Dimensional Information on Engineering Drawings

Abstract

Two experiments are described which attempt to show how the lay-out of dimension values on engineering drawings affects the ability of people reading them to extract specified values accurately and rapidly. Undorgraduates, engineering draughtsmen, inspectors and patternmakers took part by answering simple factual dimension questions set for a series of engineering drawings of actual components. Drawings of a simple and a complex component were presented, each with various dimension lay-outs and, or, types of question format. The results showed that the degree to which performance was subject to random influences was almost wholly dependent on the precise form of question posed about a drawing feature. In particular, it appeared that uncertainty about which of several alternative and likely locations was relevant for a specified value led to highly variable performances. Effects of dimension lay-out were largely swamped by this effect but the evidence indicates that a hybrid abstracted form of dimension la...