Modern Machinery Volume 24, No. 12 (Paperback)

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. 1910 edition. Excerpt: ...in a lathe of which the guide screw thread is J4 inch pitch. If a wheel of 55 teeth is placed on the mandrel, what wheel must be placed on the guide screw to cut the abovementioned thread; also what other pair of wheels may be used alternately if necessary? In a problem of this kind all that is necessary is to find the ratio or proportion existing between the pitch of the guide screw and the pitch required. It will be seen that the decimal equivalent of 516 equals.3125 and the decimal equivalent of Yi equals.5. Therefore, set 3,125 on A to 5 on B, and read over 55 on A 88 on B as the required number of teeth for the wheel on the lead screw. With the slide set at the above ratio anv other pair of wheels which will produce the same results may be found simplv by moving the runner back and forth such as we find 15 25 90 would suffice. 24 40 144 Multiplication and Division. The ordinary arithmetical processes are performed on this rule in exactly the same way that they are on the Mannheim rule. As an example of multiplication, suppose it is required to multiply 3.7 by 1.9. The 1 on the left hand end of the C scale is placed opposite the 3.7 on the D scale. The product 7.03 is then read on the D opposite 1.9 on the C scale. Division is the exact reverse of multiplication. Thus to divide 7.03 by 1.9, we place 1.9 on the C scale opposite 7.03 on the D scale and read the the A scale directly above 3 on the D scale and 3, the square root of 9, appears on the D scale directly below 9 on the A scale. Cubes and Cube-roots. As an example of finding the cube of a given number let us proceed to find the cub6 of 3. Place the index of the C scale opposite 3 on the D scale. Then read 27, the cube of 3, on the A scale opposite 3 on the B scale. To find the...