Many articles of furniture are costly to ship because they are by nature bulky and prone to damage during transport. Therefore, it has been common to make knock down type mass-market furniture. Knock down furniture is fabricated as components, or sub-assemblies, which can be compactly packaged and economically shipped. The furniture is subsequently assembled by a retailer or a consumer using simple tools, such as common wrenches, screwdrivers, hexagonal wrenches, and the like. Most often such furniture can be subsequently disassembled, if desired. However, the advantages of knock down design will not be realized if such a design compromises the article's appearance or function, or if the article is too hard to assemble.
What constitutes a compromise in appearance for a knock down article depends on an esthetic judgment, and that may vary with the individual. Nonetheless, there are some general principles which may be stated. For example, most people would conclude it is esthetically undesirable to have exposed industrial-type metal fasteners on a wooden chair. Similarly, if the knock down design involved significant changes in the proportions or shapes of the parts of a chair, compared to a traditional chair design which was obviously being emulated, then there would be a high risk that consumers would think the chair looked strange, and they would not purchase it.
A knock down design which compromises function becomes evident when the piece of furniture is put into use. A chair may be subjected to very high loads. For instance, the chair may set on an uneven surface, a user may tilt the chair backward on the rear legs, or the chair may fall over onto a hard floor. Consequently, a knock down chair must not only have strength and rigidity when first assembled, but it must maintain such during its lifetime.
In furniture which is factory-assembled, it is possible to use heavy machinery and special processes. It is possible to use tight fits, diverse fasteners, and special adhesives; all to obtain the strength and durability the product demands. In contrast, by the nature of knock down furniture, there will be joints which must be made by unskilled consumers using simple hand tools. Thus, in some poorly designed knock down furniture the joints will be weak and furniture will be flimsy when initially assembled. In other such furniture, joints will loosen with time or even fail during use. In still other furniture, the knock down design may provide good strength, but be too complex for unskilled consumers to assemble correctly. And of course, a piece of knock down furniture has to be economic to manufacture, otherwise the advantage produced by lower packaging and transport costs, compared to a one-piece factory assembled chair, will be offset.
So, it is not easy to make a piece of knock down furniture which satisfactorily meets all the requirements. Of course, there have been many successful designs of knock down furniture. Specialized fasteners have been developed. However, certain designs of furniture by their nature still present problems which are more difficult to overcome than others. For example, joints which are made at obvious locations can be subject to inherently high stresses, as is the case when a cantilevered back rest of a chair is joined to the chair seat. Therefore, there is a continuing search for new knock down concepts and joint designs.