. Railway mechanical engineer . asoline, alcohol and otherliquid and all sediment deposited from the atmosphere. Afterthe contacting surfaces have been washed and thoroughlydried with a clean cloth or with new clean tissue paper, themicrometer is inserted in the hole and the jaws expandeduntil they are stopped by the walls of the hole, thus measur-ing the exact size of the lapped hole. After having found the exact size of a hole, with the sur-faces clean and dry, it is astonishing to note the changeswhich take place when oil or lubricant is present. Oil ofany nature reduces the friction which
. Railway mechanical engineer . asoline, alcohol and otherliquid and all sediment deposited from the atmosphere. Afterthe contacting surfaces have been washed and thoroughlydried with a clean cloth or with new clean tissue paper, themicrometer is inserted in the hole and the jaws expandeduntil they are stopped by the walls of the hole, thus measur-ing the exact size of the lapped hole. After having found the exact size of a hole, with the sur-faces clean and dry, it is astonishing to note the changeswhich take place when oil or lubricant is present. Oil ofany nature reduces the friction which caused the screechingand jerky movement, found when the micrometer was rotatedin the ring, clean and dry. Oil makes the rotation of themicrometer smooth, and with oil present it is no longer pos-sible to distinguish the large diameters from the small diam-eters-; the high points from the low points. Furthermore, themicrometer can be expanded to be several ten-thousandthslarger than the hole, and no appreciable difference in the. The 2-ln. Bath Internal Micrometer force required to rotate the micrometer will be noticed. Oilentirely destroys feel. An excellent way to detect small irregularities such asdepressions, high spots and slight conditions of bell mouthor taper in a lapped hole is to make use of a very thin filmcontaining sediment or residue deposited from the air. If alapped ring gage is first coated with castor oil, the excess oilbeing removed by vigorous rubbing with a clean cloth andthe gage is allowed to stand for several hours, dust particlesfrom the air will be deposited on the trace of oil left in thering. A micrometer rotated in a ring treated in the foregoingmanner develops a very thin brownish colored film by whichit is possible to detect minute irregularities in holes. It issaid that with the new Bath micrometer internal measure-ments can be made even more accurately and rapidly thanexternal measurements with the usual form of micrometer.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
