Scale Drawing
A scale drawing is a drawing that represents a real object. The scale of the drawing is the ratio of the size of the drawing to the actual size of the object. Plans are usually type of "scale drawing", meaning that the plans are drawn in specific ratio relative to the actual size of the place or object. Various scales may be used for different drawings in a set.
An architect's scale is a specialized ruler. It is used in measuring from reduced scale drawings, such as blueprints and floor plans. It is marked with a range of calibrated scales (ratios).For accuracy and longevity the material used should be dimensionally stable and durable. Scales were traditionally made of wood, but today they are usually made of rigid plastic or aluminum. Architect's scales may be flat, with 4 scales, or have a symmetric 3-lobed cross-section, with 6.
An engineer's scale is a tool for measuring distances and transferring measurements at a fixed ratio of length. It is commonly made of plastic and is just over twelve inches (300 mm) long, so that the measuring ticks at the edges do not become unusable by wear. It is used in making engineering drawings, commonly called blueprints, in scale. For example, "one-tenth size" would appear on a drawing to indicate a part larger than the paper itself. It is not to be used to measure machined parts to see if they meet specifications. The engineer's scale came into existence when machining parts required a greater precision than the usual, binary fractionalization of the inch as in the architect's scale for houses and furniture. They were used, for example, in laying out printed circuit boards with the spacing of leads from integrated circuit chips as one-tenth of an inch.