When you use a disk stylus in an analog contact probe, the 2D algorithm that calculates the resulting deflection matrix has a restriction. It requires four equally spaced hits on the equator with 90 degrees between them to cover 270 degrees of the sphere. When stem avoidance is required, it automatically starts at 45 degrees and stops at 315 degrees. This allows for enough room on both sides of the stem while still covering the required 270 degrees. The algorithm does not allow for a reduction in sphere coverage. If the range of 45 to 315 degrees is not enough to avoid collision with the stem, it will be necessary to use some type of physical avoidance. Some options are:

• Use a sphere with larger diameter

• Use a stem with a smaller diameter

• Use a different stem angle

Choose an option that provides sufficient clearance to avoid collision.