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Statistics and Accuracy
It is important to remember that more calibration measurements provide better statistics and better
calibration, especially if a wide range of roughness is used in the calibration. It is also important to
remember that stylus gages measurements often lack repeatability depending on surface uniformity, the
environment the measurement is taken in, condition of the instrument and condition of the actual stylus tip.
It is a good idea, therefore, to take a few stylus gages measurements for each sample and enter the average
of those values into the spreadsheet.
Instructions for using the Setup File and Calibration Template.xls
The spreadsheet is designed to step you through the calibration process from "Step 1" through "Step 6".
Lasercheck calibrations often show three regions of correlation. There is an exponential correlation on
smooth surfaces (a few microinches of roughness), followed by a linear correlation region (from a few
microinches to 10’s of microinches of roughness), followed by a final exponential correlation region (10’s
of microinches to approximately 100 microinches of roughness). The spreadsheet instructions will allow
adjustment of calibration correlation curves in each of these regions to provide the best fit to the calibration
data.
Step 1 Enter Ra Values
Below is an image of the Step 1 tab of the spreadsheet including instructions.
