2-1.2 Operation of Trendsetter™ with LVDT Electronic Probes
Using the power switch located at the rear of the column, turn the unit on. Depending upon your
application, select the input channel as required: A, B, or AB. Next, check the Inch, Metric, indica-
tor light to see if the gage is set to the required measurement system. Depress the contacts on the
probe to see if the column moves in the correct direction for the movement of the contacts; i.e., for
an O.D. measurement, a large part will cause the probe tip to move in. Any depression on the probe
tip should move the bargraph display in an upward direction. If either of these functions is incorrect,
remove the module as follows: switch the column off, unscrew the two module retraining screws,
and gently pull the module out. Do not touch the matrix I/O pin headers; the function of these units
can be found later in this write-up.
Check that the Inch and Metric Pin Headers as well as the polarity switches are in their correct
position. Replace the module by lining up the top and bottom edges of the board with it’s card
guides and sliding back until it locates in its electrical socket. Screw in the two module retaining
screws to secure the module and switch power on. The full scale range of the readout should now
be set.
To select a range, if it has not already been decided, it is best to select one that is two to three
times greater than the tolerance being checked. This will allow for good approach and oversize
range. If parts are being matched or segregated into classes and are all in tolerance, much more of
the full scale range can be used.
Set the range knob to the desired value. The corresponding digital scale values will be shown
alongside the bargraph scale. The setup is now ready for mastering.
2-1.3 Mastering
There are two basic approaches to mastering:
1.) Min. and Max. masters
2.) Mean or zero master
Setting to a Mean Master
Place the mean master in a fixture and turn the zero knob to bring the scale to zero or to the actual
calibrated size of the master.
Setting to Min. & Max. Masters
Place the max. master in the gage and, with the zero knob, adjust the column to the upper limit
reading. Remove the max. master and replace with the min. master. The reading should rise to the
lower limit. If, due to a poor initial calibration (or a non 1:1 ratio in the lever arms of the gage), the
lower limit is not achieved, the magnification should be altered.
2-1.4 Front Panel Magnification Trim
Place one master in the gage. Set one limit at the desired point with the zero knob. Apply the other
master and, with a small screwdriver, adjust the recessed “mag” screw until the column moves to
the desired point. Reapply the other master and, if necessary, readjust until both masters move the
column the required amount. This front adjust screw will allow for a trim of approximately 20% and
will change all inputs; A, B, and AB.
In some cases, where transducers other than Edmunds’ gage probes are being used, or where
levers change the 1:1 ratio of input to output, the rear adjustments on the circuit board may need to
be used.
5