Initial

6 files changed, 683 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c25a6bd
--- a/dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/Makefile.local
+/*.stl
+/*.gcode
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..9444a03
--- a/dev/null
+++ b/Makefile
@@ -0,0 +1,22 @@
+-include Makefile.local
+
+OPENSCAD_APP?=/Applications/OpenSCAD.app
+OPENSCAD_BIN?=${OPENSCAD_APP}/Contents/MacOS/OpenSCAD
+OPENSCAD_FLAGS=-D draft=false
+
+default:
+        @echo "And?"
+
+clean:
+        rm -f *.stl *.gcode
+
+stl-another-%:
+        $(MAKE) another-$*-{body,lever}.stl
+
+another-%-body.stl: another-%.scad another.scad
+        $(OPENSCAD_BIN) $(OPENSCAD_FLAGS) -D 'what="body"' -o "$@" "$<"
+another-%-lever.stl: another-%.scad another.scad
+        $(OPENSCAD_BIN) $(OPENSCAD_FLAGS) -D 'what="lever"' -o "$@" "$<"
+
+%.stl: %.scad
+        ${OPENSCAD_BIN} ${OPENSCAD_FLAGS} -o "$@" "$<"
diff --git a/another-E0.scad b/another-E0.scad
new file mode 100644
index 0000000..2f639b9
--- a/dev/null
+++ b/another-E0.scad
@@ -0,0 +1,13 @@
+use <another.scad>;
+
+what="body";
+vitamins=false;
+
+rotate([180,0,0])
+the_extruder(what=what, vitamins=vitamins,
+
+ left=true,
+ pulley_d=12.65, pulley_elevation=1,
+ teeth_elevation = 7.88,
+ bore_l = 20
+);
diff --git a/another-E1.scad b/another-E1.scad
new file mode 100644
index 0000000..bbd42f0
--- a/dev/null
+++ b/another-E1.scad
@@ -0,0 +1,13 @@
+use <another.scad>;
+
+what="body";
+vitamins=false;
+
+rotate([180,0,0])
+the_extruder(what=what, vitamins=vitamins,
+
+ left=false,
+ pulley_d=11.5, pulley_elevation=1,
+ teeth_elevation=7.5,
+ bore_l=17.6
+);
diff --git a/another.scad b/another.scad
new file mode 100644
index 0000000..f78d1b0
--- a/dev/null
+++ b/another.scad
@@ -0,0 +1,300 @@
+draft=true;
+layer_height=0.2; extrusion_width=0.4;
+epsilon=0.01;
+$fs=0.0125;
+
+use <threads.scad>;
+module pushfit_thread(h=10) {
+ thr = 3/8 + .5/25.4;
+ slit = 25.4*thr/2 + 0.4;
+ if(draft) cylinder(d=thr*25.4,h=h);
+ else english_thread(diameter=thr,threads_per_inch=28,length=h/25.4,internal=true);
+ translate([-2,-slit,0]) cube([4,2*slit,h]);
+}
+
+module the_extruder(
+ // motor properties
+ gearbox_d = 36,
+         mount_d = 28,                          // the distance between opposite mounting holes
+ mounthole_depth = 5,
+         protrusion_d = 22, protrusion_h = 2.2,         // the dimensions of the protrusion on top of gearbox
+ bore_d = 8, bore_l = 17.6,
+ // pulley properties
+ pulley_d = 11.5, pulley_h=10,
+         pulley_elevation = 1,                  // pulley elevation above the protrusion
+         teeth_elevation = 7.5,                         // distance from the bottom of the pulley to its teeth
+ // idler properties
+         idler_d = 9.5, idler_h = 4, idler_id = 3,// idler dimensions: outer and inner diameters and height
+ // spring properties
+         spring_d = 10, spring_lc = 9.6,        // spring diameter and compressed length
+ // filament path properties
+ filament_d = 1.75,
+ filament_path_d = 2,
+         filament_guide_d = 4,                  // PTFE filament guide diameter
+
+ // screw it
+ mount_screw_d = 3, mount_screw_l = 20,
+ mount_screwhead_d=6, mount_screwhead_h=3,
+
+ // empty spaces
+         idler_travel = 3,                      // how far should idler travel when pressed
