“Shaft” is typically used to describe the long narrow portion of a more complex cylindrical component or even a cylindrical part that been turned or machined. Some customers use the term shaft to describe even basic parts that most people would label as pins or rollers.
A measure of the average deviation of a surface from its ideal form. There are many different roughness calculations; the most common is Ra, which is the arithmetic average of the deviations in profile height from the mean line representing the nominal surface, with all of these deviations expressed as positive numbers. Roughness is typically measured in microinches (millionths of an inch) or microns.
Also known as roundness/Diameter Tolerance. The permissible difference between the largest and smallest diameter measurable on one ball.