Machinery Repairman

Screw Arbor
Figure 7-51.—Screw arbor.
Screw arbors (fig. 7-51) are used with cutters that
have threaded mounting holes. The threads may be
left- or right-hand.
Taper Adapter
Taper adapters are used to hold and drive
taper-shanked tools, such as drills, drill chucks,
reamers, and end mills. You insert the tool into the
tapered hole in the adapter. The code for a taper
adapter includes the number representing the standard
milling machine spindle taper and the number and
series of the internal taper. For example, the taper
adapter code number 43M means:
4 = taper identification number—40
3M = internal taper—number 3 Morse
If a letter is not included in the code number, the taper
is understood to be a Brown and Sharpe. For
example, 57 means:
5 = taper number—50
7 = internal taper—number 7 B and S
Figure 7-52.—Taper adapter.
7-29
and 50-10 means:
50 = taper identification number
10 = internal taper—number 10 B and S
Figure 7-52 shows a typical taper adapter. Some
cutter adapters are designed to be used with tools that
have taper shanks and a cam locking feature. The
cam lock adapter code indicates the number of the
external taper, number of the internal taper (which is
usually a standard milling machine spindle taper), and
the distance that the adapter extends from the spindle
of the machine. For example, 50-20-3 5/8 inches
means:
50 =
20 =
3 5/8 =
Cutter Adapter
taper identification number (external)
taper identification number (internal)
distance adapter extends from spindle is
3 5/8 inches
Cutter adapters, such as the one shown in figure
7-53, are similar to taper adapters except they always
have straight, rather than tapered, holes. They are
used to hold straight shank drills, end mills, and so
forth. The cutting tool is secured in the adapter by a
setscrew. The code number indicates the number of
the taper and the diameter of the hole. For example,
50-5/8 means the adapter has a number 50 taper and a
5/8-inch-diameter hole.
Figure 7-53.—Cutter adapter.