大香蕉2018不卡在线_大香蕉2018九六攻摄_大香蕉2018亚洲东京热_大香蕉2018亚洲免费观看

THREE:In the manufacture of machines, there are usually so many sizes and modifications, that drawings should assist and determine in a large degree the completeness of classification and record. Taking the manufacture of machine tools, for example: we cannot well say, each time they are to be spoken of, a thirty-six inch lathe without screw and gearing, a thirty-two inch lathe with screw and gearing, a forty-inch lathe triple geared or double geared, with a twenty or thirty foot frame, and so on. To avoid this it is necessary to assume symbols for machines of different classes, consisting generally of the letters of the alphabet, qualified by a single number as an exponent to designate capacity or different modifications. Assuming, in the case of engine lathes, A to be the symbol for lathes of all sizes, then those of different capacity and modification can be represented in the drawings and records as A1, A2, A3, A4, and so on, requiring but two characters to indicate a lathe of any kind. These symbols should be marked in large plain letters on the left-hand lower corner of sheets, so that the manager, workman, or any one else, can see at a glance what the [86] drawings relate to. This symbol should run through the time-book, cost account, sales record, and be the technical name for machines to which it applies; in this way machines will always be spoken of in the works by the name of their symbol.