Added pulleys, bom item listing

stock_parts.scad

@@ -1,3 +1,6 @@
+include <MCAD/math.scad>;
+include <lib.scad>;
+
 stock_color = "#aaa4";
 
 bushing_od = 12;
@@ -15,6 +18,7 @@ module colorize(colorname) {
 }
 
 module bushing() {
+  bom_item(printable=false, label="Bushing");
   colorize(stock_color) render() {
     difference() {
       cylinder(d = bushing_od, h = bushing_len);
@@ -26,6 +30,7 @@ module bushing() {
 
 // located with the shaft in +z, face on the XY plane 
 module nema17(depth = 23.5) {
+  bom_item(printable=false, label="NEMA-17 stepper motor");
   face = 42.3;
   screw_pitch = 31 / 2;
   color(stock_color)
@@ -51,3 +56,65 @@ module nema17(depth = 23.5) {
   }
 
 }
+
+// belts and pulleys
+belt_pitch = 2; // 2mm tooth width for GT2 = 2mm pitch
+belt_width = 6;
+belt_thickness = 3;
+tooth_height = 2;
+
+module pulley(teeth, lrim, urim, belt_width, shaft=5, toothed=true) {
+  bom_item(printable=false, label=str(
+    toothed ? "pulley(" : "idler(",
+    "teeth=", teeth, ", ",
+    "flange1=", min(lrim, urim), "mm, ",
+    "flange2=", max(lrim, urim), "mm, ",
+    "channel=", belt_width, "mm, ",
+    "shaft=", shaft, "mm",
+    ")"
+  ));
+  inner_rad = belt_pitch * teeth / TAU;
+  outer_rad = inner_rad + belt_thickness;
+  minor_rad = inner_rad - tooth_height;
+  mid_rad = inner_rad - tooth_height / 2;
+
+  dtheta = 180 / teeth;
+
+  tooth_points = [
+    for (i = [1:1:teeth])
+    let (theta = i * 360 / teeth)
+    each [
+      [sin(theta) * minor_rad, cos(theta) * minor_rad],
+      [sin(theta) * inner_rad, cos(theta) * inner_rad],
+      [sin(theta + dtheta) * inner_rad, cos(theta + dtheta) * inner_rad],
+      [sin(theta + dtheta) * minor_rad, cos(theta + dtheta) * minor_rad]
+    ]
+  ];
+
+  //echo([each [0:1:teeth]]);
+
+  //echo(tooth_points);
+
+  colorize(stock_color)
+  render()
+  difference() {
+    union() {
+      cylinder(r=outer_rad, h=lrim);
+      translate([0,0,lrim])
+      if (toothed) {
+        linear_extrude(belt_width)
+        polygon(tooth_points, convexity = teeth * 2 + 4);
+      } else {
+        cylinder(r = minor_rad, h = belt_width);
+      }
+
+      translate([0,0,lrim + belt_width])
+      cylinder(r=outer_rad, h=urim);
+    }
+
+    translate([0,0,-1])
+    cylinder(d=shaft, h=belt_width + lrim + urim + 2);
+  }
+}
+
+//!pulley(12, 6, 2, toothed=false);