sprocket.ps

%!ps-nonconforming
/inch {72 mul} bind def
/half {0.5 mul} bind def
/buffer 20 string def
/cot {dup cos exch sin div} bind def
/comment {pop} bind def
/fraction {div} bind def
/init {/Helvetica 10 selectfont
 currentpagedevice /PageSize get dup 1 get /pageheight exch def
 0 get /pagewidth exch def
 /fontheight {currentfont dup /FontBBox get dup 3 get % top
  exch 1 get sub % top - bottom
  exch /FontMatrix get 3 get mul} bind def % adjusted by height multiplier
 /lineheight {fontheight 1.2 mul} bind def % add 20% for line spacing
 /newline {0 lineheight neg rmoveto} bind def
} bind def
% chain info from http://www.gizmology.net/sprockets.htm
% pitch diameter is the diameter of the sprocket at the center of the rollers
% Pitch Diameter = P ÷ sin (180° ÷ N)
/pitchdiameter {(pitch teeth -) comment 180 exch div sin div} def
% outside diameter is the diameter of the sprocket at the ends of the teeth
% Outside Diameter = P × (0.6 + cot ( 180° ÷ N) )
/outerdiameter {(pitch teeth -) comment 180 exch div cot .6 add mul} def
/sprocket {(bore pitch rollerdiameter teeth -) comment
 /teeth exch def
 /rollerdiameter exch def
 /pitch exch def
 /bore exch def
 /pitchangle 360 teeth div def
 /rollerradius rollerdiameter half def
 /pitchradius pitch teeth pitchdiameter half def
 /outerradius pitch teeth outerdiameter half def
 gsave
 currentpoint translate newpath
 % remember rotation is in Cartesian space, so *counterclockwise*
 0.5 setgray
 gsave 0 0 pitchradius 0 360 arc closepath stroke grestore
 gsave 0 0 outerradius 0 360 arc closepath stroke grestore
 0 setgray % black for drilling and cutting
 gsave 0 0 bore half (radius) comment 0 360 arc closepath stroke grestore
 teeth {
  gsave
   0 pitchradius moveto currentpoint translate
   newpath pitchangle half neg rotate
   0 0 moveto
   % draw cross at centerpoint
   gsave 0 rollerradius half rlineto stroke grestore
   gsave 0 rollerradius half neg rlineto stroke grestore
   gsave rollerradius half 0 rlineto stroke grestore
   gsave rollerradius half neg 0 rlineto stroke grestore
   % circles for drilling base of teeth and for cutting the rest
   newpath  % necessary to prevent unwanted radius line
   0 0 rollerradius 180 pitchangle add 0 arc stroke
   0 0 pitch rollerradius sub 0 45 arc stroke
   0 0 pitch rollerradius sub 135 pitchangle add 180 pitchangle add arc stroke
  grestore pitchangle rotate
 } repeat
 grestore
} def
init
pagewidth 1 3 fraction mul pageheight 1 3 fraction mul moveto
5 16 fraction inch 1 2 fraction inch 5 16 fraction inch 5 sprocket
pagewidth 2 3 fraction mul pageheight 1 3 fraction mul moveto
5 16 fraction inch 1 2 fraction inch 5 16 fraction inch 6 sprocket
pagewidth 1 3 fraction mul pageheight 2 3 fraction mul moveto
5 16 fraction inch 1 2 fraction inch 5 16 fraction inch 7 sprocket
pagewidth 2 3 fraction mul pageheight 2 3 fraction mul moveto
5 16 fraction inch 1 2 fraction inch 5 16 fraction inch 8 sprocket
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