# Industrial Mathematics Practically Applied; An Instruction and Reference Book for Students in Manual Training, Industrial and Technical Schools, and for Home Study

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## Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...motion of the index plate takes place when the crank is turned, which turns the plate either forward or backward as may be required. The result is that the actual movement of the crank, in indexing, is either more or less than the movement in relation to the index plate. The differential method cannot be used in connection with spiral milling, because the spiral head spindle is geared to the lead screw of the milling machine. The amount of rotation of the index plate may be regulated by the difference in velocity ratios of the change gears. Example: Find the indexing required for 81 divisions. Solution: By simple indexing the index crank would be rotated through 40/81 of a turn for each division, but as there is no plate with 81 divisions, the spacing is impossible: therefore another fraction is selected whose value is near 40/81, say 40/84 or 10/21, then a 21 hole circle can be used, indexing in this way for 81 divisions, giving 81 X 10/21 = 810/21 or 38 12/21 complete turns of the index crank or 1 9/21 turns less than the 40 required for one complete turn of the work. By using gears in the ratio of 1 9/21 to 1, the index plate will make I 9/21 revolutions, which with 38 12/21 turns of the crank will make the 41 turns required. Thus the gears will be in the ratio of 7X3 56 X 24 drivers If the motion of the index plate must be in the direction opposite to the movement of the index crank, idler gears must be used. The following gears are generally available for differential indexing: 24-24-28-32-40-44-48-56-64-72-86-100. Angular Indexing With the standard index head, where 40 turns of the index crank are required, for one revolution of the work, one turn of the crank equals 1/40 of 360 deg. or 9 deg. Thus, if one complete turn of the index...show more

## Product details

• Paperback | 54 pages
• 189 x 246 x 3mm | 113g
• United States
• English
• black & white illustrations
• 1236811763
• 9781236811769