Inscribed Circle

The Inscribed Circle function evaluates the data points used to measure the circle and locates the Minimum and Maximum Inscribed circle solutions. The minimum Inscribed Circle is best used to illustrate a gage pin being inserted into a bore. The gage pin, when sized to the largest pin available to fit in the bore, will represent the minimum inscribed circle. The pin will contact the bore at three points representing the closest points of contact.

The maximum Inscribed Circle is best suited for use on outside features such as a boss. This feature is best illustrated when using a ring gage to measure an outside diameter. The solution is the smallest ring gage that will fit over the outside diameter. The ring gage will contact the diameter at the three greatest points.

In both cases, the diameter reported will reflect these conditions. The position will also vary from the normal best-fit solution of a circle.

figure 1, Activating

The Inscribed Circle feature is a post operation on an already measured or constructed 2D circle. To use, highlight the circle in the inspection report and right click to activate the sub menu, see figure 1. Locate either the Minimum or Maximum Inscribed Circle feature as required.

Once you select your choice, the circle will appear in the inspection report as an Inscribed Circle, see figure 2. In most cases, we recommend that you perform a recall on the original circle, then apply the Inscribed Circle feature. That will preserve the original values for comparison.

figure 2, Reported Inscribed Circle

If you require removing the Inscribed Circle feature and revert it back to a normal best-fit circle highlight the Inscribed Circle in the report and right click to activate the sub menu. Choose "Remove Inscribed Circle".

An Inscribed circle can have all tolerance values applied. The actual values will reflect the characteristic of the revised solution caused when applying Inscribed Circle. All construction, PCS components and tags for SPC will reflect the revised values.