Machinery's Handbook, 31st Edition
904 Cutter Grinding Indicator Drop Method of Checking Relief and Rake Angles.— The most convenient and inexpensive method of checking the relief and rake angles on milling cutters is by the indicator drop method. Three tables, Table 1, Table 3 and Table 4, of indicator drops are provided in this section for checking radial relief angles on the peripheral teeth, relief angles on side and end teeth, and rake angles on the tooth faces.
A
R
W
Section A–A
H
A
Fig. 1. Setup for Grinding Eccentric-Type Radial Relief Angle Table 3. Indicator Drops for Checking Relief Angles on Side Teeth and End Teeth
Given Relief Angle
Checking Distance, Inch
1 °
2 °
3 °
4 °
5 °
6 °
7 °
8 °
9 °
Indicator Drop, inch
.005 .010 .015 .031 .047 .062
.00009 .00017 .00026 .00035 .0004 .0005 .0006 .0007 .0008 .00017 .00035 .00052 .0007 .0009 .0011 .0012 .0014 .0016 .00026 .0005 .00079 .0010 .0013 .0016 .0018 .0021 .0024 .00054 .0011 .0016 .0022 .0027 .0033 .0038 .0044 .0049 .00082 .0016 .0025 .0033 .0041 .0049 .0058 .0066 .0074 .00108 .0022 .0032 .0043 .0054 .0065 .0076 .0087 .0098
“Radial” Starting Position
Indicator Drop
Checking Distance
Fig. 2. Setup for Checking the Radial Relief Angle by Indicator Drop Method The setup for checking the radial relief angle is illustrated in Fig. 2. Two dial test indica tors are required, one of which should have a sharp-pointed contact point. This indicator is positioned so that the axis of its spindle is vertical, passing through the axis of the cutter. The cutter may be held by its shank in the spindle of a tool and cutter grinder workhead, or
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