--- /dev/null
+// -*- C -*-
+
+tube_dia = 48.3;
+
+th = 6;
+
+pin_gap = 1.0; // around
+
+// calculated
+
+pin_dia = th;
+hole_dia = th + pin_gap;
+
+hinge_o_r = 0.5 * hole_dia + th;
+
+hinge_x = -0.5 * tube_dia - hinge_o_r;
+
+module Plan() {
+ union(){
+ translate([hinge_x, 0]) circle(r= hinge_o_r);
+ circle(r = tube_dia/2 + th);
+ }
+}
+
+Plan();