All of these are profiles of orientation and are used in the exact same way. Perpendicularity describes angularity at 90° and parallelism describes it at 0°. Perpendicularity and Parallelism are actually refined forms of Angularity. The entire variation must not fall outside the tolerance zone. By setting the part at an angle the flatness can now be measured across the now horizontal reference surface. All points on the referenced surface must fall into this tolerance zone.Īngularity does not directly control the angle of the referenced surface it controls the envelope (like flatness) that the entire surface can lie.Īngularity is measured by constraining a part, usually with a sine bar, tilted to the reference angle, so that the reference surface is now parallel to the granite slab. Two parallel planes or lines which are oriented at the specified angle in relation to a datum. The page on Perpendicularity goes into this type of reference in further detail since it is more common with perpendicularity. When angularity is called out on an axis, the tolerance zone now becomes a cylinder around the referenced axis at an angle to the datum. Maximum material condition or axis control can also be called out for angularity although the use in design and fabrication is very uncommon since gauging a hole or pin at an angle is difficult. See the tolerance zone below for more details. The tolerance indirectly controls the angle by controlling where the surface can lie based on the datum. In fact the angle for now becomes a Basic Dimension, since it is controlled by your geometric tolerance. The tolerance does not directly control the angle variation and should not be confused with an angular dimension tolerance such as ± 5°. It can reference a 2D line referenced to another 2D element, but more commonly it relates the orientation of one surface plane relative to another datum plane in a 3-Dimensional tolerance zone. Angularity is the symbol that describes the specific orientation of one feature to another at a referenced angle.
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