| Corner rounding endmills are form cutters and should be treated
as such when calculating speeds and feeds. Looking at figure 1, you
will notice that the cutter is designed to form a full quadrant of
90 degrees of a circle. |
Figure 1. Corner Rounding Endmill
|
| Notice in the drawing in figure 2 that the cutter extends beyond
the tangent points of the arc. This produces two small flats. These
flats are important because they are reference surfaces for
determining the final cut. |
Figure 2. Reference edges on corner rounding
endmills.
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The corner radius that you machine with high-speed steel form
cutters should be done with two passes. On the first pass, adjust
the cutter so that the two reference or straight edges are 0.02 to
0.03 inches away from the corner surfaces to be machined. Use layout
dye to mark the area to be machined. On the second or final pass,
adjust the cutter so that the two reference edges just brush the
bluing. If you have done the cutting correctly, the radius produced
should be smooth and blended at the tangency points.
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