Kaman ThreadChecker User Manual

Page 8

Kaman Aerospace Corporation

PART NO: 860510-001A

Kaman Precision Products

Last Revised: 6/8/11

Measuring & Memory Systems

217 Smith Street

Middletown, CT 06457

www.kamansensors.com or 860-632-4442

Page 8 of 13

Dwell time and Frequency
When the sensor is being inserted into a hole there is a certain period of ambiguity at
partial insertion. To avoid switching on this ambiguity a form of derivative is used to
determine whether the sensor is in motion or is at the measurement point. The system
will effectively delay of approximately 10-20 milliseconds after it stops moving before it
recognizes the values for the limits (the analog output does not do this and is
continuous). If this delay is too short for the application it can be adjusted at the
factory. If the delay is a problem for the application and there is another method of
determining when a reading is valid then the delay can be turned off by holding down
the button for more than 10 seconds during power up (until the led turns on). It can be
toggled back on by the same method.

Positioning/Mounting the sensor
Ideally the sensor should be just slightly smaller than (and centered in) the untapped
hole. The surface of the sensor tip should be at mid depth.

Larger – For holes that are much larger than the sensor, the mounting can be offset so
that the sensor is near the threaded edge. While this will be able to detect the presence
or absence of a thread there are a couple of limitations. First, only a small section of
the tapped hole is being tested. Second, generally the signal strength is lower. This
results in lower resolution.

Smaller – For holes that are smaller than the sensor, the sensor can be mounted near
the surface of the material and measure down into the hole. The main limitation here is
that there is a limited depth that the sensor can detect threads (near the max range of
the sensor). There is also a limitation on very small holes (where the diameter of the
hole is less than half the diameter of the sensor).