# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1412699446 -7200
# Node ID f6f352022ef4a88145c1ce73703fa641166748ac
# Parent  bd66a16190dbc4c8df96b8849d41f568007af89f
Changed the back dimensions to only incorporate a minimum overlap, with extra
overlapping material considered separately.
Simplified definitions for the back and front inner cutout (accommodating extra
overlapping material).

diff -r bd66a16190db -r f6f352022ef4 cartridge.scad
--- a/cartridge.scad	Tue Oct 07 15:20:20 2014 +0200
+++ b/cartridge.scad	Tue Oct 07 18:30:46 2014 +0200
@@ -77,33 +77,37 @@
 	/* Internal dimensions. */
 
 	int_width = 86.0;
-	int_payload_height = 51.8;	/* includes bottom of payload area */
-	int_connector_height = 13.5; 	/* height of bottom/floor of payload area */
 	int_depth = 11.0;
+	int_payload_height = 50.8;	/* space between the top and the floor */
+	int_connector_height = 13.5; 	/* vertical offset of bottom/floor of payload area */
 
 	/* Side thicknesses. */
 
 	front = 2;
 	back = 3.5;
 	top = 3;
-	side = 2; /* increased from 1.5 for 3D printing reliability */
+	side = 2; 			/* increased from 1.5 for 3D printing reliability */
+	bottom = 1;			/* thickness of floor of payload area */
 
 	/* How much extra depth the back provides for mating with the front. */
 
-	groove_width_extra = 2.0;
+	groove_width_extra = 1.0;
+	front_back_overlap = 1.0;
+	groove_width_overlap = front_back_overlap + groove_width_extra;
 
 	/* Division of pieces into front and back, defining the extents. */
 
 	int_front_depth = 4.5;
 	front_depth = int_front_depth + front;
-	int_back_depth = int_depth - int_front_depth + groove_width_extra;
+	int_back_depth = int_depth - int_front_depth + front_back_overlap;
 	back_depth = int_back_depth + back;
 
 	/* Cartridge dimensions. */
 
 	width = int_width + side + side;
-	height = int_payload_height + int_connector_height + top;
+	height = top + int_payload_height + bottom + int_connector_height;
 	depth = int_depth + front + back;
+	int_payload_upper_extent = height / 2 - top;
 
 	/* Cartridge surfaces. */
 
@@ -113,7 +117,6 @@
 	back_side = side;
 	back_left = back_side;
 	back_right = back_side;
-	bottom = 1;
 
 	/* Label details. */
 
@@ -134,12 +137,12 @@
 	*/
 
 	groove_width_exposed = GROOVE ? 1.5 : 0;
-	groove_width = groove_width_exposed + groove_width_extra;
+	groove_width = groove_width_exposed + groove_width_overlap;
 	groove_depth = 1.0; /* how deep the groove goes into each side */
 
 	/* Additional cutting to mate the back and front. */
 
-	top_groove_width = groove_width_extra;
+	top_groove_width = groove_width_overlap;
 	top_groove_depth = 2.0;
 
 	/*
@@ -147,15 +150,13 @@
 	Offsets are measured from the outside surfaces.
 	*/
 
-	inner_top_front_cutout_width = width - back_left - back_right;
+	inner_top_front_cutout_width = int_width;
 	inner_top_front_cutout_depth = top_groove_width;
 	inner_top_front_cutout_height = top - top_groove_depth;
-	inner_top_front_cutout_offset = top_groove_depth;
 
-	inner_side_front_cutout_height = height - inner_top_front_cutout_offset;
+	inner_side_front_cutout_height = height - top_groove_depth;
 	inner_side_front_cutout_width = front_side - groove_depth;
-	inner_side_front_cutout_depth = groove_width_extra;
-	inner_side_front_cutout_offset = groove_depth;
+	inner_side_front_cutout_depth = groove_width_overlap;
 
 	/*
 	The back cavity is the indented part at the bottom of the back of the
@@ -201,7 +202,7 @@
 	*/
 
 	edge_connector_cutout_front_offset = 1.0;
-	edge_connector_cutout_front_depth = 1.0;
+	edge_connector_cutout_front_depth = front_back_overlap;
 	edge_connector_cutout_front_width = 15.0;
 
