Ian Kirby Woodworking Design: Understanding Furniture Layout Proportions

Ian Kirby Proportion Lesson This bookcase was created with shelves of different proportions to hold different sized books, something important to consider when it was initially designed. Furniture can be made of many different materials. All furniture, wooden included, can be divided into two broad groups, generally referred to as case goods and stick furniture. Case goods are those things which have doors and drawers — storage furniture. Stick furniture is tables and chairs. The difference between them visually is that case goods present us with a solid cuboid object. Tables and chairs are made up of legs and rails that have spaces between them. It is a difference that brings considerable complexities, each of its own kind. [caption id="attachment_5727" align="aligncenter" width="300"]Bookcase Plans The plans for the bookcase started with laying out the front and side elevations, ensuring the proper proportions is the first step toward starting your project. To help put this admittedly difficult topic of design into a practical context, the piece I’m going to use as an example is a wallhung open bookcase. It falls nicely between the cracks of these two broad groups because it’s not a closed box, but neither has it any parts that enclose an open space. This piece also raises a difference between the projects that you make as a furniture maker and bought furniture. Your work, in all but rare instances, is site specific, which means that it is composed and made for a room or a particular place in a room where it will live. It is often subject specific as well, meaning that you are making a piece not only for a specific location but also a specific use in that location. So it is with this bookcase. It’s both site and subject specific since it is adjacent to the kitchen and intended for cookbooks of mostly large and medium size.
The Primary Consideration
Regardless of all other visual considerations, one is paramount — a first principle of furniture design, if you will. And that is proportion. It is the single most important aspect of any piece of furniture to which you should pay attention. To parody the mantra of real estate agents, furniture is about proportion, proportion, proportion. That doesn’t mean there is anything absolute about proportion. What it does mean is that every set of major dimensions, as well as every detail, has to be considered in the context of proportion. You may well ask, “explain proportion.” The easy and countable explanation is that it is a quantity of something that is part of a whole amount or number. Less simple is the uncountable explanation that it is the relation of one part to another or the whole with respect to magnitude or degree. Unfortunately, understanding that sentence does not bring with it the ability to judge proportion. What I’m going to do, therefore, is go over this project in some detail regarding its various proportions in the hope that it will help guide you in your own efforts.
Examining the Piece
Looking for the first time at a piece of furniture should be an act of discovery. From a distance, the piece makes statements of its parts and their proportion. Viewing it from the middle ground reveals more prominent details and, close up, we find the minute details. The front elevation of the bookcase has five parts to it: three spaces which have backs to them (for books) and the spaces top and bottom which show the wall. By the nature of the case, the spaces are all the same width. The top and bottom spaces are equal in height. The shelf spaces reduce from 12 to 10 to 9 inches as they go up. At first glance, this elongates the effect as well as offering a more comfortable look than equal spaces — which would firmly announce a strict regimen with no concession to the subtle though comfortable diminishing dimensions. The shelf spacing is emphasized by two details that you see from both the front and the side. The first detail is the projection of the shelf beyond the edge of the case, and the second is the line of through joints. Each plays its part differently, yet they are clearly combined. It is in the middle ground of this piece that you notice that the shelves project in two ways. They come forward off the sides and overlap the edge of the sides. As well, they have a rabbet on their projecting edges and ends. Each dimension of these details should be considered as a proportion judgment. The net effect of the rabbets is to give a more slender look to the shelf thickness. It does one other thing. The rabbet is a molding. All moldings, simple or complex, have the effect of creating highlights and shadows. That’s what they do, and that’s why we use them. When you look at a molding, you may not be able to immediately visualize its section, but you will see its effect in the highlights and shadows it makes. Such is the case on the front edge of the sidepieces that have a double rabbet all around. They make the edge slimmer, at the same time emphasizing it. [caption id="attachment_5684" align="aligncenter" width="340"]Rabbeted Shelf Ends Rabbeting the ends of your shelves can given them an attractive alternate look and replace the need for using more complicated moldings on the outside of the piece. The projection of the shelf leads your eye to the through joints — “the closeup” detail. The positioning and size of these are a good example of proportion at work. The through tenon, like the through dovetail, presents an opportunity to exhibit the skill and workmanship of the maker. Designing the joint to be strong enough for its purpose isn’t a problem. Your decision as to what comes “through” and what doesn’t is called the “layout” — a vital consideration with a through joint. A superbly executed through joint with an unflattering layout is still, in the end, unflattering. [caption id="attachment_5685" align="aligncenter" width="410"]Through Tenons and Rabbets Changing the proportions of your moldings, number of rabbets and creating shadowlines can completely alter the appearance of your piece very easily. The sort of decisions you have to make in the layout of these joints are numerous. First, how many and where across the piece should they be? You could have chosen three singles, edges and center. I chose two twins. Then, how far from the edges does the first joint come? What width to make the mortise? For me, it is dictated by the mortise chisel width. Then, how much space between the mortises, which is affected by how much space between each pair of joints.