anywhere on the overarm. Small arbor supports give additional clearance
below the arbor supports when small diameter cutters are being used. Small
arbor supports can provide support only at the extreme end of the arbor, for
this reason they are not recommended for general use. Large arbor supports
can be positioned at any point on the arbor. Therefore they can provide
support near the cutter, if necessary. The large arbor support should be
positioned as close to the cutter as possible, to provide a rigid tooling
setup. Although arbor supports are not classified, a general rule of thumb
can be used for arbor selection--the old reference type A is of a small
bearing diameter, and the old reference type B is of a large bearing
diameter.