HAMAR LASER STEALTH Series, General Training Manual

Page: 104 / 113

100
Adjusting the Horizontal Trimpot
If you are using Model R-307 Readout, the horizontal axis display may also require calibration.
1. Turn the horizontal axis micr.025 in. (one full turn)
Turn the horizontal axis micrometer control one full revolution (+.025 in.). Be sure to eliminate
micrometer backlash.
2. Adjust the Slave Gain (Horizontal Input Trim Screw)
While watching the numbers in the Horizontal window of a readout, use a flat-head screwdriver to
adjust the set of the Slave Gain (Horizontal input trim screw). Turn the screw until numbers in the
vertical display read 25.0 on the .0001 scale.
3. Re-zero the micrometers
4. Turn the horizontal axis micrometer -.025 in. (one full turn)
Turn the horizontal axis micrometer control one full revolution (-.025 in.). Be sure to eliminate
micrometer backlash.
5. Read and record the number on the readout display
6. Adjust the Slave Gain (Horizontal Input Trim Screw)
If the readout display shows -25.4 for a micrometer move of -.025 in., adjust the Slave Input Trimpot
until the readout shows (-25.0 + -.07) = -25.7.
While watching the numbers in the Horizontal window of a readout, use a flat-head screwdriver to
adjust the set of the Slave Gain (Horizontal input trim screw). To trim out half of the difference
between the displayed move and the micrometer move, adjust the trimpot so that the numbers in the
vertical display read with half of the error removed. By adjusting the -26.4 display reading to -25.7,
you can trim out half the error on the readout display for an -.025 micrometer move. Turn the trimpot
screw until numbers in the horizontal display reads out with half of the error removed (
-25.7
on the
.0001 scale). This number represents the closest possible calibration to a true reading of -.0257 in.
Trimming out the entire H+ reading error eliminates the major difference between the micrometer
move and the readout display. During the H- adjustment of the calibration trimpot, the remainder of
the vertical axis calibration error has been removed by changing the span to balance the H+ and H-
readout error. After adjustment, the readout display will show a smaller amount of error for both H+
and H- readings.
Note:
Following this procedure will allow readout calibration as perfectly as possible with an analog
electronic device.
7. Re-zero the micrometers
Calibration of the readout is complete when numbers on the vertical/horizontal axis readout windows
fall within 5 percent of corresponding micrometer moves.
8. Close the R-307 Readout housing and tighten all screws.