 	/*
@@ -466,28 +467,23 @@
 
 		/* Inner top cutout for the top and sides of the back portion. */
 
-		translate([0, -inner_top_front_cutout_depth / 2, height / 2 -
-			inner_top_front_cutout_offset -
-			inner_top_front_cutout_height / 2])
-			cube([inner_top_front_cutout_width,
-				inner_top_front_cutout_depth,
-				inner_top_front_cutout_height], center = true);
+		cube_at(inner_top_front_cutout_width,
+			inner_top_front_cutout_depth,
+			inner_top_front_cutout_height,
+			0, -1, 1,
+			0, 0, int_payload_upper_extent);
 
-		translate([width / 2 - inner_side_front_cutout_offset -
-			inner_side_front_cutout_width / 2,
-			-inner_side_front_cutout_depth / 2,
-			-inner_top_front_cutout_offset / 2])
-			cube([inner_side_front_cutout_width,
-				inner_side_front_cutout_depth,
-				inner_side_front_cutout_height], center = true);
+		cube_at(inner_side_front_cutout_width,
+			inner_side_front_cutout_depth,
+			inner_side_front_cutout_height,
+			1, -1, 0,
+			int_width / 2, 0, -inner_top_front_cutout_height);
 
-		translate([-width / 2 + inner_side_front_cutout_offset +
-			inner_side_front_cutout_width / 2,
-			-inner_side_front_cutout_depth / 2,
-			-inner_top_front_cutout_offset / 2])
-			cube([inner_side_front_cutout_width,
-				inner_side_front_cutout_depth,
-				inner_side_front_cutout_height], center = true);
+		cube_at(inner_side_front_cutout_width,
+			inner_side_front_cutout_depth,
+			inner_side_front_cutout_height,
+			-1, -1, 0,
+			-int_width / 2, 0, -inner_top_front_cutout_height);
 
 		/* Fillets to round off the edges. */
 
@@ -536,14 +532,19 @@
 
 			/* Back portion. */
 
-			translate([0, back_depth - back / 2, 0])
-				cube([width, back, height], center = true);
-			translate([-width / 2 + back_left / 2, back_depth / 2, 0])
-				cube([back_left, back_depth, height], center = true);
-			translate([width / 2 - back_right / 2, back_depth / 2, 0])
-				cube([back_right, back_depth, height], center = true);
-			translate([0, back_depth / 2, height / 2 - top / 2])
-				cube([width, back_depth, top], center = true);
+			cube_at(width, back, height,
+				0, 1, 0,
+				0, int_back_depth, 0);
+			cube_at(back_left, back_depth + groove_width_extra, height,
+				-1, 1, 0,
+				-int_width / 2, -groove_width_extra, 0);
+			cube_at(back_right, back_depth + groove_width_extra, height,
+				1, 1, 0,
+				int_width / 2, -groove_width_extra, 0);
+			cube_at(width, back_depth + groove_width_extra, top,
+				0, 1, 1,
+				0, -groove_width_extra, int_payload_upper_extent);
+
 			difference() {
 
 				/* Floor of cartridge. */
@@ -594,26 +595,25 @@
 
 			/* Left groove. */
 
-			translate([-width / 2 + groove_depth / 2, groove_width / 2, 0])
-				cube([groove_depth, groove_width, height],
-					center = true);
+			cube_at(groove_depth, groove_width, height,
+				1, 1, 0,
+				-width / 2, -groove_width_extra, 0);
 
 			/* Right groove. */
 
-			translate([width / 2 - groove_depth / 2, groove_width / 2, 0])
-				cube([groove_depth, groove_width, height],
-					center = true);
+			cube_at(groove_depth, groove_width, height,
+				-1, 1, 0,
+				width / 2, -groove_width_extra, 0);
 
 			/* Top grooves. */
 
-			translate([0, groove_width / 2, height / 2 - groove_depth / 2])
-				cube([width, groove_width, groove_depth],
-					center = true);
+			cube_at(width, groove_width, groove_depth,
+				0, 1, -1,
+				0, -groove_width_extra, height / 2);
 
-			translate([0, top_groove_width / 2,
-				height / 2 - top_groove_depth / 2])
-				cube([width, top_groove_width, top_groove_depth],
-					center = true);
+			cube_at(width, top_groove_width, top_groove_depth,
+				0, 1, -1,
+				0, -groove_width_extra, height / 2);
 		}
 
 		/* Back cavity. */