add alignment sleeves for Hypercube 300

parametric_bracket.scad

@@ -6,19 +6,22 @@
 
 nominal_extrusion_width=20; 
 screw_diameter=5;
-gap=0.4; // adjust for your process
+gap=0.4; // adjust for a snug fit
 thickness=2.8; 
 
 // uncomment one of the following to render
 
 //corner_bracket();
 //t_bracket();
-double_t_bracket();
+//double_t_bracket();
+alignment_sleeves(); // for Hypercube 300 assembly
+//alignment_sleeve(60); // test for fit
 
 // other constants needed later
 
 tw=(nominal_extrusion_width+gap+2*thickness); // total width
 iw=(nominal_extrusion_width+gap+thickness)/2; // dimension from center of cube to center of hole
+sleeve_gap=gap+.2; // looser fit for alignment sleeves
 
 // top-level modules
 
@@ -92,8 +95,29 @@ module double_t_bracket()
 		brace();
 }
 
+module alignment_sleeves()
+{
+	alignment_sleeve(140);
+	translate([1.5*tw,0,0])
+		alignment_sleeve(155);
+}
+
 // lower-level modules
 
+module alignment_sleeve(length)
+{
+	// frame tools:
+	// 140 mm (center-to-center) between corner and T
+	// 155 mm (center-to-floor) under double-T
+
+	linear_extrude(length-tw-(nominal_extrusion_width/2))
+	difference()
+	{
+		square(nominal_extrusion_width+2*sleeve_gap+2*thickness, true);
+		square(nominal_extrusion_width+2*sleeve_gap, true);
+	}
+}
+
 module brace() // a pair of braces
 {
 	d=tw/2-4;