The Purpose of an Engineering Ruler

The engineering profession is the practice of designing, building and maintaining structures, property, systems, devices and specialty processes by incorporating practical theories and knowledge, scientific and economic applications and principles, such as math and science. The result of the practice is to provide a solution to a problem or an objective on which to build the future.

Engineers often work with drawings that are drawn to scale or a fixed ratio in length. That means the drawing is a smaller version of the full-size plan. In most cases, it is impractical, if not impossible, to draw a plan to full scale, especially if the property or building involved is many acres or hundreds or thousands of feet in size.

The measuring device used to create the engineering drawings is called an engineering ruler or engineers scale. They are available in different lengths such as 4” and 6” pocket size scales and 12”, 18” and 24”. The most common length of a scale is 12”, but longer scales are available to measure greater distances with more accuracy. The scales are made from a variety of materials including wood, plastic, bamboo and aluminum. They are single, double or triple sided and usually have a beveled edge to lie flat along the plan, making it easier and more accurate to measure distances.

The most common scales are available in different graduations such as 1”=10’, 20’, 30’, 40’, 50’ and 60’. There are scales available in 1”=80’, 100’, 200’, 300’, 400’ and 600’. Sometimes an odd graduation might be needed such as 1”=15’. The 30 scale can be used by dividing the length measured in half, but if 15 scale will be used a lot, makers of scales and engineering measuring devices might manufacture one at a reasonable cost.

The engineering scale is marked in lengths according to the ratio of the scale. The ends of the scale are left unmarked to avoid losing the markings if the scale is dropped and the end chips away. When measuring one inch, the scale will show whatever the measuring ratio is such as when using the 1”=20’ scale, when measuring one inch, the scale will show 20 feet. Using the different engineering rulers will prevent mistakes that can be made when converting the measurement in inches to the appropriate feet.

The scales are ticked off in 10 foot increments with 1 foot markings in between. If a half foot measurement is needed, that has to be done by eye, but with the smallness of the scale, the measurement can still be accurate.

The engineering ruler is a basic tool used by all engineers, draftspersons and architects and landscape architects and contractors. Cost estimators and specification writers use the scales when preparing cost estimates and construction specifications. Scales are used in the office and in the field, as well. Engineers spend a lot of time at project sites during the construction phase and will often review the plans and specs with the contractor of check the plans if an error is suspected.