(info: Counter Bore a drilled hole)
(assumptions = material top is Z0, tool is loaded and offsets set)
(hole diameter > tool diameter, material to be removed is less than tool diameter)
o<cb> sub
  #<x-center>     = #1 (X Center)
  #<y-center>     = #2 (Y Center)
  #<hole-dia>     = #3 (Counter Bore Diameter)
  #<hole-depth>   = #4 (Counter Bore Depth)
  #<cut-depth>    = #5 (Depth Per Helix)
  #<tool-dia>     = #6 (Tool Diameter)
  #<safe-z>       = #7 (Safe Z Height)
  #<feed>         = #8 (Feed Rate)
  #<rpm>          = #9 (Spindle RPM)
  #<coolant>      =#10 (Coolant)

  #<x-offset> = [[#<hole-dia> - #<tool-dia>]/2]
  #<x-start>  = [#<x-center> - #<x-offset>]
  G0 X#<x-center> Y#<y-center> Z#<safe-z>
  M3 S#<rpm> M#<coolant>
  G1 X#<x-start> F#<feed>
  G2 X#<x-start> I#<x-offset> Z0 P1
  ; cut counterbore
  o<100> while [#5422 GT -#<hole-depth>]
    o<110> if [-#<hole-depth> LT [#5422 - #<cut-depth>]]
      G2 X#<x-start> I#<x-offset> Z[#5422 - #<cut-depth>] P1
    o<110> else
      G2 X#<x-start> I#<x-offset> Z-#<hole-depth> P1
    o<110> endif
  o<100> endwhile
  G2 X#<x-start> I#<x-offset>
  G1 X#<x-center> Y#<y-center>
  G0 Z#<safe-z>
  M5 M9
o<cb> endsub