is impossible to tip them, but this of course doesn't mean they are well designed.
The designer of a seating unit should fust decide precisely what function the chair or stool is to have. Then he should choose his construction technique and design around the construction. The result is usually a well-designed and functional seat. Of course the designer must have a feeling for form and dimension . The forms must be consistent so that the piece ties together and doesn 't look like one base with a different top placed on it . I found proportion-the right re lationship in thickness, width and sizes-the most difficult thing to learn. Most of my students have the same problem. A poorly proportioned chair can spoil an excellent design.
When I started designing my seat, I did not have in mind at all that I wanted to make a three-legged stool . But as the design progressed, I did not have any choice. I wanted a stool with a back, and a system where I could use the same seat in three different heights by changing the length of the legs. I wanted the stool to be comfortable, but of minimum size-as light but as strong as possible . The middle-size stool is more like a small chair, but I will refer to them all as stools in this article.
Here is how the whole thing started : My wife and I went to a horse show. We were sitting on a six-inch wide rail for sev eral hours, yet we felt quite comfortable. Of course I am well
upholstered , but my wife is just right. And she didn't complain ei·ther. All of a sudden I realized that when you sit on a straight wooden seat, you sit only on your two cheek bones . The rest of the seat is unnecessary. Of course, a full wooden seat allows a little freedom for moving around , unless it is carved to hold you in position .
I began experimenting to find the smallest comfortable seat I could get away with . I came up with a piece 6 in. wide and 16 in. long, with a 7 / 8-in. curve. This piece is very pleas ant to sit on , and I could bandsaw it out of an 8/4 plank.
I wanted a back, but I wanted a minimum of wood for the seat, so I mortised and tenoned a small section to the back of the seat. This piece connects to the backrest with a through dovetail. (In production , finger joints could be used .) Now, because the piece behind the seat was small, there was only room for one leg in the back. This meant the backrest had to be narrow and low, which was fine as I only wanted to support the lower part of the spine.
The tee-shaped seat counteracts the tendency for the stool to tip over, because there is no seat area in the back to push against. The weight of the body locates on top of the two front legs. I ended up with a stable three-legged stool, with the third leg in the back. Of course, with a little extra effort this stool can be toppled more easily than a four-legged chair. As mentioned, I wanted the chair to be comfortable and strong yet as light as possible. I needed width at the top of the backrest for support, but not at the bottom . So I removed the excess and curved the two outside lines, which resulted in a pleasant oval-type shape. At the same time, I needed the full wood thickness at the backrest bottom for a strong joint, but not at the top . I removed the excess, but in a straight line, because in the side view all tapers are straight lines. If a curved line had been used it would have looked bulky , since there was not much thickness to play with . I also replaced the corners of the seat with a rounded line which gave me more of an oval . I needed the thickness of the seat at the center for the mortise and tenon, but not at the ends, so I removed the excess there also, which added another curved line. Now from the front and top view everything was oval . I continued this form in the handle for moving the stool . I curved the ends of the seat and backrest, and eased the corners so that all the lines would flow together smoothly. I eased off the front edge of the seat for comfort, but gradually brought the line crisply around the top of the back. This type of detail gives a piece a little more of a handmade feeling. A hand router that removed the same radius all around would have given the piece a machine-made look.
To avoid errors, Frid superimposes front, side and top elevations into one full-size drawing. In the shop, each view would be in a different
the stool more stability. The ends were turned down to 3/4 in. and joined thtough to the top of the seat . (When wedging legs through a solid top, always place the wedge so it goes across the grain of the top to prevent splitting.) The stretcher was a simple tee, joined through the legs and wedged.
I made my prototype after making simple preliminary drawings. I always make a mock-up when I make a new chair or other seating uriit to test the comfort and to see how the shapes relate in three dimensions . I assem ble the prototype the easiest way possible, usually with nails. I make it out of the cheapest materials I can and don 't bother to sand it .
In this case, I made my mock-up stool exactly like my pre liminary drawings, and found it very comfortable, but it looked awful . I could not put my finger on what was wrong, Seat heights shown here are about 12 in . , 16 in . and 21 in.
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color. Dimensions shown above are for middle-sized stool; detail at top right shows seat and back joinery.
so I set the stool aside in my shop in a place where I could not miss it when I came in . During the next few weeks several people came in and sat on it and found it very comfortable , but no one was crazy about its looks. One day I was sitting and staring at it, and I suddenly realized what was wrong. Everything on the stool was oval except for the legs and stretchers which were turned round . The piece looked like a base from one chair with a top from another. I cut off the legs and made the legs and stretchers oval , and then the stool looked like one unit . Testing the prototype a little further, I discovered that if ! moved the backrest one inch back, I could sit on the stool just as comfortably backwards. I didn 't start designing with the notion of making a three-legged stool, but the shape resulted naturally from the construction and from the requirements I originally assigned to the design .
Then I was ready to make the final working drawings for the stool . It is impossible to make a chair or stool without a full-scale working drawing from which to take all angles and measurements. The drawing must have a side, top and front view. (In some chairs, a back view is also necessary .) I. always superimpose the three views, using a different color for each view. Having all three views on one drawing takes up less space in the shop . But more important is that by superim posing the three views, it is harder to make mistakes . If a small mistake is made in a dimension on one view, it will be transferred to the other two, and easily noticed . This ensures that the chair will go together. With three separate drawings it is much easier to make an error because dimensions have to be transferred from view to view by measuring. But when the three views are on the same drawing, all the lines can be pro jected from one view to another.
Three-view drawings might seem a little confusing at first , but after a short time you get used to reading them . It is possible to transfer the lines onto three separate drawings by projecting them, but this requires a big drawing table . I still prefer to make one drawing with all three views, and if later I want separate drawings I can trace them from the three-view drawing with less chance for error.