Work (not yet completed) on the lower knuckles of the four bar linkage.

model/fourbar.scad

@@ -34,21 +34,51 @@ module fourbar_leg(length=1000, chord=100, long_skew=30, lat_skew=30) {
 }
 
 
-module fourbar_axle_half( length, chord) {
-    translate([0, 0, -120])
-        rotate([82, 0, 180])
+module lower_knuckle(chord=100, pivot_radius=12) {
+    difference() {
+        cube([chord * 1.5, pivot_radius * 3, chord*.66]);
+        translate([ chord*0.25, -1, pivot_radius * 2])
+            cube([chord, pivot_radius * 4, pivot_radius * 4]);
+    }
+}
+
+module fourbar_axle_half( length, chord, long_skew) {
+    shoulder=650;
+    lat_skew=30;
+    rise=8;
+    
+    // I've got something wrong in computing the half-lower-bar
+    // length, and I don't know what.
+    fudge=0;
+    
+    w = ((length * sin(lat_skew) ) + ( shoulder / 2));
+    l_hlb= w * (1/cos(rise)) + fudge;
+    v_offset=l_hlb * sin(rise);
+
+    echo("long_skew", long_skew);
+    
+    translate([0, 0, 0 - v_offset])
+        rotate([90-rise, 0, 180])
         color("black")
-        airfoil(h=length, L=chord);
+        airfoil(h=l_hlb, L=chord);
     
     // lower knuckle
-    translate([-chord, length, -60])
+    translate([(0 - (chord*1.25)), l_hlb * cos(rise), 30])
+        rotate([0, long_skew, 0])
         color("black")
-        cube([chord, chord/4, chord/2]);
+        lower_knuckle(chord, 12);
        
     // wheel
-    translate([0, length + 50, -50])
+    translate([-50, l_hlb + 72, -40])
         rotate([270, 0, 0])
         wheel(iso=451); 
+        
+    // brake disk
+    translate([-50, l_hlb + 35, -40])
+        color("silver")
+        rotate([90, 0, 0])
+        cylinder(h=1.5, r=75);
+    // brake caliper
 }
 
 
@@ -64,11 +94,12 @@ module fourbar(length=1000, chord=100, long_skew=30, lat_skew=30, shoulder=650)
         mirror([0, 1, 0])
         fourbar_leg(length, chord, long_skew, lat_skew);
     
-    fourbar_axle_half(w, chord);
+    fourbar_axle_half(w, chord, long_skew);
     
     mirror([0, 1, 0])
-        fourbar_axle_half(w, chord);
+        fourbar_axle_half(w, chord, long_skew);
 }
 
-
+// lower_knuckle();
 // fourbar();
+// fourbar_axle_half(1000,100, 30);

model/hull.scad

@@ -36,7 +36,7 @@ module hull() {
     intersection() {
         translate([1850,0,500])
             rotate([180, 90, 0])
-            scale([20, 15.5, 15.5])
+            scale([20, 17.5, 15.5])
             rotate_extrude()
             import("library/hull-volume-of-rotation.svg");
         
@@ -52,12 +52,12 @@ module hull() {
         difference() {
             skin(
                 [ellipse($fn=64,r=[350,30]),
-                 ellipse($fn=64,r=[430,340])], 
+                 ellipse($fn=64,r=[430,372])], 
                  z=[0,1200],
                 slices=40,sampling="length",method="reindex");
             skin(
                 [ellipse($fn=64,r=[344,24]),
-                 ellipse($fn=64,r=[424,334])],
+                 ellipse($fn=64,r=[424,366])],
                  z=[-1,1201],
                 slices=40,sampling="length",method="reindex");
         }

model/tricycle.scad

@@ -16,15 +16,6 @@ fourbar(700, 100, 30, 35, 650);
 
 translate([800, 0, 120])
 rotate([0, 4, 0])
-color("forestgreen")
+color("darkolivegreen")
 hull();
 
-/* 
-prop=0.1;
-seat_ang=0;
-leg_ang=0;
-left_fold=0;
-head_ang=0;
-leg_prop=0.5;
-
-vRider(prop, seat_ang, leg_ang, left_fold, head_ang, leg_prop);*/