X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=reprap-play.git;a=blobdiff_plain;f=cable-splice-clamp.scad;h=f71c848756b259723e6fcb078acf912114ec9a5f;hp=7533bcdf9ff4626741427e26bd6349948963a355;hb=6371b5cb46cde0d570f2283d800d0c674e265873;hpb=a0ece72c445d38570668fc4f5319b44c96c4336f

diff --git a/cable-splice-clamp.scad b/cable-splice-clamp.scad
index 7533bcd..f71c848 100644
--- a/cable-splice-clamp.scad
+++ b/cable-splice-clamp.scad
@@ -1,91 +1,138 @@
 // -*- C -*-
 
-cable_maxdia = 12;
-cable_mindia = 6;
-strap_width = 4 + 0.5;
-total_len = 70;
+include <commitid.scad>
 
-wallmin = 1.5;
+rnom = 3.5 / 2;
 
-strap_count = 2;
+// alpha is slope angle, which is half of inner concave angle that
+//  wire sits in
+alpha = 40; // degrees
 
-strap_wall_h = 1.5;
-strap_wall_l = 2.0;
+// 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;
 
-delta_ellipse = 0.45;
+// wall thickness, and base width as fraction of cable size
+wall_r = 2.5 / 6.5;
+base_r = 0.75;
 
-// calculated
+total_len = 60;
 
-delta_shift = 1 - delta_ellipse;
+strap_width = 3.0 + 0.5;
 
-roundoff_rad = cable_maxdia/2 * sqrt(delta_shift)
-	      + cable_mindia/2 * (1-sqrt(delta_shift));
+strap_count = 4;
 
-outerdia = 2*(roundoff_rad / cos(30) + wallmin);
+// 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
 
-delta_shift_gap = (cable_maxdia-cable_mindia) * delta_shift;
+sina = sin(alpha);
+cosa = cos(alpha);
+tana = sina/cosa;
 
-module CrossSection(plus=0) {
+// 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;
+
+wall_x_r = wall_r / tan(90-alpha);
+
+top = wall_r * r1 - (d_OC_r - 1) * r0;
+basew = base_r * rnom;
+
+echo("dias", r0*2, r1*2, "ratio",r1/r0);
+
+module CrossSectionHalf(plus=0) {
   difference(){
-    for (dx = [-plus, 0, plus])
-      translate([dx, 0])
-      circle(r= outerdia/2, $fn=6);
-
-    intersection(){
-      scale([cable_maxdia,
-	     cable_maxdia * delta_shift + cable_mindia * delta_ellipse])
-	circle(r= sqrt(0.5) * delta_shift + 0.5 * delta_ellipse, $fn=4);
-      circle(r= roundoff_rad, $fn=20);
-    }
+    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);
+  }
+}
 
-    square(center=true, [40, delta_shift_gap]);
+module CrossSection(plus=0) {
+  for (m=[0,1]) {
+    mirror([m,0])
+      CrossSectionHalf(plus);
   }
 }
 
 module CrossSectionDemo(){ ////toplevel
-  color("blue"){
-    translate([0, delta_shift_gap/2, 0]){
-      difference(){
-        circle(r = cable_maxdia/2, $fn=20);
-	circle(r = cable_mindia/2, $fn=20);
-      }
-    }
+  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]);
   }
-  
-  linear_extrude(height=20)
-    CrossSection(0);
-
-  color("red")
-    linear_extrude(height=1)
-    CrossSection(2);
 }
 
-module CompleteClamp(){ ////toplevel
-  linear_extrude(height=total_len)
-    CrossSection();
-
-  for (i=[0 : strap_count]){
-    if (i*2 != strap_count) {
-      translate([0, 0,
-		 total_len * (i + 0.5) / (strap_count + 1)])
-	for (m=[0,1]){
-	  mirror([0,0,m])
-	    translate([0,0, strap_width/2])
-	    linear_extrude(height=strap_wall_l)
-	    CrossSection(strap_wall_h);
+strap_wall_h = 1.5;
+strap_wall_l = 2.0;
+
+writing_dx = total_len / 3;
+writing_dy = basew*2;
+
+module HalfClamp(){ ////toplevel
+  difference(){
+    rotate([90,0,0])rotate([0,90,0]){
+      linear_extrude(height=total_len)
+	CrossSection();
+
+      for (i=[0 : strap_count]){
+	if (i*2 != strap_count) {
+	  translate([0, 0,
+		     total_len * (i + 0.5) / (strap_count + 1)])
+	    for (m=[0,1]){
+	      mirror([0,0,m])
+		translate([0,0, strap_width/2])
+		linear_extrude(height=strap_wall_l)
+		CrossSection(strap_wall_h);
+	    }
 	}
+      }
     }
+
+    translate([0, -basew, top])
+      Commitid_BestCount([writing_dx, writing_dy]);
   }
 }
 
-module HalfPrint(){ ////toplevel
-  intersection(){
-    rotate([-90,0,-90])
-      CompleteClamp();
-    translate([-100,-100,0]) cube([1000,200,200]);
-  }
+module HalfClampPrint(){ ////toplevel
+  rotate([180,0,0])
+    HalfClamp();
 }
 
+//CrossSection();
 //CrossSectionDemo();
-//CompleteClamp();
-HalfPrint();
+//HalfClamp();
+HalfClampPrint();