# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1389402047 -3600
# Node ID 3a3c5c3ff80ea7b58ffcc980fd7162870d474606
# Parent  71fe803717c1bbe9157f5e716d64242b15ed65f5
Added the back outer cavity in the cartridge.

diff -r 71fe803717c1 -r 3a3c5c3ff80e cartridge.scad
--- a/cartridge.scad	Sat Jan 11 01:12:34 2014 +0100
+++ b/cartridge.scad	Sat Jan 11 02:00:47 2014 +0100
@@ -38,6 +38,14 @@
 
 	groove_depth = 1.0;
 
+	back_cavity_width = 68.0;
+	back_cavity_inner_width = 65.0;
+	back_cavity_offset_from_left = 10.5;
+	back_cavity_inner_offset_from_left = 12.0;
+	back_cavity_height = 13.5;
+	back_cavity_inner_height = 12.0;
+	back_cavity_depth = 1.5;
+
 	/* Side thicknesses. */
 
 	front = 2;
@@ -90,17 +98,54 @@
 			/* Left groove. */
 
 			translate([-width / 2 + groove_depth / 2, 0, 0])
-				cube([groove_depth, groove_depth, height], center = true);
+				cube([groove_depth, groove_depth, height],
+					center = true);
 
 			/* Right groove. */
 
 			translate([width / 2 - groove_depth / 2, 0, 0])
-				cube([groove_depth, groove_depth, height], center = true);
+				cube([groove_depth, groove_depth, height],
+					center = true);
 
 			/* Top groove. */
 
 			translate([0, 0, height / 2 - groove_depth / 2])
-				cube([width, groove_depth, groove_depth], center = true);
+				cube([width, groove_depth, groove_depth],
+					center = true);
+		}
+
+		/* Back cavity. */
+
+		intersection() {
+
+			/* From the bottom upwards. */
+
+			translate([0, depth / 2, -height / 2])
+				linear_extrude(height = back_cavity_height)
+					translate([-width / 2, 0, 0])
+						polygon([
+							[back_cavity_offset_from_left, 0],
+							[back_cavity_inner_offset_from_left,
+								-back_cavity_depth],
+							[back_cavity_inner_offset_from_left +
+								back_cavity_inner_width,
+								-back_cavity_depth],
+							[back_cavity_offset_from_left +
+								back_cavity_width, 0]
+							]);
+
+			/* From left to right. */
+
+			translate([back_cavity_width / 2, depth / 2, -height / 2])
+				rotate([0, -90, 0])
+					linear_extrude(height = back_cavity_width)
+						polygon([
+							[-extra, -back_cavity_depth],
+							[back_cavity_inner_height,
+								-back_cavity_depth],
+							[back_cavity_height, 0],
+							[-extra, 0]
+							]);
 		}
 
 		/* Fillets to round off the edges. */