Some ideas:
a) Try using your scale differentially to check your scale and technique by measuring the side weight of a clearly marked ball, then repeating the process in the opposite direction
b) Compare the balance measurements you get with another pro-shop's scale, or one of our digital scales
c) Keep a calibration ball in-house to periodically check your scale's accuracy and trainee technique.
Many pro-shop operators think that the balance beam scale measures the relative weights of the two halves of the ball. This is not the case. The balance beam scale measures the relative LEVERAGE of the two halves.
Since the USBC standard has been based upon the balance beam scale, our digital scale (which actually DOES measure the weights of the two halves) has a built in calibration for this.
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Dr. Douglas G. Frank, President
Precision Analytical Instruments, Inc.
www.ToolsForAnalysis.com