+ idler_clearance=1,
+ pulley_clearance=2,
+         lever_v_clearance=.7,                  // vertical clearance for the lever
+ spring_d_clearance=1,
+         protrusion_tolerance_h=.5,             // horizontal tolerance for the motor protrusion
+         protrusion_tolerance_v=.5,             // vertical tolerance for the motor protrusion
+ mount_screw_d_tolerance=.5,
+ idler_v_tolerance=.5,
+
+ what="lever",
+ left=false,
+ vitamins = true
+) {
+ lever_shell = mount_screwhead_h+0.5;
+ lever_thickness=max(spring_d+layer_height*8,idler_h+idler_v_tolerance+2*lever_shell);
+ lsd = idler_d-idler_clearance*2;
+ longwing=gearbox_d/2+spring_d/2+lsd/2;
+ h_ = (pulley_d+idler_d)/(2*sqrt(2));
+ ri = sqrt( pow(h_,2) + pow(mount_d/2-h_,2) );
+ spring_dl = idler_travel*longwing/ri;
+
+ module mirrorleft() {
+  mirror([left?0:1,0,0]) children();
+ }
+ module place_idler() {
+  rotate([0,0,45])
+  translate([(pulley_d+idler_d)/2,0,0])
+  children();
+ }
+ module finger_indent(d=lever_thickness,depth/*=1*/,r/*=15*/) {
+  if(depth) {
+   hh = (-4*pow(depth,2)+pow(d,2))/(8*depth);
+   rr = depth+hh;
+   translate([0,0,hh]) sphere(r=rr,$fn=2*PI*rr);
+  }else if(r) {
+   hh=sqrt(pow(r,2)-pow(d,2)/4);
+   translate([0,0,hh]) sphere(r=r,$fn=2*PI*r);
+  }
+ }
+
+ // vitamins
+ % if(vitamins) mirrorleft() {
+  translate([0,0,-epsilon]) mirror([0,0,1]) cylinder(d=gearbox_d,h=1,$fn=60);
+  for(zr=[0:90:359]) rotate([0,0,zr]) translate([mount_d/2,0,0])
+   cylinder(d=mount_screw_d,h=20,$fn=30);
+  translate([0,0,-epsilon]) cylinder(d=protrusion_d,h=protrusion_h,$fn=30);
+  translate([0,0,protrusion_h]) {
+   cylinder(d=bore_d,h=bore_l,$fn=30);
+   translate([0,0,pulley_elevation]) {
+    cylinder(d=pulley_d,h=pulley_h,$fn=30);
+    translate([0,0,teeth_elevation]) {
+     place_idler() {
+      cylinder(d=idler_d,h=idler_h,center=true,$fn=30);
+      cylinder(d=idler_id,h=lever_thickness+2,center=true,$fn=30);
+     }//place idler
+     // filament path
+     rotate([0,0,45]) translate([(pulley_d-filament_path_d)/2,0,0]) {
+      rotate([90,0,0]) cylinder(d=filament_d,h=gearbox_d*2,center=true,$fn=15);
+      rotate([-90,0,0])
+      translate([0,0,mount_d/sqrt(2)/2+mount_screw_d])
+      pushfit_thread();
+     }
+    }//translate teeth
+   }//translate pulley
+  }//translate protrusion
+ }// vitamins to let
+
+ module lever() {
+  translate([0,0,protrusion_h+pulley_elevation+teeth_elevation]) {
+   difference() {
+    union() {
+     hull() {
+      place_idler()
+      cylinder(d=lsd,h=lever_thickness,center=true,$fn=60);
+      translate([mount_d/2,0,0])
+      cylinder(d=lsd,h=lever_thickness,center=true,$fn=60);
+     }//hull
+     hull() {
+      translate([mount_d/2,0,0])
+      cylinder(d=lsd,h=lever_thickness,center=true,$fn=60);
+      translate([mount_d/2,-longwing,0]) rotate([0,90,0])
+      cylinder(d=lever_thickness,h=lsd,center=true,$fn=60);
+     }//hull
+    }//union
+ 
+    // filament path
+    place_idler() translate([-(idler_d+filament_path_d)/2,0,0]) rotate([90,0,0]) {
+     cylinder(d=filament_path_d,h=3*gearbox_d,center=true,$fn=30);
+     translate([0,-filament_path_d/2/sqrt(2),0]) rotate([0,0,45])
+     cube(size=[filament_path_d/2,filament_path_d/2,3*gearbox_d],center=true);
