SCEPTRE System
Proportional Displacement Probe


For 16 years EMD's Proportional Displacement Probe has been proving in machine shops around the country that it is versatile, reliable, durable, and accurate.

pdprobe.jpg (7570 bytes)Versatility: It can be configured as a two-axis or three-axis probe. It works in any orientation on CMMs or a variety of measuring instruments, such as flexible gages or machine tools. The probe is designed to work flawlessly with EMD's Indexable Stylus Changer.

The probe can be used for single-point data collection, but the power of the probe is in its continuous-contact scanning capability. It is designed to sense all force vectors acting on the stylus, simulating the human characteristic of "feeling" the workpiece.

This capability allows the gathering of more complete and more accurate information than is possible with the conventional point-by-point method.

Reliability: It has a simple, yet rugged design that means it can handle the toughest working environment, but if you do break it, it's easy to fix -- EMD can repair and return your probe as quickly as 24 hours!

Durability: Its rugged design also means it will last. No wonder the first EMD Proportional Displacement Probe, built over 10 years ago, is still on the job!

Accuracy: It has exceptional resolution: 0.05 µm -- the smallest detectable displacement; and displacement accuracy is 0.1µm after computer calibration. It has a range of ± 3 mm [± 0.125 inch] with an exceptional linear analog signal. EMD's Proportional Displacement Probe has been tested for system accuracy and scanning performance in compliance with ANSI and ISO CMM Scanning Standards to less than 1µm [0.00004 inch].

THE BEST NEWS: EMD's Proportional Displacement Probe costs about half what any other analog probe costs! So call us today and find out how easy and affordable it is for your CMM to begin analog scanning.

The mechanical portion of the probe is made of three cubes that are oriented in mutually perpendicular directions. Each cube is identical to the others, and is made of two right-angle brackets that are connected by eight spring steel wires. A small gap between the brackets allows relative motion between them. The movable bracket can be displaced out of its null position along the direction defined by the open ends of the box, while being positively located in the traverse directions.

A tab on the fixed bracket has two infrared LEDs, which face outward along the axis of travel. The LEDs emit energy, which the photodiodes sense. As the sides of the cube move, one photodiode approaches its LED while the other recedes. Both photo diodes are connected electrically in a differential mode; the change in energy is linear.

The analog signal is amplified at the probe, sent to the machine controller and run through a 16-bit A/D converter. The resulting digital values indicate cube movements, and when all three signals are processed, it is possible to know how much a probe tip has been deflected in 3D space.


PROBE SPECIFICATIONS

  • Measuring Range: ± 3 mm in X, Y, or Z axes with collision protection

  • 17 probe pin mounting locations

  • Force/Displacement ratio: 15 grams per 25 µm [0.001 in.] displacement

  • Internal support system flex wire parallelogram linkages, all axes

  • Probing force range: W to 200 grams, software selectable

  • Position sensors: infrared optical transmitters/receivers, all axes

  • One megahertz internal response rate

  • 12-pin connector and 12-wire shielded cable to controller

  • Power requirements: ±12 Vdc and ± 5 Vdc, < 1 Watt dissipated