Table 61.-WORK DONE BY PLANING, SHAPING, SLOTTING, DRILLING, AND BORING MACHINES AND LATHES.

Description of Work.

Time required
for 2 Cuts, viz.,
I Roughing
and 1 Finishing
Cut, to Finish
1 Square Foot.

Description of Work.

Boring 6 inch diameter holes in cast iron, per square foot
Turning I ft. length of wrought iron shaft, I in. diameter

Ditto

ditto

35

Ditto

ditto

332221

Ditto

ditto

I

Ditto
ditto
ditto 9
XIX I inch
Planing keyway, 4 feet long x inch wide x inch deep
Screwing machine, screwing inch iron, I foot long
Screwing I inch iron, I foot long

I

I

Drilling I inch diameter holes in cast-iron, per square foot

I

I

30

Ditto

ditto

Ditto

ditto

Ditto

ditto

Turning I foot in length of round steel, 2 inch diameter
Turning I foot in length of round brass, 2 inch diameter.
Surfacing a flat cast-iron plate, per square foot
Surfacing a flat wrought-iron plate, per square foot
Surfacing a flat steel plate, per square foot
Surfacing a flat brass plate, per square foot
Turning pulleys from 2 to 4 feet diameter, per square foot
Turning pulleys from 5 to 8 feet diameter, per square foot
Turning small fly-wheels from 3 to 6 feet diameter, per
square foot

Turning fly-wheels from 7 to 12 ft. diameter, per square foot
Turning hard cast iron rolls, per square foot

NOTE.-The time given includes the time occupied in setting the work.

O

100

ditto

ditto

12

Table 63.-SPEED AND HORSE-Power required TO DRIVE WOOD-WORKING

MACHINERY.

Description of Machinery.

Circular saw bench. Size of saw, 14 in. diameter

ditto 24

Ditto

23456

3

Band saws.

Diameter of saw pulleys, 24 inches

400

Vertical timber frame to saw 12 in. logs. Speed of

ditto

Boring, chamfering, and shaping machine. Speed
Planing and moulding machine

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.

Diameter of the grindstone, in

inches

Number of revolutions of the stone per minute

24 30 36 42 48 5460 66 72 78 84 9096

130 106 88 75 66 58 52 48 44 40 37 35 33

SPEED AND PROPORTIONS OF FANS.

Speed of fan for smithy fires 185, and for a cupola 270 feet per second of circumference.

Fan blades = diameter of fan each way.

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 23 the wheels required, with one turn 90 wheel to be cut ÷ 2

=

of the handle if a single-thread worm, or with half a turn if the worm has a double-thread.

of

on

Teeth

to be

of the Plate

Worm

Cut.

Handle.

Shaft.

Shaft.

to be
Cut.

Table 65.-TABLE OF CHANGE WHEELS FOR A WHEEL-CUTTING
MACHINE HAVING A DIVIDING WHEEL WITH 180 Teeth.

Number Number Wheel Tangent Number Number Wheel Tangent Number Number Wheel Tangent of of on Wheel of on Wheel of of on Wheel Teeth Turns Division Turns Division' on Teeth Turns Division on of the Plate Worm to be Handle.

Shaft.

Shaft.

Cut.

of the Plate Worm Handle. Shaft. Shaft.

of

Teeth to be

Cut.

Table 65 continued.-TABLE OF CHANGE Wheels.

Number Number Wheel Tangent Number Number Wheel Tangent Number Number Wheel Tangent of on Wheel of of on Wheel of of on Wheel Turns Division on Teeta Turns Division on Turns Division on of the Plate Worm to be of the Plate Worm Handle. Shaft. Shaft. Cut. Handle.

Teeth

to be

Shaft.

Shaft.

Cut.

of the Plate Worm Handle. Shaft.

Shaft.

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; 1 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,