# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1460375803 -7200
# Node ID b223381924337c9f5ca5a3fa9902aa1a7cf4d72f
# Parent  9bd1e34cd4424a661b711ac17bafc166af7746fe
Added the alternative approach of removing the back cavity entirely in the
connector section.

diff -r 9bd1e34cd442 -r b22338192433 cartridge.scad
--- a/cartridge.scad	Mon Apr 11 12:52:23 2016 +0200
+++ b/cartridge.scad	Mon Apr 11 13:56:43 2016 +0200
@@ -36,6 +36,12 @@
 	FRONT_LABEL_INSET = 0; TOP_LABEL_INSET = 0;
 	GROOVE = 0; ROUND_EDGES = 0; ROUND_CONNECTING_EDGES = 0;
 
+	To retain the back connecting piece instead, change the above to...
+
+	BACK_CONNECTOR_SECTION = 1;
+	EXTERNAL_BACK_CAVITY = 0;
+	EXTERNAL_BACK_CUTOUT = 1;
+
 	Leave all options enabled for more capable 3D printers.
 	*/
 
@@ -43,7 +49,10 @@
 	BACK_CONNECTOR_SECTION = 1;
 
 	/* A necessary exterior cavity to let the cartridge fit inside the slot. */
-	BACK_CAVITY = 1;
+	EXTERNAL_BACK_CAVITY = 1;
+
+	/* An alternative cutout to let the cartridge fit inside the slot. */
+	EXTERNAL_BACK_CUTOUT = 0;
 
 	/* Optional insets for labels. */
 	FRONT_LABEL_INSET = 1;
@@ -1082,9 +1091,9 @@
 
 					if (BACK_CONNECTOR_SECTION) {
 
-						/* Back cavity. */
+						/* Provide an external cavity. */
 
-						if (BACK_CAVITY)
+						if (EXTERNAL_BACK_CAVITY)
 							intersection() {
 
 								/* From the bottom upwards. */
@@ -1117,7 +1126,26 @@
 												]);
 							}
 
-						/* Inner back cavities. */
+						/* Or remove the back section entirely. */
+
+						else if (EXTERNAL_BACK_CUTOUT)
+							translate([0, back_depth, lower_extent])
+								linear_extrude(height = back_cavity_height)
+									translate([int_connector_left_extent, 0, 0])
+										polygon([
+											[back_cavity_offset_from_inner_left, 0],
+											[inner_back_slope_min_offset,
+												-connector_back + inner_back_slope_depth],
+											[inner_back_slope_min_offset, -connector_back],
+											[int_connector_width - inner_back_slope_min_offset,
+												-connector_back],
+											[int_connector_width - inner_back_slope_min_offset,
+												-connector_back + inner_back_slope_depth],
+											[back_cavity_offset_from_inner_left +
+												back_cavity_width, 0]
+											]);
+
+						/* Inner back cavities making the back thinner at the sides. */
 
 						translate([0, int_connector_back_depth, lower_extent])
 							linear_extrude(height = int_connector_height)
@@ -1141,7 +1169,7 @@
 										[0, inner_back_slope_depth]
 										]);
 
-						/* Inner back edge cavity. */
+						/* Inner back edge cavity, tapering the bottom edge. */
 
 						translate([inner_back_edge_width / 2,
 							int_connector_back_depth + inner_back_edge_depth, lower_extent])