+    }
+    
+    // idler space and mounting hole
+    place_idler() {
+     difference() {
+      cylinder(d=idler_d+idler_clearance*2,h=idler_h+idler_v_tolerance,center=true,$fn=60);
+      // supports
+      for(y=[-lsd/2+extrusion_width:(lsd-2*extrusion_width)/3:lsd/2-extrusion_width])
+       translate([-lsd/2-1,y-extrusion_width/2,-idler_h/2-idler_v_tolerance/2-1])
+       cube(size=[lsd+2,extrusion_width,idler_h+idler_v_tolerance+2]);
+     }
+     cylinder(d=mount_screw_d+mount_screw_d_tolerance,h=lever_thickness+2,center=true,$fn=30);
+     translate([0,0,lever_thickness/2-mount_screwhead_h]) 
+     cylinder(d=mount_screwhead_d,h=mount_screwhead_h+1,$fn=2*PI*mount_screwhead_d);
+    }
+    // mounting screw hole
+    translate([mount_d/2,0,0])
+    cylinder(d=mount_screw_d+mount_screw_d_tolerance,h=lever_thickness+2,center=true,$fn=2*PI*mount_screw_d);
+    
+    // lever end
+    translate([mount_d/2,0,0]) rotate([0,90,0]) {
+     translate([0,-longwing,lsd/2]) finger_indent(d=lever_thickness-1,r=15);
+     translate([0,-longwing,0])
+     mirror([0,0,1])
+     difference() {
+      cylinder(d=spring_d+spring_d_clearance,h=lsd,$fn=2*PI*spring_d);
+      sphere(d=spring_d*3/4,$fn=PI*spring_d);
+     }
+    }//rotate-translate
+   }//difference
+   // bridging patch
+   place_idler()
+   translate([0,0,lever_thickness/2-mount_screwhead_h])
+   mirror([0,0,1])
+   cylinder(d=mount_screwhead_d,h=layer_height);
+  }//translate
+ }//lever module
+ 
+ module body() {
+  filament_elevation=protrusion_h+pulley_elevation+teeth_elevation;
+  ls_z = filament_elevation;
+  body_h = max(protrusion_h+bore_l,mount_screw_l-mounthole_depth/2+mount_screwhead_h,ls_z*2);
+  ls_h = lever_thickness+lever_v_clearance;
+  difference() {
+   union() {
+   cylinder(d=gearbox_d,h=body_h,$fn=2*PI*gearbox_d);
+    // finger and spring support
+    fsw = gearbox_d/2+mount_screwhead_d/2;
+    translate([-gearbox_d/2,0,0]) difference() {
+     union() {
+      hull() {
+       translate([0,-longwing,ls_z])
+       rotate([0,90,0])
+       cylinder(d=lever_thickness,h=fsw,$fn=2*PI*lever_thickness);
+       hh=body_h-ls_z;
+       translate([0,0,ls_z-lever_thickness/2])
+       mirror([0,1,0]) cube(size=[fsw,longwing-hh+lever_thickness/sqrt(2),hh+lever_thickness/2]);
+       hhh=ls_z;
+       translate([0,0,0])
+       mirror([0,1,0]) cube(size=[fsw,longwing-hhh+lever_thickness/sqrt(2),hhh+lever_thickness/2]);
+      }
+     }
+     translate([0,-longwing,ls_z]) rotate([0,-90,0])
+     finger_indent(d=lever_thickness-1,r=15);
+    } // translate
+    
+    // pushfit bracket
+    translate([0,0,filament_elevation])
+    rotate([0,0,45]) translate([pulley_d/2,0,0])
+    rotate([-90,0,0])
+    translate([0,0,mount_d/sqrt(2)/2+mount_screw_d-gearbox_d/2/*TODO:*/])
+    cylinder(r=min(body_h-filament_elevation,filament_elevation)/sin(60)-epsilon,h=10+gearbox_d/2/*TODO:*/,$fn=6);
+   }//union (first child of difference)
+   // protrusion
+   translate([0,0,-1])
+   cylinder(d=protrusion_d+protrusion_tolerance_h,h=protrusion_h+protrusion_tolerance_v+1,$fn=2*PI*protrusion_d);
+   // mount screw holes
+   for(zr=[0:90:359]) rotate([0,0,zr]) translate([mount_d/2,0,0]) {
+    translate([0,0,mount_screw_l-mounthole_depth/2-layer_height-1])
