Various authors

“ In the details, part A, which is the main body of the instrument, is made of tool steel, the forward or jaw end being solid with the body. This end is hardened, and the jaw ground and lapped. The body is bored out and two flats milled on the outside, which lighten it up and make it neat in appearance. The jaw end is counterbored out with a 45-degree counterbore to form a bearing for the forward end of the micrometer screw. ”

“ The addition to the ordinary micrometer is all at the anvil end of the instrument. The anvil itself is loose and consists of a plunger B, held in place by a small pin A. The pin has freedom to move in a slot in the micrometer body, as shown in the enlarged view in the cut. A spring C holds the plunger B up against the work to be measured, and a screw D is provided for obtaining the proper tension in the spring. The screw and the spring are contained in an extension E screwed and doweled to the body of the micrometer. ”

“ The micrometer screw itself has a travel of one inch, like any standard micrometer. A locknut is used to hold the screw in any desired position. A thumb screw at the end of the barrel bears against the end plug, and zero marks are provided to bring the screw against the plug with the same degree of pressure at each setting. When the head is clamped by means of the locking nut, it is as rigid as though it were solid with the barrel, and the faces of the measuring points are thus always parallel.
Fig. 25. Special Micrometer for Large Dimensions
Combination Micrometer ”

“ All of the tools that have been described require an accurately cut screw, and, as very few lathes are capable of producing this, it may be well to illustrate an indicator for testing the accuracy of the lead-screw, and to explain the method by which it is used. ”

“ The micrometer may be used in combination with a 4-, 6-, 9-, or 12-inch scale. It can be adjusted on standard plugs, or one can make a set of gages up to 12 inches, out of 3/16-inch round tool steel wire, and use these for setting. In mounting the micrometer, before cutting it apart, mill the shoulders shown at A, and in milling the bottom pieces B, use a piece of machine steel long enough for both, cutting the piece in half after milling the slots. In this way one obtains perfect alignment. In a shop where a set of large micrometers is not kept, this arrangement is very useful. [14] ”

“ The work shown is intended for a lathe chuck. The outside diameter of the hub on the work is turned to the same size as the hubs on small faceplates which are furnished with all new lathes. The threaded size is then taken and transferred with a micrometer, over the anvil of which is fitted a 60-degree point as shown enlarged at A. In connection with a graduated cross-feed screw this greatly facilitates the work over the usual cut-and-try method. ”

“ After this the micrometer is locked, and the pieces to be measured are pushed one after another between the face L and the plunger B, the indications of the pointer M being meanwhile observed. Whenever the pointer shows too great a difference, the piece, of course, does not pass inspection. All deviations are easily detected, and any person of ordinary common sense can be employed for inspecting the work.
Micrometer Scale ”

“ Fig. 29 shows a very simple and light five-inch micrometer that can be quickly set to exact position from one to five inches. The round beam is graduated by a series of angular grooves, 1 inch apart, which are of such a form and depth that the clamping fingers at the end of part A spring in, allowing one inch adjustment of the beam to be quickly and positively made. ”

“ The back end of part A forms a spring-tempered split chuck, which grips the beam and holds A in position, while the exterior is threaded to receive the knurled cap B by which the chuck is tightened firmly to the beam. ”

“ No matter how finely and accurately micrometers and verniers may be made, dependence must in all cases be placed on the sensitiveness of a man's hand to obtain the exact dimensions of the piece to be measured. In order to overcome this difficulty and eliminate the personal equation in the manufacture of duplicate and interchangeable parts, the sensitive attachment to the micrometer shown in Fig. ”