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.
A drawing desk is in its antique form, a kind of multipurpose desk which can be used for any kind of drawing, writing or sketching on a large sheet of paper or for reading a large format book or other oversized document or for drafting exact technical illustrations. The drawing table used to be a frequent companion to a platform desk in a gentleman’s study or private library, during the preindustrial and early industrial era. More recently engineers and draftsmen use the drawing board for making and modifying drawings on paper with ink or pencil. Different drawing instruments (set square, protractor, etc.) are used on it to draw parallel, perpendicular or oblique lines. There are instruments for drawing circles, arcs, other curves and symbols too. However, with the gradual introduction of computer aided drafting and design (CADD or CAD) in the last decades of the 20th century and the first of the 21st century, the drawing board is becoming less common.
A drawing table is also sometimes called a mechanical desk because, for several centuries, most mechanical desks were drawing tables. Despite of Computer aided drafting, many graphic designers, artists, architects and even some structural designers still rely on paper and pencil graphics produced on a drafting table. Modern drafting tables typically rely on a steel frame. Steel provides as much strength as the old oak drafting table frames and much easier portability. The steel frame allows mechanical linkages to be installed that control both the height and angle of the drafting board surface. The drafting table surface is usually covered with a thin vinyl sheet called a board cover. This provides an optimum surface for pen and pencil drafting. It allows compasses and dividers to be used without damaging the wooden surface of the board. A board cover must be frequently cleaned to prevent graphite build up from making new drawings dirty. Some drafting tables incorporate electric motors to provide the up and down and angle adjustment of the drafting table surface. These tables are at least as heavy as the original oak and brass drafting tables and so sacrifice portability for the convenience of pushbutton table adjustment.