Dakota Ultrasonics MINI--MAX - Manual (Page 85)

MINI-MAX Ultrasonic Bolt Tension Monitor
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12) Apply a drop of couplant to the bolt or transducer, and attach it to one
end of the 3” calibration bar.
13) Press the ENTER key and the MINI-MAX will automatically locate and
measure the Ultrasonic Length of the first cal bar.
Note: Rotate the transducer clockwise and counter clockwise applying a
small amount of pressure to eliminate any excess couplant between the
transducer and cal bar surface. Remove and replace the transducer a
couple of times in the exact same location on the cal bar, rotating it each
time to obtain the minimum value measured. Be sure to always place the
transducer in the same location. This will help to eliminate any potential
measurement errors caused by changing the sound path.
Note: Once an echo is found and the MINI-MAX is measuring the cal bar,
the GAIN, as well as the POLARITY may need to be adjusted. The cal
bars produce an extremely strong signal and often the gain should be set to
the minimum 20dB depending on the diameter of the transducer. A
thorough understanding of the section on “Interpreting the Waveform” is
very important prior to making any adjustments. Once this section has
been reviewed, the GAIN and POLARITY features are located in the TUNE
tabbed menu. Alternatively, the gain can also be adjusted in the hot menus
on the main measurement screen.
14) Press the MENU key multiple times to tab right and the ESC key
multiple times to tab left until the CAL menu is highlighted and
displaying the submenu items.
15) Use the UP and DOWN arrow keys to scroll through the sub menu
items until MEASURE ZERO is highlighted.
16) Press the ENTER key to display the Two Point Zero list box.