Workshop Hints for Munition Workers

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Bernard Edward Jones
Cassell, 1917 - Ordnance - 156 pages
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Page 116 - To read the caliper, therefore, multiply the number of vertical divisions visible on the sleeve by 25, and add the number of divisions on the bevel of the thimble, from 0 to the line which coincides with the horizontal line on the sleeve. For example, as the tool is represented in the engraving, there are seven divisions visible on the sleeve.
Page 115 - One complete revolution of the spindle therefore moves it longitudinally onefortieth (or twenty-five thousandths) of an inch. The sleeve D is marked with 40 lines to the inch, corresponding to the number of threads on the spindle. When the caliper is closed, the beveled edge of the thimble coincides with the line marked 0 on the sleeve, and the 0 line on the thimble agrees with the horizontal line on the sleeve.
Page 114 - The spindle C is attached to the thimble E, on the inside, at the point H. The part of the spindle which is concealed within the sleeve and thimble is threaded to fit a nut in the frame A. The frame being held stationary, the thimble E is revolved by the thumb and finger, and the spindle C being attached to the thimble revolves with it and moves through the nut in the frame, approaching or receding from the anvil B. The article to be measured is placed between the anvil B and the spindle C.
Page 115 - ... (or twenty-five thousandths) of an inch. The sleeve D is marked with 40 lines to the inch, corresponding to the number of threads on the spindle. When the caliper is closed, the beveled edge of the thimble coincides with the line marked 0 on the sleeve, and the 0 line on the thimble agrees with the horizontal line on the sleeve. Open the caliper by revolving the thimble one full revolution, or until the 0 line on the thimble again coincides with the horizontal line on the sleeve; the distance...
Page 116 - When the caliper is opened, the thimble is turned to the left ; and when a division passes a fixed point on the barrel, it shows the caliper has been opened one-thousandth of an inch. Hence, when the thimble is turned so that a line on the thimble coincides with the second line (end of the first division) of the vernier, the thimble has moved one-tenth of the length of one of its divisions, and the caliper opened one-tenth of one-thousandth, or one ten-thousandth of an inch.
Page 116 - Accordingly, when a line on the thimble coincides with the first line of the vernier, the next two lines to the right differ from each other one-tenth of the length of a division on the thimble ; the next lines differ by two-tenths, etc.
Page 115 - The beveled edge of the thimble is marked in twentyfive divisions, and every fifth line is numbered, from 0 to 25. Rotating the thimble from one of these marks to the next moves the spindle longitudinally...
Page 115 - The pitch of the screw threads on the concealed part of the spindle is 40 to an inch. One complete revolution of the spindle therefore moves it longitudinally onefortieth (or twenty-five thousandths) of an inch. The sleeve D is marked with 40 lines to the inch, corresponding to the number of threads on the spindle.
Page 65 - The cutting edges must make a proper and uniform angle with the longitudinal axis of the drill ; they must be equal in length, and the lips of the drill sufficiently backed off for clearance, otherwise they will not cut easily, or they will make a hole larger than the size of the drill. Drills properly made have their cutting edges straight when ground to a proper angle, which is 59 degrees, as in Fig.
Page 91 - ... cut. In working change wheels express the ratio between the lead of the screw to be cut and the lead of the leading screw in the following manner : Lead of screw to be cut Drivers. Lead of lead screw Driven...

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