Instruction Manual Section Five
The relief on the end teeth of end mills should be about 3 degrees to 5 degrees.
On formed milling cutters or involute gear cutters, relief does not have to be
considered in resharpening because the teeth are so formed that when they are
ground radially on the face, the relief remains the same.
C. Determining the Relief Angle:
The relief angle is determined by the setting of the grinding wheel, the cutter
and the tooth rest. Either a straight wheel or a cup wheel may be used. If
the lands on the cutter teeth are narrow, a straight wheel is frequently used.
If the lands are wide, a cup wheel should be used. See Figure 14. It is possible
to use a straight wheel on wide lands by swiveling the wheel head about 1
degree from the zero line so that the cut approaches a straight line.
Figure 14—Showing effect of wheel shape on relief angle.
The general procedure in determining the setting for the relief angle is to
bring the center of the wheel and the work, as well as the end of the toothrest
blade, all on the same plane, and then to raise or lower the Wheelhead the
proper distance to give the desired relief angle. When a straight wheel is used,
this distance varies with the diameter of the wheel. When a cup wheel is used,
the distance varies with the diameter of the cutter.
On the B6060 and B6052 series cutter grinding machines, the tilting Wheelhead
unit is provided with a dial graduated in degrees for quickly setting the angle
of a cup wheel face to the exact relief angle desired. With this feature, when
a cup wheel is used, it is not necessary to go through the procedure of bringing
the center of the wheel and the work onto exactly the same horizontal plane.
After tilting the Wheelhead to the desired degree, simply adjust the toothrest
to the same height as the center of the work (BY MICROMETER, OR SMALL
MOVEMENT OF WHEELHEAD). The toothrest may be located on the wheel-
head or the table, depending on the nature of the setup. If this tilting feature
is not available, the toothrest setting for the relief angle must be obtained either
from the tables, pages 104-108, or by the following methods and calculations.
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