+    mirror([0,0,1])
+    cylinder(d=mount_screw_d+mount_screw_d_tolerance,
+             h=mount_screw_l-mounthole_depth/2-layer_height+1,
+             $fn=2*PI*mount_screw_d);
+    translate([0,0,mount_screw_l-mounthole_depth/2])
+    cylinder(d=mount_screwhead_d,h=body_h+1,$fn=2*PI*mount_screwhead_d);
+   }//for
+   // pushfit threads
+   translate([0,0,filament_elevation])
+   rotate([0,0,45]) translate([pulley_d/2,0,0])
+   rotate([-90,0,0])
+   translate([0,0,mount_d/sqrt(2)/2+mount_screw_d+epsilon])
+   rotate([0,0,180]) {
+    pushfit_thread(h=10);
+    cylinder(d=filament_guide_d,h=gearbox_d,center=true,$fn=2*PI*filament_guide_d);
+    translate([0,-filament_guide_d/2/sqrt(2),0])
+    rotate([0,0,45])
+    cube(size=[filament_guide_d/2,filament_guide_d/2,gearbox_d],center=true);
+   }
+   // pulley
+   cylinder(d=pulley_d+pulley_clearance,h=body_h+1,$fn=2*PI*(pulley_d+pulley_clearance));
+   // leverspace
+   hull() for(x=[0,gearbox_d])
+   rotate([0,0,45])
+   translate([x,0,ls_z-ls_h/2])
+   cylinder(d=idler_d+idler_clearance,h=ls_h,$fn=2*PI*idler_d);
+   
+   a=cos(45)*(pulley_d+idler_d)/2;
+   b=mount_d/2-a;
+   x=sqrt(pow(a,2)+pow(b,2));
+   translate([mount_d/2,0,ls_z])
+   intersection() {
+    r = x+idler_d/2+1;/* TODO: */
+    cylinder(r=r,h=ls_h,center=true);
+    translate([-r-1,0,-1]) cube(size=[2*r+2,r+1,ls_h+2]);
+   }
+   
+   rotate([0,0,-45])
+   translate([0,0,ls_z-ls_h/2])
+   cube(size=[gearbox_d,gearbox_d,lever_thickness+lever_v_clearance]);
+   translate([0,0,ls_z-ls_h/2]) {
+    translate([mount_screwhead_d/2,0,0])
+    mirror([0,1,0])
+    cube(size=[gearbox_d,gearbox_d/2+1,lever_thickness+lever_v_clearance]);
+   }
+   //translate([-mount_d/2,-longwing,filament_elevation])
+   translate([mount_d/2,-longwing,filament_elevation])
+   rotate([0,-90,0]) difference() {
+    cylinder(d=spring_d+spring_d_clearance,h=spring_lc+spring_dl,$fn=PI*spring_d);
+    translate([0,0,spring_lc+spring_dl]) sphere(d=spring_d*3/4,$fn=PI*spring_d);
+   }
+   //sphere(d=spring_d*3/4,$fn=PI*spring_d);
+   *difference() {
+    // spring support
+    translate([0,-longwing,filament_elevation])
+    sphere(d=spring_d*3/4,$fn=PI*spring_d);
+   }
+    
+  }//difference
+
+  intersection() {
+   difference() {
+    translate([0,0,ls_z-ls_h/2-epsilon])
+    cylinder(d=gearbox_d,h=ls_h+2*epsilon,$fn=2*PI*gearbox_d);
+    cylinder(d=pulley_d+pulley_clearance,h=body_h+1,$fn=2*PI*(pulley_d+pulley_clearance));
+   }
+   // supports
+   // TODO: hardcoded stuff below…
+   if(false) { // parallel
+    for(y=[-gearbox_d:4:gearbox_d])
+     translate([0,y-extrusion_width/2,0])
+     cube(size=[gearbox_d,extrusion_width,body_h]);
+   }else{ // radial
+    for(zr=[-65:(65+50)/7:50])
+     rotate([0,0,zr]) translate([0,-extrusion_width/2,0])
+     cube(size=[gearbox_d,extrusion_width,body_h]);
+   }
+  }
+
+ }//body module
+ 
+ mirrorleft()
+ if(what=="lever") color("green",0.7) lever();
+ else if(what=="body") color("yellow",0.7) body();
+ else if(what=="both") {
+  color("green",0.7) lever();
+  color("yellow",0.7) body();
+ }
+}
+
+the_extruder(what="both",left=false);
diff --git a/threads.scad b/threads.scad
new file mode 100644
index 0000000..8dd0b7b
--- a/dev/null
+++ b/threads.scad
@@ -0,0 +1,332 @@
+/*

