Diamond blades are tensioned by the manufacturer to run true at the recommended rpm, which is stamped on the blade. Tensioning is designed to keep blades from distorting at high speeds. The blade is manufactured in the form of a dish that will straighten when the blade is rotated at optimum speed. The dishing is small, about 0.0005 inch per inch of diameter. The tensioning can be accomplished by a mechanical roller tensioning machine or a hammersmith. This process is especially critical for blades of larger diameter (more than 24 inches). If the design speed is not achieved, the blade will tend to wander as cutting begins. When a blade is said to be out of tension, the amount of dish is not correct. Such a blade wobbles while out of the cut, and it wanders when placed in the cut. An out-of-tension blade cannot be made to cut a straight line.
