; how to use polar coordinates:  
; use the format @radius^angle in place of specifying X,Y words

G20 G90
G0 X0 Y0 Z0

; drill three bolt holes on a 5" diameter
G0 X2.5 Y0
G81 R.1 Z-0.5 F60
^120
^240

G90 @1 ^33
; drill a row of holes 1" apart along a 33 degree feature
G91 G81 @1 R.1 Z-0.5 L5

G90 G0 X2 Y0
; drill 17 evenly-spaced bolt holes on a 4" diameter
G91 G81 ^[360/17] R.1 Z-0.5 L17

M2