MARVELS OF MINUTE WORKMANSHIP.

Waipawa Mail, Volume XXXVII, Issue 8417, 10 December 1920, Page 1 (Supplement)

MARVELS OF MINUTE WORKMANSHIP.

\CHINE THAT SEEMS TO PERMI RAGLES. Most of us carry two remarkable penmens of minute workmanship, bey are both contained in our itch, if that article is of the ordinrv pattern. One is the name of the maker on je dial. This lettering, though only bout 1-4Oin. in height, is painted on , hand. \Ve are indebted to machinery for pe other miscroscopic feature. Look, ritfi a glass, at some of the screws, ad you may find that the heads of je smallest are only 3-100in across nd that the threads are sunk mere-2-100in. This is fine work; but much more 3 is thaj in tiny watches which are pcoiporated in rings or ear-rings. Amazing accuracy Is attained, too. B the everyday manufacture of comioii things. By a whirring emery he' 1 parts of a motor-car engine are rought to within l-3,000in of stanard size, and the slit in a pen is iad by two blades adjusted with tch nicety that the thinnest possible lm of moisture on the lower one rould be removed by the other in pising it. Still more remarkable is the fineiess seen in the gauges called for in Bass production. This practice indves interchangeability of parts, ad consequently a rigid adherence standard is imperative. In some arks there are great heaps of parts rhich do not vary from one another uore than l-2,000in —a result which ould be impossible without a series f beautiful gauges. The care exercised in connection ith such gauges would amaze the ninitiated. Periodically the working luges are tested by master gauges, Hue of which are so exquisitely fine Sat they must be used quickly lest ley be affected by the heat of the and. These gauges are made of steel Inch has been thoroughly “ripened" r matured. New steel cannot be led, because It may splinter of its wn accord, or, if it is worked up to ertain dimensions, become distorted he very next day. Marvellous is the accuracy of mas--r guages—which only the most kilful craftsmen can make. Not mg ago, for instance, some were anted in connection with the mass roduction of aeroplane engines, and was necessary that they should be within l-5,000in of standard. They ere made, though at great cost. The i°n who produced them had to be arefully watched, and sent heme for rest if they seemed to be ever so ttle “off colour."

No less astounding are the details :a some machines. One invented by Sir Joseph Whitworth will detect a length variation of one millionth part of an inch. If you touched for la instant with your finger-nail a 36 la bar of steel, the expansion in it cue to the heat would not be too •light to be registered by this piece mechanism. TRY THIS TEST. There are other machines which [•lit the draughtsman out of the running for certain work. How many ;»aral! 1 lines can you draw in an inch? If you are. very skillful, you nay manage 150, or perhaps 200. But there is one machine that will rule 120,000 to the inch, and another ij capable of ruling fourteen in a s>ace equivalent to the thickness of tibsue-paper. An error so small as to bo nearly by the lay mind is fatal io success with these machines. If either was “out" only 1-300,0Q0in., it Tould not work satisfactory. Minute care, however, is not peculiar to small work only. For in the taking of a 12in. gun a shaving iken off a tube may be merely 1-500 b. thick.