Experimental Comparison of Scalar and Digital Micrometers

Abstract

Three digital micrometers (two German and one American) were compared for speed and accuracy of reading, using as subjects 89 journeymen and 16 apprentices from the engineering industry. It was found that untrained apprentices performed very badly on the Standard micrometer, but on two of the digital micrometers they were substantially more accurate than either the trained apprentices or the journeymen using the Standard micrometer; the latter made on the average 3-7 per cent errors, the great majority of these being misreadings by 5, 10, 25 or 100 thous. These same journeymen using digital micrometers made errors of 005 percent. Manipulation and reading time on the digital micrometers was less than on the Standard, one being 25 per cent less

A supplementary analysis by age showed that, contrary to expectation, the performance of an older group of subjects, aged between 50 and 64 years, did not improve more with the use of digital micrometers than that of the younger subjects. In fact, their performance improved the least.