+ * ISO-standard metric threads, following this specification:

+ *          http://en.wikipedia.org/wiki/ISO_metric_screw_thread

+ *

+ * Dan Kirshner - dan_kirshner@yahoo.com

+ *

+ * You are welcome to make free use of this software.  Retention of my

+ * authorship credit would be appreciated.

+ *

+ * Version 1.9.  2016-07-03  Option: tapered.

+ * Version 1.8.  2016-01-08  Option: (non-standard) angle.

+ * Version 1.7.  2015-11-28  Larger x-increment - for small-diameters.

+ * Version 1.6.  2015-09-01  Options: square threads, rectangular threads.

+ * Version 1.5.  2015-06-12  Options: thread_size, groove.

+ * Version 1.4.  2014-10-17  Use "faces" instead of "triangles" for polyhedron

+ * Version 1.3.  2013-12-01  Correct loop over turns -- don't have early cut-off

+ * Version 1.2.  2012-09-09  Use discrete polyhedra rather than linear_extrude ()

+ * Version 1.1.  2012-09-07  Corrected to right-hand threads!

+ */

+

+// Examples.

+//

+// Standard M8 x 1.

+// metric_thread (diameter=8, pitch=1, length=4);

+

+// Square thread.

+// metric_thread (diameter=8, pitch=1, length=4, square=true);

+

+// Non-standard: long pitch, same thread size.

+//metric_thread (diameter=8, pitch=4, length=4, thread_size=1, groove=true);

+

+// Non-standard: 20 mm diameter, long pitch, square "trough" width 3 mm,

+// depth 1 mm.

+//metric_thread (diameter=20, pitch=8, length=16, square=true, thread_size=6, 

+//               groove=true, rectangle=0.333);

+

+// English: 1/4 x 20.

+//english_thread (diameter=1/4, threads_per_inch=20, length=1);

+

+// Tapered.  Example -- pipe size 3/4" -- per:

+// http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html

+// english_thread (diameter=1.05, threads_per_inch=14, length=3/4, taper=1/16);

+

+// Thread for mounting on Rohloff hub.

