Table 61.-WORK DONE BY PLANING, SHAPING, SLOTTING, DRILLING, AND BORING MACHINES AND LATHES. ft. in. Hrs. Min. Ditto Slot drilling keyway, 6 inches long × × inch Planing keyway, 4 feet long x inch wide x inch deep ditto 9 ditto XIX I inch Screwing machine, screwing inch iron, I foot long Screwing I inch iron, I foot long I Tapping 1 gross inch nuts Tapping I gross I inch nnts Drilling 1 inch diameter holes in cast-iron, per square foot I NOTE.-The time given includes the tirae occupied in setting the work. cutting at one and the same time. Boring 6 inch diameter holes in cast iron, per square foot Ditto 14 Ditto Ditto ditto ditto 23 18 Ditto ditto ditto 12 Turning I foot in length of round steel, 2 inch diameter Turning pulleys from 2 to 4 feet diameter, per square foot Turning fly-wheels from 7 to 12 ft.diameter, per square foot The lathes for turning pulleys and fly-wheels had several tools Table 63.-SPEED AND APPROXIMATE INDICATED HORSE-POWER REQUIRED TO DRIVE WOOD-WORKING MACHINERY, WITH AN AVERAGE Rate of Feed. Description of Wood-Working Machinery. Circular saw bench. Size of saw, 14 in. diameter 1500 6 Band saw. Diameter of saw pulleys, 24 inches 500 Ditto ditto 30 "" 450 46 Vertical timber frame to saw 12 in. logs. Speed of crank shaft Boring, chamfering, and shaping machine. Speed Rate of feed for planing and moulding machine, 20 to 30 feet per minute. Angle of plane and moulding irons, 25° for soft wood: 35° for hard wood. Breaking strain of band saws = 176 lbs. for each inch width of blade. Table 64.--SPEED OF GRINDSTONES FOR GRINDING TOOLS, &c. SPEED AND PROPORTIONS OF FANS. Speed of fan for smithy fires 185, and for a cupola 270 feet per second of circumference. Length of neck of spindle = 4 times the diameter of the spindle. To find the horse-power required for a fan.-Rule: Divide the square of the velocity of the tips of fan in feet per second by 1000, and multiply the result by the density of the blast in ounces per inch, which product multiply by the area of discharge at the tuyeres in square inches, and divide the result by 963. To find the density of fan blast in ounces per inch.-Rule: Divide the velocity in feet per second of the circumference by 4, square the result, and next divide by the product of the diameter of fan in feet by 120. WHEEL CUTTING. The Dividing Wheel on the mandrel of a wheel-cutting machine, is a worm-wheel, having usually 180 teeth; the change-wheel on the end of the worm-shaft is called the tangent-wheel, which is geared with an intermediate wheel or wheels, to the wheel on the end of the division-plate shaft. When convenient, the tangent-wheel should have the same number of teeth as that of the wheel to be cut, and the wheel on the division-plate shaft should have half the number of that of the dividing wheel, then two turns of the handle if the worm has a single thread, and one turn if it has a double thread, will give the required number of teeth to be cut. When this arrangement is not convenient, the change wheels may be found thus. Find the ratio between the number of teeth in the wheel to be cut, and that of the dividing wheel, which may be divided by any suitable number, when the numerator will represent the driver or division-plate wheel, and the denominator the driven or tangent-wheel. Thus, to cut a wheel with 180 dividing wheel ÷ 2 90 teeth 90 wheel to be cut ÷ 2 the wheels required, with one turn of the handle if a single-thread worm, or with half a turn if the worm has a double-thread. Table 65.-TABLE OF CHANGE WHEELS FOR A WHEEL-CUtting Teeth of Teeth to be Cut. to be Shaft. Shaft. Cut. Number Number Wheel Tangent Number Number Wheel Tangent Number Number Wheel Tangent of of on Wheel of on Wheel of of on Wheel Turns Division on Turns Division on Teeth Turns Division on of the Plate Worm of the Plate Worm Handle. Handle. Shaft. Shaft. to be of the Plate Worm Handle. Shaft. Shaft. of of Teeth to be Teeta Cut. of the Plate Worm Handle. Shaft. Shaft. to be Cut. Table 65 continued.-TABLE OF CHANGE WHeels. Οι Number Number Wheel Tangent Number Number Wheel Tangent Number Number Wheel Tangent of on Wheel of on Wheel Wheel Turns Division on Turns Division on Turns Division] on of the Plate Worm of the Plate Worm Handle. Shaft. Shaft. Handle. Shaft. Shaft. of of Teeth Cut. Rule to prove the correctness of change wheels for the above wheelcutting machine :— Divide the number of teeth in the wheel on the division-plate shaft, by the number of teeth in the wheel on the worm-shaft; multiply the quotient by the number of turns of the handle, and the product will be equal to the quotient of the number of teeth in the dividing wheel divided by the number. of teeth in the wheel to be cut. SCREW-CUTTING. A Single Train of change wheels for screw-cutting consists of 3 wheels :viz., I wheel on the lathe-spindle, called the driver; I wheel on the lathe's leading screw called the driven wheel, and one intermediate wheel to connect these two wheels, called the stud-wheel. In a double train, 4 wheels are used: a stud-pinion gearing into the leading screw-wheel, |