machine spindle taper of 3 1/2 inches per foot. The
largest diameter of the taper is identified by a number.
For example, the large diameter of a No. 40 milling
machine spindle taper is 1 3/4 inches. The following
numbers represent common milling machine spindle
tapers and their sizes:
1 3/4 inches
Figure 7-46.--Cutter diameter selection.
2 3/4 inches
4 1/4 inches
Standard arbors are available in styles A and B, as
You can mount milling machine cutters on several
bearing usually 1 1/32 inch in diameter. Style B arbors
types of holding devices. You must know the devices
have a sleeve-type outboard bearing. Numerals
and the purpose of each of them to make the most
identify the outside diameter of the bearing sleeves, as
suitable tooling setup for the operation. We will cover
the various types of arbors and the mounting and
dismounting of arbors in this section.
NOTE: Technically, an arbor is a shaft on which
1 7/8 inches
a cutter is mounted. For convenience, since there are
2 1/8 inches
so few types of cutter holders that are not arbors, we
will refer to all types of cutter holding devices as
2 3/4 inches
The inside diameter can be any one of several
standard diameters that are used for the arbor shaft.
Style A arbors sometimes have a sleeve bearing
There are several types of milling machine arbors.
that permits the arbor to be used as either a style A or
a style B arbor. A code system, consisting of
to hold and drive cutters that have mounting holes.
numerals and a letter, identifies the size and style of
One end of the arbor usually has a standard milling
the arbor. The code number is stamped into the flange
Figure 7-47.--Standard milling machine arbors.