+//difference () {

+//   cylinder (r=20, h=10, $fn=100);

+//

+//   metric_thread (diameter=34, pitch=1, length=10, internal=true, n_starts=6);

+//}

+

+

+// ----------------------------------------------------------------------------

+function segments (diameter) = min (50, ceil (diameter*6));

+

+

+// ----------------------------------------------------------------------------

+// internal -    true = clearances for internal thread (e.g., a nut).

+//               false = clearances for external thread (e.g., a bolt).

+//               (Internal threads should be "cut out" from a solid using

+//               difference ()).

+// n_starts -    Number of thread starts (e.g., DNA, a "double helix," has

+//               n_starts=2).  See wikipedia Screw_thread.

+// thread_size - (non-standard) size of a single thread "V" - independent of

+//               pitch.  Default: same as pitch.

+// groove      - (non-standard) subtract inverted "V" from cylinder (rather than

+//               add protruding "V" to cylinder).

+// square      - Square threads (per

+//               https://en.wikipedia.org/wiki/Square_thread_form).

+// rectangle   - (non-standard) "Rectangular" thread - ratio depth/width

+//               Default: 1 (square).

+// angle       - (non-standard) angle (deg) of thread side from perpendicular to

+//               axis (default = standard = 30 degrees).

+// taper       - diameter change per length (National Pipe Thread/ANSI B1.20.1

+//               is 1" diameter per 16" length).

+module metric_thread (diameter=8, pitch=1, length=1, internal=false, n_starts=1,

+                      thread_size=-1, groove=false, square=false, rectangle=0,

+                      angle=30, taper=0)

+{

+   // thread_size: size of thread "V" different than travel per turn (pitch).

+   // Default: same as pitch.

+   local_thread_size = thread_size == -1 ? pitch : thread_size;

+   local_rectangle = rectangle ? rectangle : 1;

+

+   n_segments = segments (diameter);

+   h = (square || rectangle) ? local_thread_size*local_rectangle/2 : local_thread_size * cos (angle);

+

+   h_fac1 = (square || rectangle) ? 0.90 : 0.625;

+

+   // External thread includes additional relief.

+   h_fac2 = (square || rectangle) ? 0.95 : 5.3/8;

+

+   if (! groove) {

+      metric_thread_turns (diameter, pitch, length, internal, n_starts,

+                           local_thread_size, groove, square, rectangle, angle,

+                           taper);

+   }

+

+   difference () {

+

+      // Solid center, including Dmin truncation.

+      tapered_diameter = diameter - length*taper;

+      if (groove) {

+         cylinder (r1=diameter/2, r2=tapered_diameter/2,

+                   h=length, $fn=n_segments);

+      } else if (internal) {

+         cylinder (r1=diameter/2 - h*h_fac1, r2=tapered_diameter/2 - h*h_fac1,

+                   h=length, $fn=n_segments);

+      } else {

+

+         // External thread.

+         cylinder (r1=diameter/2 - h*h_fac2, r2=tapered_diameter/2 - h*h_fac2,

+                   h=length, $fn=n_segments);

+      }

+

+      if (groove) {

+         metric_thread_turns (diameter, pitch, length, internal, n_starts,

+                              local_thread_size, groove, square, rectangle,

+                              angle, taper);

+      }

+   }

+}

+

+

+// ----------------------------------------------------------------------------

+// Input units in inches.

+// Note: units of measure in drawing are mm!

+module english_thread (diameter=0.25, threads_per_inch=20, length=1,

+                      internal=false, n_starts=1, thread_size=-1, groove=false,

+                      square=false, rectangle=0, angle=30, taper=0)

+{

+   // Convert to mm.

+   mm_diameter = diameter*25.4;

+   mm_pitch = (1.0/threads_per_inch)*25.4;

+   mm_length = length*25.4;

+

+   echo (str ("mm_diameter: ", mm_diameter));

+   echo (str ("mm_pitch: ", mm_pitch));

+   echo (str ("mm_length: ", mm_length));

+   metric_thread (mm_diameter, mm_pitch, mm_length, internal, n_starts, 

+                  thread_size, groove, square, rectangle, angle, taper);

+}

+

+// ----------------------------------------------------------------------------

+module metric_thread_turns (diameter, pitch, length, internal, n_starts, 

+                            thread_size, groove, square, rectangle, angle,

+                            taper)

+{

+   // Number of turns needed.

