The LEGEX structure quickly attenuates traverse-induced vibrations and so reduces any adverse effect on measurements. 

This characteristic also allows ultra-high scanning accuracy to be realized.

The LEGEX uses a fixed-bridge type structure. This is the ideal CMM architecture and virtually eliminates pitch and yaw errors. Most other CMMs use a moving-bridge design with a single drive unit under the column, which tends to cause yawing and pitching during slide movements.

• Fixed-bridge type structure.
• Moving-bridge type structure.
• The center of gravity of a moving bridge moves according to the X-axis motion. This movement of the bridge center of gravity changes the load distribution and therefore alters the consequential deformations.

The fixed-bridge design of the LEGEX allows the axes to operate totally independently. Movement of the X-axis slide does not change the loading on the Y-axis slide, and so does not cause deformation. 

Also, the ‘center of gravity’ type drive system places the drive units near the center of gravity of each slide. This feature allows very high speed, highly accurate measurements by reducing inertia-induced deflections during acceleration and deceleration.

The LEGEX is hardened against floor induced vibration by use of ‘air-damped spring isolators’ with an auto-leveling function. This virtually eliminates factory floor vibrations from the entire machine structure.

To reduce the effects of internally generated vibration, the LEGEX uses a special floating mechanism to couple each ballscrew to its guide block. This isolates the slide from the servo motor as it turns the ballscrew and thus prevents transmission of motor vibrations, especially during acceleration and deceleration.

The LEGEX is equipped with crystallized-glass scales with a

resolution of 0.01μm and an ultra-low linear expansion coefficient of 0.01 x 10-6/K. This virtually zero thermal expansion coefficient means the LEGEX can maintain its extreme accuracy in spite of thermal changes.

The scales are also mounted in a unique new way that reduces the hysteresis error to 1/5 that of previous models. The graphs below show the reduction in hysteresis error that results from this new mounting method.

While conventional very high accuracy CMMs require fairly strict temperature controlled environments, the LEGEX has been designed to improve the thermal stability of each component to minimize deformation. In addition, temperature sensors on each axis and for the workpiece itself detect temperature changes in real time and are used to compensate back to size at 20ºC.

Our proprietary control unit has been upgraded with sophisticated control technology that uses a new algorithm. A newly developed high-resolution linear encoder is also used to achieve higher accuracy.

Generally speaking, temperature compensation and thermally insensitive materials can widen the usable range of ambient temperature and gradients. To eliminate a common source of temperature variation, the LEGEX incorporates a special air-server. In addition to the standard air cleaning and drying functions, this air server stabilizes the temperature of air drawn from the factory air supply to 20ºC±0.1ºC. 

In combination with the machine-enclosure design and thermally insensitive glass scales, temperature-stabilized air supplied to the air bearings can produce the exceptional thermal isolation needed for low measuring uncertainties. This air supply is also used for the MPP-300 probe to provide stabilized scanning.