Probably rotation, units in Arc-seconds I presume.

-AK2DM

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"It's the questions that drive us"
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Often in geometry w (usually a lowercase w) is the rotation factor about the z axis. (Lowercase u would be rotation about the x axis, and v would be rotation about the y axis.)

At least I know this is true according to the ASME Y14.5 standard, so if this CMM stuff in any way relates to GD&T then that might be the answer.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

Just for informational purposes...in machining, the respective rotations around x, y, and z are a, b, and c.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II

The w-axis can be a tertiary axis movement parallel to the z-axis. An example is a horizontal boring machine. The spindle movement in and out is the z-axis. While the table movement parallel to the z-axis is the w-axis. On your CMM. The w-axis may be a rotational axis. It probably depends on the machine tool builder. Turn you position display on and jog the w-axis and see what motion is being performed. You could also check with the CMM builder.

Bill