In this article, I wanted to go beyond the simple go/no go measurements that most air gaging is used for. Air gaging is a highly effective and efficient way for measuring these simple diameter requirements. It is also extremely repeatable on tight tolerances, but for this article, I wanted to focus on using air gaging to measure form requirements such as roundness, flatness, perpendicularity/squareness, taper, straightness, matching, and others.
So, let us dive into how air gaging can be used to measure some of these other form requirements. Before I get into how specifically these gages are designed and work, I should state that a lot of these form dimensions are reliant on the display unit or operator to keep track of the MAX and MIN and then the delta of MAX-MIN. A lot of the more modern display units will keep track of this for you, making these calculations quite simple to achieve. As an example: Roundness would require you to know the MAX and the MIN value and do simple math of MAX-MIN to achieve your roundness dimension. As stated above, the display unit can keep track of this for you or the operator can watch on the screen and visually see the MAX and the MIN and do the math in their head.