4.1.2.1 Setting Datum Setting the datum establishes a reference zero height position. Your sample’s length/height is measured based on your established datum. The datum may be established for either tensile or compressive testing. An automatic datuming procedure is included with the spring test software. Tensile Datuming Once your have affixed your testing fixtures, use the jog targets to position the top fixture as close as possible to the bottom fixture. There are two ways you can determine the sample’s free length: 1. If you know the sample’s length from measuring with a caliper or micrometer, you can enter that value into the text block. This value represents the height of the sample and used to determine the datum. 2. Or, you can place the sample into the test fixture. Use the jog key to extend the crosshead upward until a very slight load is displayed on the Controller view. Then press the jog key down to remove all load. Next, press the UP target on the Datum dialog box. The crosshead will automatically move upward at a very slow velocity until a load is detected. Once a load is detected, the height of the sample is known. This height will be used as the basis for all future height measuring in this setup.
Compressive Datuming The automatic datuming feature is used for finding the datum for a compression test. Begin, by manually positioning the top and bottom fixtures very close to one another, but not touching.
CAUTION Use extreme care and the slowest jog speed when placing the top and bottom fixtures together to avoid overloading your load cell sensor.
Once the top and bottom fixtures are close together, press the H target on the Controller view. This will cause the crosshead to automatically move until the top and bottom fixtures touch. A slight load, indicating that the top and bottom fixtures have touched will automatically stop crosshead movement. This will establish the datum position. Next, manually move the crosshead upward so that there is sufficient room between your top and bottom fixture to properly fit your sample for testing.
NOTE You do not need to repeatedly set the datum during a batch. The datum is remembered by the system.
Select Up for extension spring datuming. Touch the Up target, the crosshead will move upward until the extension datum is determined automatically.
Select Down for compression spring datuming. Touch the Down target and the crosshead will move downward until the top/bottom fixture touch and the datum is determined.
Shows automatic Datum feature dialog
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