that cannot be centered accurately and all
glued-up work with rough corners should be run slowly until all corners
are taken off and the stock runs true. At high speed the centrificial
force on such pieces is very great, causing the lathe to vibrate, and
there is a possibility of the piece being thrown from the lathe thus
endangering the worker as well as those around him. After the stock is
running true the speed may be increased.

[Illustration: Fig. 1. - Wood Turning Lathe]

TO FIGURE THE DIAMETER OF PULLEYS

Suppose a motor runs 1500 R.P.M. and is fitted with a 4" pulley. Suppose
also, a main shaft should run 300 R.P.M.

Then, 1500 : 300 :: x : 4;
Or, 300x = 6000,
x = 20, or the diameter of the large pulley on the main shaft.

Suppose again that a line shaft runs 300 R.P.M., and a counter shaft 600
R.P.M. The counter shaft has a pulley 4" in diameter. The pulley on the
line shaft must then have a diameter of 8".

300 : 600 :: 4 : x;
Or, 300x = 2400,
x = 8"

Suppose the cone pulley on the counter shaft runs 600 R.P.M.; a lathe
spindle runs 2200 R.P.M., when connected with the small cone pulley
which has a diameter of 3". The large cone pulley has then a diameter of
11".

600 : 2200 :: 3 : x
Or, 600x = 6600;
x = 11"

RULES FOR FINDING THE SPEEDS AND SIZES OF PULLEYS

1. To find the diameter of the driving pulley:

Multiply the diameter of the driven by the number of revolutions it
should make and divide the product by the number of revolutions of the
driver. (20 x 300 = 6000; 6000 / 1500 = 4"--diameter of motor pulley.)

2. To find the diameter of the driven pulley:

Multiply the diameter of the driver by its number of revolutions and
divide the product by the number of revolutions of the driven. (4 x 1500
= 6000; 6000 / 300 = 20"--diameter of the driven pulley.)

3. To find the number of revolutions of the driven pulley:

Multiply the diameter of the driver by its number of revolutions and
divide by the diameter of the driven. (4 x 1500 = 6000; 6000 / 20 =
300--revolutions of driven pulley.)

POINTS ON SETTING UP LATHE AND SHAFTING

The counter shaft should be about 7' above the lathe. A distance of 6'
from the center of the shaft to the center of the spindle is sufficient.
In setting a lathe or hanging a counter shaft it is necessary that both
be level. The counter shaft must be parallel to the line shaft. When the
counter shaft is in position a p