speed stock up to 3" in diameter can be turned with safety. Stock from
3" to 6" in diameter should be turned on the second or third step, and
all stock over 6" on the last step. The speed at which a lathe should
run depends entirely upon the nature of the work to be done and the kind
of material used. Pieces 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;