Works very well now

latch.scad

@@ -6,48 +6,79 @@
 
 $fn = $preview ? 32 : 64;
 
-module _top_post(thickness, axis, ridge, funnel, tol) {
-    overlap = ridge+tol;
-    dia = 2*thickness+axis;
-    f_diag = (axis+2*funnel)/sqrt(2);
+// Thickness of walls
+thickness = 3.0; // [2:5:.5]
+
+// Diameter of axle
+axle = 2.5;      // [2:5:.5]
+
+// Clearance above bottom
+clearance = 3;   // [0:10:1]
+
+// Width of latch
+width = 10;      // [5:50:1]
+
+// Length of latch
+length = 20;     // [5:100:1]
+
+/* Other parameters - tune if necessary */
+// Tolerance of parts
+tolerance = .2;  // [0:1:.1]
+
+module _top_post(THICK, AXLE, CLEAR, TOL) {
+    dia = 2*THICK+AXLE;
+    center = AXLE/2+CLEAR;
+    f_diag = (2*AXLE)/sqrt(2);
     difference() {
         union() {
-            translate([0, -dia/2, 0]) cube([thickness, dia, dia/2+overlap]);
-            translate([thickness, 0, dia/2+overlap]) rotate([0, -90, 0]) cylinder(h=thickness, d=dia);
+            translate([0, -dia/2, 0]) cube([THICK, dia, AXLE/2+CLEAR]);
+            translate([THICK, 0, center]) rotate([0, -90, 0]) cylinder(h=THICK, d=dia);
         }
-        translate([thickness, 0, dia/2+overlap]) rotate([0, -90, 0]) cylinder(h=thickness, d=axis+tol);
-        translate([0, 0, dia/2-axis/2+overlap]) cube([thickness, dia/2, axis]);
-        translate([0, dia/2, dia/2+overlap+tol]) rotate([-45, 0, 0]) translate([0, -f_diag/2, -f_diag/2]) cube([thickness, f_diag, f_diag]);
+        translate([THICK, 0, center]) rotate([0, -90, 0]) cylinder(h=THICK, d=AXLE+TOL);
+        translate([0, AXLE/2, CLEAR]) rotate([90, 0, 90]) linear_extrude(THICK) polygon([[0, TOL/2], [0, AXLE-TOL/2], [dia/2, 1.5*AXLE], [dia/2, -0.5*AXLE]]);
+        translate([0, 0, CLEAR+TOL]) cube([THICK, AXLE/2, AXLE-2*TOL]);
+        translate([0, -dia, -dia]) cube([THICK, dia, dia]);
     }
 }
 
-module latch_top(spacing=10, thickness=3, axis=2.5, ridge=.7, funnel=.7, tol=.2) {
-    translate([spacing/2, 0, 0])      _top_post(thickness, axis, ridge, funnel, tol);
-    translate([-spacing/2-thickness, 0, 0]) _top_post(thickness, axis, ridge, funnel, tol);
+module latch_top(WIDTH=width, THICK=thickness, AXLE=axle, CLEAR=clearance, TOL=tolerance) {
+    translate([WIDTH/2+TOL, 0, 0])        _top_post(THICK, AXLE, CLEAR, TOL);
+    translate([-WIDTH/2-THICK-TOL, 0, 0]) _top_post(THICK, AXLE, CLEAR, TOL);
 }
 
-module latch_tongue(length=20, width=10, thickness=3, axis=2.5, ridge=.7, tol=.2) {
-    overlap = ridge+thickness;
-    translate([width+thickness, 0, thickness/2]) rotate([0, -90, 0]) cylinder(h=width+2*thickness, d=axis);
+module latch_tongue(LENGTH=length, WIDTH=width, THICK=thickness, AXLE=axle, TOL=tolerance) {
+    angle = 50;
+    mid   = THICK/2;
+    translate([0, 0, THICK]) linear_extrude(WIDTH) {
         hull() {
-        translate([width-tol, 0, thickness/2]) rotate([0, -90, 0]) cylinder(h=width-tol, d=thickness);
-        translate([width-tol, length+thickness-.5, .5]) rotate([0, -90, 0]) cylinder(h=width-tol, d=1);
-        translate([0, thickness/2, thickness/2]) cube([width-tol, length+thickness/2, thickness/2]);
+            translate([mid, 0]) circle(d=THICK);
+            translate([AXLE/2+THICK, 0]) circle(d=AXLE);
         }
-    translate([0, length, thickness]) cube([width-tol, thickness, overlap+ridge-.5]);
         hull() {
-        translate([width-tol, length, thickness+overlap+ridge/2]) rotate([0, -90, 0]) cylinder(h=width-tol, d=ridge);
-        translate([width-tol, length+thickness-.5, thickness+overlap+ridge-.5]) rotate([0, -90, 0]) cylinder(h=width-tol, d=1);
+            translate([mid, 0]) circle(d=THICK);
+            translate([mid, -LENGTH-3*AXLE]) circle(d=THICK);
         }
+        difference() {
+            translate([AXLE/2+THICK, -LENGTH+AXLE/2]) circle(d=2*THICK+AXLE);
+            translate([AXLE/2+THICK, -LENGTH+AXLE/2]) circle(d=AXLE+TOL);
+            translate([THICK, -LENGTH+AXLE/2]) square([AXLE, THICK]);
+            translate([AXLE/2+THICK, -LENGTH+AXLE/2]) rotate(-angle) translate([-50, 0]) square(100, 100);
+        }
+        translate([AXLE/2+THICK+sin(angle)*(AXLE+THICK)/2, -LENGTH+AXLE/2-cos(angle)*(AXLE+THICK)/2]) circle(d=THICK);
+    }
+    translate([AXLE/2+THICK, 0]) cylinder(h=WIDTH+2*THICK, d=AXLE);
 }
 
-module latch_catch(width=10, thickness=3, axis=2.5, ridge=.7, tol=.2) {
-    overlap = ridge;
-    translate([-width/2, 0, 0]) cube([width-tol, thickness, (thickness+ridge)/2+overlap]);
-    translate([width/2-tol, 0, thickness/2+overlap]) rotate([0, -90, 0]) cylinder(h=width-tol, d=ridge);
+module latch_catch(WIDTH=width, THICK=thickness, AXLE=axle, CLEAR=clearance, TOL=tolerance) {
+    center = AXLE/2+CLEAR;
+    translate([WIDTH/2+THICK+TOL, AXLE/2, center]) rotate([0, -90, 0]) cylinder(h=WIDTH+2*THICK+2*TOL, d=AXLE);
+    translate([WIDTH/2+TOL, 0, 0]) cube([THICK, AXLE, center]);
+    translate([-WIDTH/2-THICK-TOL, 0, 0]) cube([THICK, AXLE, center]);
 }
 
-translate([-8, -20, 0]) cube([16, 24.25, 3]);
+translate([0, 0, 8.2]) rotate([0, 90, 0]) {
+    translate([-8.2, -20, 0]) cube([16.4, 24.25, 3]);
     translate([0, 0, 3]) latch_top();
-translate([20, 0, 0]) mirror([0, 1, 0]) latch_tongue();
     translate([0, -20, 3]) latch_catch();
+}
+translate([20, 0, 0]) latch_tongue();