+   n_turns = floor (length/pitch);

+

+   intersection () {

+

+      // Start one below z = 0.  Gives an extra turn at each end.

+      for (i=[-1*n_starts : n_turns+1]) {

+         translate ([0, 0, i*pitch]) {

+            metric_thread_turn (diameter, pitch, internal, n_starts, 

+                                thread_size, groove, square, rectangle, angle,

+                                taper, i*pitch);

+         }

+      }

+

+      // Cut to length.

+      translate ([0, 0, length/2]) {

+         cube ([diameter*3, diameter*3, length], center=true);

+      }

+   }

+}

+

+

+// ----------------------------------------------------------------------------

+module metric_thread_turn (diameter, pitch, internal, n_starts, thread_size,

+                           groove, square, rectangle, angle, taper, z)

+{

+   n_segments = segments (diameter);

+   fraction_circle = 1.0/n_segments;

+   for (i=[0 : n_segments-1]) {

+      rotate ([0, 0, i*360*fraction_circle]) {

+         translate ([0, 0, i*n_starts*pitch*fraction_circle]) {

+            current_diameter = diameter - taper*(z + i*n_starts*pitch*fraction_circle);

+            thread_polyhedron (current_diameter/2, pitch, internal, n_starts, 

+                               thread_size, groove, square, rectangle, angle);

+         }

+      }

+   }

+}

+

+

+// ----------------------------------------------------------------------------

+// z (see diagram) as function of current radius.

+// (Only good for first half-pitch.)

+function z_fct (current_radius, radius, pitch, angle)

+   = 0.5* (current_radius - (radius - 0.875*pitch*cos (angle)))

+                                                       /cos (angle);

+

+// ----------------------------------------------------------------------------

+module thread_polyhedron (radius, pitch, internal, n_starts, thread_size,

+                          groove, square, rectangle, angle)

+{

+   n_segments = segments (radius*2);

+   fraction_circle = 1.0/n_segments;

+

+   local_rectangle = rectangle ? rectangle : 1;

+

+   h = (square || rectangle) ? thread_size*local_rectangle/2 : thread_size * cos (angle);

+   outer_r = radius + (internal ? h/20 : 0); // Adds internal relief.

+   //echo (str ("outer_r: ", outer_r));

+

+   // A little extra on square thread -- make sure overlaps cylinder.

+   h_fac1 = (square || rectangle) ? 1.1 : 0.875;

+   inner_r = radius - h*h_fac1; // Does NOT do Dmin_truncation - do later with

+                                // cylinder.

+

+   translate_y = groove ? outer_r + inner_r : 0;

+   reflect_x   = groove ? 1 : 0;

+

+   // Make these just slightly bigger (keep in proportion) so polyhedra will

+   // overlap.

+   x_incr_outer = (! groove ? outer_r : inner_r) * fraction_circle * 2 * PI * 1.02;

+   x_incr_inner = (! groove ? inner_r : outer_r) * fraction_circle * 2 * PI * 1.02;

+   z_incr = n_starts * pitch * fraction_circle * 1.005;

+

+   /*

+    (angles x0 and x3 inner are actually 60 deg)

+

+                          /\  (x2_inner, z2_inner) [2]

+                         /  \

+   (x3_inner, z3_inner) /    \

+                  [3]   \     \

+                        |\     \ (x2_outer, z2_outer) [6]

+                        | \    /

+                        |  \  /|

+             z          |[7]\/ / (x1_outer, z1_outer) [5]

+             |          |   | /

+             |   x      |   |/

+             |  /       |   / (x0_outer, z0_outer) [4]

+             | /        |  /     (behind: (x1_inner, z1_inner) [1]

