cable-splice-clamp: introduce top and basew, and size top thickness by r1

[reprap-play.git] / cable-splice-clamp.scad

diff --git a/cable-splice-clamp.scad b/cable-splice-clamp.scad
index a2c64e891019b23b26050ed49cdb525a46006272..55f219a0bf65a293ec5457b627eb1b6b0572f3f4 100644 (file)
--- a/cable-splice-clamp.scad
+++ b/cable-splice-clamp.scad
@@ -1,25 +1,89 @@
 // -*- C -*-
 
-cable_maxdia = 12;
-cable_mindia = 6;
+include <commitid.scad>
 
-wallmin = 1;
-wall = 2;
+rnom = 9;
 
-delta_ellipse = 0.5;
+// alpha is slope angle, which is half of inner concave angle that
+//  wire sits in
+alpha = 40; // degrees
 
-// calculated
+// mu is minimum number of cable radii that cable tangent point (line)
+//  with splint ought to be away from edge of split
+mu = 1/4;
 
-outerdia = cable_maxdia / cos(30) + wall*2;
-delta_shift = 1 - delta_ellipse;
+// wall thickness, and base width as fraction of cable size
+wall_r = 1.5 / 6.5;
+base_r = 0.75;
 
-module CrossSection() {
+// for cross-section calculations:
+//
+// origin O is at intersection of straight line segments forming walls
+// C is centre of circle (wire x-section) (of radius r or radius 1)
+//       which is tangent to lines
+// T is said tangent points
+// B is inner base point, which is extension of line from B by mu*r
+
+sina = sin(alpha);
+cosa = cos(alpha);
+tana = sina/cosa;
+
+// blah_r is blah where r=1
+// d_AB is distance AB
+// dy_AB is " " " vertical component
+
+d_OT_r = tana;
+d_OB_r = tana + mu;
+
+d_OC_r = 1/cosa;
+
+dy_OB_r = d_OB_r * sina;
+
+// *0 and *1 relate to smallest and largest wire
+// r[01] is radius
+// r10 is radius ratio
+
+r10 = d_OC_r / dy_OB_r;
+
+r0 = rnom / sqrt(r10);
+r1 = rnom * sqrt(r10);
+
+x_B_r =   d_OB_r * cosa;
+y_B_r = -dy_OB_r;
+
+x_T_r =         sina;
+y_T_r = -tana * sina;
+
+top_r = wall_r - (d_OC_r - 1);
+
+wall_x_r = wall_r / tan(90-alpha);
+
+top = top_r * r1;
+basew = base_r * rnom;
+
+echo(r0,r1, "ratio",r1/r0);
+
+module CrossSection(plus=0) {
   difference(){
-    cylinder(r= outerdia/2, $fn=6);
-    scale([cable_maxdia,
-          cable_maxdia * delta_shift + cable_mindia * delta_ellipse])
-      cylinder(r= 0.5, $fn=30);
+    polygon([[-0.1,                                y_T_r * r0],
+            [x_T_r * r0,                          y_T_r * r0],
+            [x_B_r * r1,                          y_B_r * r1],
+            [x_B_r * r1 + wall_x_r * rnom + plus, y_B_r * r1],
+            [basew                        + plus, top],
+            [-0.1,                                top]]);
+    translate([0, -d_OC_r * r0])
+      circle(r = r0);
+  }
+}
+
+module CrossSectionDemo(){ ////toplevel
+  color("black") CrossSection(2);
+  CrossSection();
+  for (rc=[["red", r1],
+          ["blue",r0]]) {
+    color(rc[0]) translate([0, -d_OC_r * rc[1]]) circle(r = rc[1]);
   }
 }
 
-CrossSection();
+//CrossSection();
+CrossSectionDemo();