by Joseph P. Fuehne, Ph.D., P.E.
The Purdue Polytechnic Institute in Columbus utilizes metrology tools with targeted measurement artifacts, which may be 3-D printed or machined, to facilitate learning and provide opportunities to demonstrate competency in basic measurement tools. Analog and digital calipers, analog and digital micrometers, Pi tapes, bore micrometers, and dial indicators are all demonstrated and employed during these training sessions. Trainees are required to complete measurement forms that are developed using a spreadsheet program and submit those completed forms for assessment. An element of the training involves using different tools to measure identical features on a part, highlighting the different scales, resolutions, potential errors and uncertainties, as well as the obvious ease or challenge to utilize each tool. A digital dimensional measurement tool has obvious advantages due to the ease of reading the value, but it may not always be the best tool for the specific measurement. Those who have little experience in measurement may tend to believe the value on the tool without considering appropriate procedures, units, and mechanics of actually using the tool – pressure applied to the measurement surface, proper zero-setting of the tool etc. In the case of measuring diameters, is there consideration and evaluation of using a two-point instrument versus a three-point instrument? These issues are highlighted only if different tools are used to measure the same feature and the values are recorded.
