X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=reprap-play.git;a=blobdiff_plain;f=brompton-computer-guard.scad;h=35b0a182b6e9849e80609278345c2121e857b2ee;hp=114c5e3f064113e453537869d1d7b11c85f0c3d1;hb=7c8e5269fcdeb704dbf43f31cbd60319129df6e2;hpb=bd8a33bdbba529800d92c6e3fbab6c0c92ba56f3;ds=sidebyside

diff --git a/brompton-computer-guard.scad b/brompton-computer-guard.scad
index 114c5e3..35b0a18 100644
--- a/brompton-computer-guard.scad
+++ b/brompton-computer-guard.scad
@@ -1,2 +1,106 @@
 // -*- C -*-
 
+arch_height = 18;
+arch_width = 75;
+end_width = 25;
+
+arch_thick = 4;
+
+arch_breadth = 25;
+
+hole_dia = 4 + 0.5;
+
+pbase_tab = 12;
+pbase_thick = 4;
+
+// computed
+
+arch_alpha = atan(arch_height / (arch_width/2));
+arch_beta = 2*arch_alpha;
+echo(arch_alpha,arch_beta);
+arch_in_rad = arch_width/2 / sin(arch_beta);
+arch_to_chord = arch_in_rad * cos(arch_beta);
+
+inner_pbase_thick = 8;
+echo(inner_pbase_thick);
+
+inner_pbase_rad = arch_in_rad * 2;
+
+end_thick = arch_thick;
+
+holes = [[[  5  , 5  ], [16  , 21]], // left
+	 [[ 18.5, 4.5], [ 4.5, 21]]]; // right
+
+module ArchCircle(rad){
+  translate([0,-arch_to_chord])
+    circle(rad, $fa=0.1);
+}
+
+module ArchProfile(pbase){
+  intersection(){
+    translate([-200,0])
+      square([400,200]);
+    difference(){
+      union(){
+	ArchCircle(arch_in_rad + arch_thick);
+	for (m=[0,1])
+	  mirror([m,0])
+	    translate([arch_width/2,0])
+	    multmatrix([[1,pbase ? -0.75 : 0,0,0],
+			[0,1,0,0],
+			[0,0,1,0],
+			[0,0,0,1]])
+	    square([end_width, pbase ? pbase_tab : end_thick]);
+      }
+    }
+  }
+}
+
+module Holes(){
+  for (m=[0,1]) {
+    mirror([1-m,0])
+      translate([arch_width/2, 50, 0])
+      rotate([90,0,0])
+      for (h=holes[m]) {
+	translate(h)
+	  cylinder(r=hole_dia/2, h=100, $fn=20);
+      }
+  }
+}
+
+module MainCutout(){
+  ArchCircle(arch_in_rad);
+}
+
+module Arch(){
+  difference(){
+    rotate([0,0,180]){
+      linear_extrude(height=arch_breadth) {
+	difference(){
+	  ArchProfile(false);
+	  MainCutout();
+	}
+      }
+      difference(){
+	translate([0,0, arch_breadth - pbase_thick])
+	linear_extrude(height=pbase_thick){
+	  difference(){
+	    hull(){
+	      ArchProfile(true);
+	      ArchProfile(false);
+	    }
+	    intersection(){
+	      MainCutout();
+	      translate([0, -inner_pbase_thick
+			 - (inner_pbase_rad - arch_in_rad)])
+		ArchCircle(inner_pbase_rad);
+	    }
+	  }
+	}
+      }
+    }
+    Holes();
+  }
+}
+
+rotate([0,0,45]) translate([0,0,arch_breadth]) rotate([0,180,0]) Arch();