; === HELICAL MILLING ===

; Helix-mill a hole.
; Assumes metric, XY plane, feedrate, and tool compensation are set.
O<helix_mill> sub
  #<xcenter> = #1 ; [mm] X center
  #<ycenter> = #2 ; [mm] Y center
  #<radius>  = #3 ; [mm] Hole radius
  #<zstart>  = #4 ; [mm] Z start position
  #<zend>    = #5 ; [mm] Z end position

  G0 X[ #<xcenter> - #<radius> ] Y#<ycenter>

  G0 Z#<zstart>
  #<znow> = #<zstart>

  ; Mill out body with several full helical turns
  O100 while [ #<znow> GT [ #<zend> + #<_zstep> ] ]

    #<znow> = [ #<znow> - #<_zstep> ]
    G2 I#<radius> J0 Z#<znow>

  O100 endwhile

  G2 I#<radius> J0 Z#<zend>

  ; Flat out the bottom
  G2 I#<radius> J0

O<helix_mill> endsub

; === SCREW/NUT POCKETING ===

; Mill a pocket for a screw head.
; Assumes metric, XY plane, feedrate, and tool diameter are set.
O<screw_head_pocket> sub

  #<xcenter>     = #1 ; [mm] X center
  #<ycenter>     = #2 ; [mm] Y center
  #<head_radius> = #3 ; [mm] Screw head thickness
  #<head_depth>  = #4 ; [mm] Screw head depth

  ; Initial position
  G0 X#<xcenter> Y#<ycenter>

  ; Cutter compensation to the right.
  G42

  ; Make a pocket for screw head.
  #<rnow> = #<head_radius>
  O100 while [ #<rnow> GT [ #5410 / 2 ] ]

    O<helix_mill> call [#<xcenter>] [#<ycenter>] [#<rnow>] [0.] [-#<head_depth>]

    #<rnow> = [ #<rnow> - #5410 * 0.9 ] ; Subtract 90% tool diameter

    G0 Z0.0 ; Get tool up for another plunge

  O100 endwhile

  ; Cleanup.
  G40
  G0 Z#<_zsafe>

O<screw_head_pocket> endsub

; --- BEGIN CONFIGURATION ---

; Don't forget to set up tool table.

T2 M6 S2500 F300 ; 3.175mm cylindrical

#<_zsafe>       = 10.  ; [mm] Safe Z
#<_zstep>       = 3.   ; [mm] Z step

#<_thickness>   = 12.7 ; [mm] Sheet thickness
#<_head_radius> = 6.   ; [mm] Screw head radius
#<_head_depth>  = 8.   ; [mm] Screw head depth

; --- END CONFIGURATION ---

G21 G90 G17 ; Metric, Absolute, XY plane
M3

/O<screw_head_pocket> call [0]   [0]   [#<_head_radius>] [#<_head_depth>]
O<screw_head_pocket> call [0]   [130] [#<_head_radius>] [#<_head_depth>]
O<screw_head_pocket> call [0]   [260] [#<_head_radius>] [#<_head_depth>]
O<screw_head_pocket> call [150] [0]   [#<_head_radius>] [#<_head_depth>]
O<screw_head_pocket> call [150] [130] [#<_head_radius>] [#<_head_depth>]
/O<screw_head_pocket> call [150] [260] [#<_head_radius>] [#<_head_depth>]

G0 Z#<_zsafe>
M2