解：选用T1=ф20铣刀、T2=中心钻、T3=ф6中心钻。

　
O001

G17 G40 G80

N001 G00 G91 G30 X0 Y0 Z0 T1;

M06;

G00 G90 G54 X0 Y0 Z0;

G43 H01 Z20 M13 S1000;

Z-42.;

G01 G42 D01 X-50. F400;

G02 I50.J0.F150;

G00 Y0.;

G40 Z100.;

G00 G90 G54 X-110. Y-100.;

Z-42.;

G01 G41 X-90. F500;

Y82

X-82. Y90.;

X82.;

X82. Y90.;

X-82.;

X82. Y-90.;

X-82.;

G00 Z100.;

G40;

N002 G00 G91 G30 X0 Y0 Z0 T1;

M06;

G00 G90 G54 X-60. Y-60.;

G43 H02 Z10 M03 S2000;

G99 G81 Z-3. R5. F150;

Y60.;

X60.;

Y-60.;

GOO G80 Z100.;

N003 G91 G30 X0 Y0 Z0 T3;

M6;

G00 G90 G54 X-60. Y-60.;

G43 H02 Z10 M03 S2000;

G99 G81 Z-12 R3. F150;

Y60.;

X60. Z-42.;

Y-60.;

GOO G80 Z100.;

G00 G28 Y0;

M30;