# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1389399154 -3600
# Node ID 71fe803717c1bbe9157f5e716d64242b15ed65f5
# Parent  830b2306de4718d36bd6e043a9e11b9d504ac96c
Changed the fillet module to add a margin of subtractable material around the
cylinder void; removed the extra length of subtractable material; made the
rounding offset the same as the radius.

diff -r 830b2306de47 -r 71fe803717c1 cartridge.scad
--- a/cartridge.scad	Sat Jan 11 00:52:30 2014 +0100
+++ b/cartridge.scad	Sat Jan 11 01:12:34 2014 +0100
@@ -2,10 +2,18 @@
 {
 	$fn = 50;
 
+	/* Rounding/fillet radius and additional margin of subtracted
+	material. The additional margin helps avoid geometry
+	problems. */
+
+	rr = 1;
+	ro = rr;
+	extra = 0.1;
+
 	module fillet(r, h) {
 		translate([0, 0, -h/2])
 			difference() {
-				cube([r, r, h]);
+				cube([r + extra, r + extra, h]);
 				cylinder(r = r, h = h);
 			}
 	}
@@ -22,10 +30,12 @@
 	front_label_height = 46.0;
 	front_label_depth = 1.0;
 	front_label_offset_from_bottom = 19.5;
+
 	top_label_width = front_label_width;
 	top_label_height = 11.5;
 	top_label_depth = front_label_depth;
 	top_label_offset_from_front = 2.5;
+
 	groove_depth = 1.0;
 
 	/* Side thicknesses. */
@@ -36,14 +46,6 @@
 	left = 2;
 	right = 2;
 
-	/* Rounding/fillet offset, radius and additional length.
-	The radius needs to be slightly larger than the offset
-	in order to avoid geometry problems. */
-
-	ro = 1;
-	rr = 1.01;
-	extra = 0;
-
 	difference() {
 
 		/* The cartridge surfaces. */
@@ -110,34 +112,34 @@
 			translate([-width / 2 + ro, 0, height / 2 - ro])
 				rotate([0, 0, 180])
 					rotate([90, 0, 0])
-						fillet(rr, depth + extra);
+						fillet(rr, depth);
 			translate([width / 2 - ro, 0, height / 2 - ro])
 				rotate([90, 0, 0])
-					fillet(rr, depth + extra);
+					fillet(rr, depth);
 		
 			/* Top back and front rounding. */
 		
 			translate([0, depth / 2 - ro, height / 2 - ro])
 				rotate([0, -90, 0])
-					fillet(rr, width + extra);
+					fillet(rr, width);
 			translate([0, -depth / 2 + ro, height / 2 - ro])
 				rotate([0, 0, 180])
 					rotate([0, -90, 0])
-						fillet(rr, width + extra);
+						fillet(rr, width);
 		
 			/* Edge rounding. */
 		
 			translate([width / 2 - ro, depth / 2 - ro, 0])
-				fillet(rr, height + extra);
+				fillet(rr, height);
 			translate([-width / 2 + ro, depth / 2 - ro, 0])
 				rotate([0, 0, 90])
-					fillet(rr, height + extra);
+					fillet(rr, height);
 			translate([-width / 2 + ro, -depth / 2 + ro, 0])
 				rotate([0, 0, 180])
-					fillet(rr, height + extra);
+					fillet(rr, height);
 			translate([width / 2 - ro, -depth / 2 + ro, 0])
 				rotate([0, 0, 270])
-					fillet(rr, height + extra);
+					fillet(rr, height);
 		}
 	}
 }