Therefore, to turn a taper, you must either mount the
pertinent measurements in appropriate tables found in
work in the lathe so the axis on which it turns is at an
the current edition of the Machinery's Handbook.
angle to the axis of the lathe, or cause the cutting tool
There are three standard tapers with which you
to move at an angle to the axis of the lathe.
should be familiar: (1) the MORSE TAPER
There are three methods in common use for
(approximately 5/8 inch per foot) used for the tapered
holes in lathe and drill press spindles and the
attachments that fit them, such as lathe centers, drill
SET OVER THE TAILSTOCK, which
shanks, and so on; (2) the BROWN & SHARPE
moves the dead center away from the axis of
TAPER (1/2 inch per foot, except No. 10, which is
the lathe and causes work supported between
0.5161 inch per foot) used for milling machine
centers to be at an angle with the axis of the
spindle shanks; and (3) the JARNO TAPER (0.600
inch per foot) used by some manufacturers because of
the ease with which its dimensions can be determined:
USE THE COMPOUND REST set at an
angle, which causes the cutting tool to be fed at
the desired angle to the axis of the lathe.
Diameter of large end =
USE THE TAPER ATTACHMENT, which
also causes the cutting tool to move at an angle
to the axis of the lathe.
Diameter of small end =
In the first method, the cutting tool is fed by the
longitudinal feed parallel to the lathe axis, but a taper
is produced because the work axis is at an angle. In
Length of taper =
the second and third methods, the work axis coincides
with the lathe axis, but a taper is produced because the
Two additional tapers that are considered standard
cutting tool moves at an angle.
are the tapered pin and pipe thread tapers. Tapered
SETTING OVER the TAILSTOCK.--As stated
pins have a taper of 1/4 inch per foot, while tapered
earlier in this chapter, you can move the tailstock top
pipe threads have a taper of 3/4 inch per foot.
sideways on its base by using the adjusting screws. In
straight turning you use these adjusting screws to
Methods of Turning Tapers
align the dead center with the tail center by moving
the tailstock to bring it on the center line of the spindle
In ordinary straight turning, the cutting tool
axis. For taper turning, you deliberately move the
moves along a line parallel to the axis of the work,
tailstock off center, and the amount you move it
causing the finished job to be the same diameter
determines the taper produced. You can approximate
throughout. If, however, in cutting, the tool moves at an
the amount of setover by using the zero lines
angle to the axis of the work, a taper will be produced.
inscribed on the base and top of the tailstock as shown
indicator to measure the distance you move the
In turning a taper by this method, the distance
between centers is of utmost importance. To
illustrate, figure 6-77 shows two very different tapers
Figure 6-77.--Setover of tailstock showing importance of
considering length of work.
Figure 6-76.--Tailstock setover lines for taper turning.