Show keeping gp U p wi cien e S C jin e r V e 0 science service service device that tests surface accuracy Is mechanical anical mar marvel vel by WATSON DAVIS nev neri york A human hair about 15 feet across that is what it would be if it were magnified with one of the latest testing devices for auto nobble parts one of the wonders ot of modern mechanical engineering Is the routine if ne measurement of finely finished surfaces tur faces so smooth that magnification of the order of times is cec necessary essary so exacting have become come e the demands ot of modern modem machine chine e shop practice that the working surfaces faces lur of antifriction anti friction bearings for or instance require great accuracy and smoothness surface irregularities I 1 less e ss then than a hundred thousandth 11 an inch 10 micro inches are cause tor for rejection A machine that measures so finely with the rapidity necessary in actual product production lon has been achieved the profil ometer as it is called has a tiny point that traces the most molecular surface irregularities this varies the current flowing through a magnet and this current is sent through special amplifiers and circuits thus electrically there is created that high magnification necessary record written by light th the e magnified replica ol of the surface desired is the light written record of the into wh which lc h the ahe current is fed it if a permanent record Is desired a motion picture camera is aimed at the waving light line of the how tar far machine shop precision has traveled during the age of power will be realized when it is recalled that watt inventor of the steam engine was elated when he found that wilkinsons Wilkin sons boring mill could machine an engine cylinder true to within the thickness of a shilling the dawn of precision in machinery came when the system of interchangeable parts was adopted early in the last century arms factories in connecticut pioneered to in measuring accurately with gauges with accuracy increased many told this is the principle that underlies the machine age of today |