+             |/         | /

+    y________|          |/

+   (r)                  / (x0_inner, z0_inner) [0]

+

+   */

+

+   x1_outer = outer_r * fraction_circle * 2 * PI;

+

+   z0_outer = z_fct (outer_r, radius, thread_size, angle);

+   //echo (str ("z0_outer: ", z0_outer));

+

+   //polygon ([[inner_r, 0], [outer_r, z0_outer], 

+   //        [outer_r, 0.5*pitch], [inner_r, 0.5*pitch]]);

+   z1_outer = z0_outer + z_incr;

+

+   // Give internal square threads some clearance in the z direction, too.

+   bottom = internal ? 0.235 : 0.25;

+   top    = internal ? 0.765 : 0.75;

+

+   translate ([0, translate_y, 0]) {

+      mirror ([reflect_x, 0, 0]) {

+

+         if (square || rectangle) {

+

+            // Rule for face ordering: look at polyhedron from outside: points must

+            // be in clockwise order.

+            polyhedron (

+               points = [

+                         [-x_incr_inner/2, -inner_r, bottom*thread_size],         // [0]

+                         [x_incr_inner/2, -inner_r, bottom*thread_size + z_incr], // [1]

+                         [x_incr_inner/2, -inner_r, top*thread_size + z_incr],    // [2]

+                         [-x_incr_inner/2, -inner_r, top*thread_size],            // [3]

+

+                         [-x_incr_outer/2, -outer_r, bottom*thread_size],         // [4]

+                         [x_incr_outer/2, -outer_r, bottom*thread_size + z_incr], // [5]

+                         [x_incr_outer/2, -outer_r, top*thread_size + z_incr],    // [6]

+                         [-x_incr_outer/2, -outer_r, top*thread_size]             // [7]

+                        ],

+

+               faces = [

+                         [0, 3, 7, 4],  // This-side trapezoid

+

+                         [1, 5, 6, 2],  // Back-side trapezoid

+

+                         [0, 1, 2, 3],  // Inner rectangle

+

+                         [4, 7, 6, 5],  // Outer rectangle

+

+                         // These are not planar, so do with separate triangles.

+                         [7, 2, 6],     // Upper rectangle, bottom

+                         [7, 3, 2],     // Upper rectangle, top

+

+                         [0, 5, 1],     // Lower rectangle, bottom

+                         [0, 4, 5]      // Lower rectangle, top

+                        ]

+            );

+         } else {

+

+            // Rule for face ordering: look at polyhedron from outside: points must

+            // be in clockwise order.

+            polyhedron (

+               points = [

+                         [-x_incr_inner/2, -inner_r, 0],                        // [0]

+                         [x_incr_inner/2, -inner_r, z_incr],                    // [1]

+                         [x_incr_inner/2, -inner_r, thread_size + z_incr],      // [2]

+                         [-x_incr_inner/2, -inner_r, thread_size],              // [3]

+

+                         [-x_incr_outer/2, -outer_r, z0_outer],                 // [4]

+                         [x_incr_outer/2, -outer_r, z0_outer + z_incr],         // [5]

+                         [x_incr_outer/2, -outer_r, thread_size - z0_outer + z_incr], // [6]

+                         [-x_incr_outer/2, -outer_r, thread_size - z0_outer]    // [7]

+                        ],

+

+               faces = [

+                         [0, 3, 7, 4],  // This-side trapezoid

+

+                         [1, 5, 6, 2],  // Back-side trapezoid

+

+                         [0, 1, 2, 3],  // Inner rectangle

+

+                         [4, 7, 6, 5],  // Outer rectangle

+

+                         // These are not planar, so do with separate triangles.

+                         [7, 2, 6],     // Upper rectangle, bottom

+                         [7, 3, 2],     // Upper rectangle, top

+

+                         [0, 5, 1],     // Lower rectangle, bottom

+                         [0, 4, 5]      // Lower rectangle, top

+                        ]

+            );

+         }

+      }

+   }

+}

+

+