add offset gears

gear-v3.scad

@@ -77,19 +77,23 @@ translate([0, 0, 16])
 
 //clutchGear(32);
 
-/* Gear with clutch fully offset to one side - useful for compact gearbox */
+/* Gear with clutch fully offset to one side - useful for compact gearbox
+   because allows to make clutch gears smaller than 16t */
 
-//offsetClutchGear(23);
+//offsetClutchGear(9, gear_height=4);
+//offsetClutchGear(23, gear_height=3.8);
 
-/* Gear fully offset to one side */
+/* Solid gear fully offset to one side */
 
 //offsetGear(number_of_teeth=8, gear_height=3.8);
-// Sample offset gear with 28 teeth and 4 holes
+
+/* Sample offset gear with 28 teeth and 4 holes */
+
 //gear28_4holes();
 
 /* Gear with offset teeth, axle hole and sparse body */
 
-offsetGearSparse(9, gear_height=3.9);
+//offsetGearSparse(20, gear_height=3.8, jaggy=1);
 
 /* Half-stud parametric gear with some holes */
 
@@ -421,60 +425,62 @@ module pinHole(height=8) {
 }
 
 // Gear with offset teeth, axle hole and sparse body
-module offsetGearSparse(number_of_teeth, gear_height=3.9) {
+module offsetGearSparse(number_of_teeth, gear_height=3.9, jaggy=1) {
   root_radius = 3.05*number_of_teeth/3.1415926/2 - 3.05/3.1415926;
   difference() {
-    offsetGear(number_of_teeth, gear_height);
+    offsetGear(number_of_teeth, gear_height, jaggy);
     translate([0, 0, -0.1])
     difference() {
       cylinder($fn=50, h=gear_height+0.2, r=root_radius-1.5);
       cylinder($fn=50, h=gear_height+0.2, r=3.5);
-      translate([-root_radius-1, 1.5, 0]) cube(size=[root_radius*2+2, 2, 2*gear_height+0.4], center=false);
-      translate([-root_radius-1, -3.5, 0]) cube(size=[root_radius*2+2, 2, 2*gear_height+0.4], center=false);
+      translate([-root_radius-1, 3.1-0.75, 0]) cube(size=[root_radius*2+2, 1.5, 2*gear_height+0.4], center=false);
+      translate([-root_radius-1, -3.1-0.75, 0]) cube(size=[root_radius*2+2, 1.5, 2*gear_height+0.4], center=false);
       rotate([0, 0, 90]) {
-        translate([-root_radius-1, 1.5, 0]) cube(size=[root_radius*2+2, 2, 2*gear_height+0.4], center=false);
-        translate([-root_radius-1, -3.5, 0]) cube(size=[root_radius*2+2, 2, 2*gear_height+0.4], center=false);
+        translate([-root_radius-1, 3.1-0.75, 0]) cube(size=[root_radius*2+2, 1.5, 2*gear_height+0.4], center=false);
+        translate([-root_radius-1, -3.1-0.75, 0]) cube(size=[root_radius*2+2, 1.5, 2*gear_height+0.4], center=false);
       }
     }
   }
 }
 
 // Gear with offset teeth and axle hole
-module offsetGear(number_of_teeth, gear_height=3.9) {
+module offsetGear(number_of_teeth, gear_height=3.9, jaggy=1) {
   difference() {
     union() {
       gear(number_of_teeth=number_of_teeth, mm_per_tooth=3.05, thickness=gear_height, clearance=-0.1);
       translate([0, 0, gear_height]) cylinder($fs=0.5, h=8-gear_height, r=3.5);
     }
     // axle hole
-    axle(0, 0, -1, 10);
+    rotate([0, 0, -jaggy*360/number_of_teeth]) axle(0, 0, -1, 10);
   }
 }
 
 // Gear with interface for driving ring, with offset teeth
 // => The minimal printable size of such gear is 9 teeth...
 // (8 teeth will probably be too thin at root circle)
-module offsetClutchGear(number_of_teeth) {
+module offsetClutchGear(number_of_teeth, gear_height=3.8) {
   union() {
     difference() {
       union() {
-        gear(number_of_teeth=number_of_teeth, mm_per_tooth=3.05, thickness=4);
-        translate([0, 0, 3.9]) cylinder($fn=max(32,2*number_of_teeth), h=4.1, r=6.8);
+        gear(number_of_teeth=number_of_teeth, mm_per_tooth=3.05, thickness=gear_height+0.1);
+        translate([0, 0, gear_height]) cylinder($fn=max(32,2*number_of_teeth), h=8-gear_height, r=6.8);
       }
       difference() {
         translate([0, 0, 4.8]) cylinder($fn=50, h=4, r=5.8);
         translate([0, 0, 4.8]) cylinder($fn=50, h=4, r=3.3);
       }
-      difference() {
-        translate([0, 0, -0.1]) cylinder($fn=50, h=2.9+0.1, r=3.05*(number_of_teeth/2-1)/3.1415926-1);
-        translate([0, 0, -0.2]) cylinder($fn=50, h=4, r=3.5);
-        translate([-0.5, -20, -0.1]) cube(size=[1, 40, 10]);
-        translate([-20, -0.5, -0.1]) cube(size=[40, 1, 10]);
+      if (number_of_teeth > 13) {
+        difference() {
+          translate([0, 0, -0.1]) cylinder($fn=50, h=gear_height-1+0.1, r=3.05*(number_of_teeth/2-1)/3.1415926-1);
+          translate([0, 0, -0.2]) cylinder($fn=50, h=4, r=3.5);
+          translate([-0.5, -20, -0.1]) cube(size=[1, 40, 10]);
+          translate([-20, -0.5, -0.1]) cube(size=[40, 1, 10]);
+        }
       }
       // round hole
       translate([0, 0, -2]) cylinder($fn=50, h=12, r=2.5);
     }
-    translate([0, 0, 3]) union() {
+    translate([0, 0, 2.9]) union() {
       clutchTeeth();
       rotate([0, 0, 90]) clutchTeeth();
       rotate([0, 0, 180]) clutchTeeth();