The height gauge or dial indicator is then used to measure the distance between the two parts at various points along their surfaces. To measure parallelism, two parts are placed on the surface plate, with one part resting on top of the other. Parallelism is also typically measured using a surface plate, along with a height gauge or dial indicator. In other words, parallelism measures how closely two surfaces are aligned with each other. Parallelism refers to the degree to which two surfaces are perfectly parallel to each other. The flatness of the surface is then calculated by comparing the readings taken at each point to determine the deviation from the perfect flatness. The readings are taken at different locations across the surface of the part to ensure that it is uniformly flat. To measure flatness, the part being measured is placed on the surface plate and a dial indicator is used to measure the distance between the part and the surface plate at various points. A surface plate is used as a reference surface, against which the flatness of a part can be measured. Flatness is typically measured using a surface plate, which is a large, flat piece of granite or cast iron.

A flat surface has no high points or low points, and is completely even. Additionally, flatness is typically measured using a surface plate and a dial indicator, while parallelism is typically measured using a surface plate and a height gauge or dial indicator.įlatness refers to the degree to which a surface is perfectly level and smooth. In other words, flatness is an individual property, while parallelism is a comparative property. Flatness measures the degree to which a single surface is level and smooth, while parallelism measures the degree to which two surfaces are aligned with each other. While flatness and parallelism are related, they are not the same thing. The straight parallel bands, and not the width of light band indicates the flatness. Lapping plate convexThe control rings must be moved to the inside of the plate to correct this condition

Surface flatness symbol