Pulleys and belts now T2.5 on kit version.

JHead now attached by three screws and washers.
New extruder breakout PCB.
Lots of instruction manual improvements from user feedback.

scad/conf/utils.scad

@@ -117,10 +117,11 @@ module sector(r, a, h, , center = true) {
 }
 
 module tube(or, ir, h, center = true) {
-    difference() {
-        cylinder(r = or, h = h,    center = center);
-        cylinder(r = ir, h = h + 1, center = center);
-    }
+    linear_extrude(height = h, center = center, convexity = 5)
+        difference() {
+            circle(or);
+            circle(ir);
+        }
 }
 
 //