"A COURSE IN WOOD TURNING"
By ARCHIE S. MILTON,OTTO K. WOHLERS
CONTENTS
CHAPTER I.- Introduction
CHAPTER II. - The Lathe
CHAPTER III. - Wood Turning Tools
CHAPTER IV. - Spindle Turning
CHAPTER V. - Tool Processes in Spindle Turning
CHAPTER VI.- Oval Turning
CHAPTER VII. - Duplicate Turning
CHAPTER VIII - Finishing and Polishing
CHAPTER IX - Face-Plate and Chuck Turning
CHAPTER X - Tool Processes in Face-Plate and Chuck Turning
CHAPTER XI - Spiral Turning
THE LATHE
The sizes of turning lathes are given as 10", 12", etc. These figures
denote the diameter, or size, of the largest piece of work that can be
turned on them. The measurement is taken from the center point of the
live center to the bed of the lathe (usually 5" or 6") and is one-half
the diameter of the entire circle. The length of a lathe is determined
by the length of a piece of work that can be turned. This measurement is
taken from the points of the live and dead centers when the tail stock
is drawn back the full extent of the lathe bed. Fig. 1 shows a turning
lathe with sixteen principal parts named. The student should learn the
names of these parts and familiarize himself with the particular
function of each.
CARE OF THE LATHE
The lathe should be oiled every day before starting. At the end of the
period the lathe should be brushed clean of all chips and shavings,
after which it should be rubbed off with a piece of waste or cloth to
remove all surplus oil. All tools should be wiped clean and put in their
proper places. If a student finds that his lathe is not running as it
should, he should first call the attention of the instructor to that
fact before attempting to adjust it; and then only such adjustments
should be made as the instructor directs.
SPEED OF THE LATHE
The speed of the lathe should range from 2400 to 3000 revolutions per
minute when the belt is on the smallest step of the cone pulley. At this
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.
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 plumb bob should be hung from the counter
shaft cone to the spindle cone; the lathe should be adjusted so that the
belt will track between the two cone pulleys. The axis of the lathe must
be parallel to that of the counter shaft. The lathe, however, need not
be directly beneath the counter shaft as the belt will run on an angle
as well as perpendicular.
