add bearings to y-carriages and draw belts with proper length

lib/bearing_idler.scad

     }
 }
 
-module bearing_spacer(h = spacer_height, add_dia = 0) {
+module bearing_spacer(h = spacer_height, add_dia = 0, remove_dia = 0, enclose = false, enclose_size_add = 0) {
     $fn = 30;
+    siz = bearing_inner + spacer_size_add + add_dia;
     difference() {
-        cylinder(d = bearing_inner + spacer_size_add + add_dia, h = h);
+        hull() {
+            if (enclose) {
+                translate([-siz / 2, -(siz + enclose_size_add) / 2, 0])
+                    cube([siz, siz + enclose_size_add, 1]);
+            }
+            cylinder(d = siz, h = h);
+        }
         translate([0, 0, -1])
-            cylinder(d = bearing_inner + dia_off, h = h + 2);
+            cylinder(d = bearing_inner + dia_off - remove_dia, h = h + 2);
     }
 }
 

lib/linear_bearing.scad

 x_rail_hole_off = 5;
 x_rail_block_len = (y_carriage_length - x_rail_cutout_y) / 2;
 
+draw_y_carriage = false;
+draw_rail_len = 100;
+
+idler_a_blue = [  19,               15,  5.5];
+idler_a_red  = [  19, x_rail_dist + 15, 12.5];
+idler_b_blue = [30.3, x_rail_dist + 15, 12.5];
+idler_b_red  = [30.3,               15,  5.5];
+
 module lm8uu() {
     $fn = 15;
     difference() {
     }
 }
 
-// TODO add cable tie lm8uu mounting
+// TODO add cable tie canal for lm8uu mounting
 
 module generate_spacer(pos) {
     color("green")
     translate([pos[0], pos[1], -0.5])
-        bearing_spacer(pos[2] + 0.5 + ((idler_outer_height - bearing_height) / 2), 2);
+        bearing_spacer(pos[2] + 0.5 + ((idler_outer_height - bearing_height) / 2), 2, 1, true, 3);
 }
 
 module y_carriage(idler_a = [0, 0, 0], idler_b = [0, 0, 0]) {
     
     // idlers for the corexy belts
     translate([0, 0, y_carriage_wall]) {
-        translate(idler_a)
-            bearing_idler();
-        
-        translate(idler_b)
-            bearing_idler();
+        if (!draw_y_carriage) {
+            translate(idler_a)
+                bearing_idler();
+            
+            translate(idler_b)
+                bearing_idler();
+        }
         
         generate_spacer(idler_a);
         generate_spacer(idler_b);
     }
 }
 
-draw_y_carriage = false;
-draw_rail_len = 100;
-
 if (draw_y_carriage) {
     translate([(lm8uu_outer + lm8uu_dia_add) / 2 + y_carriage_rail_support, 0, 0])
     rotate([-90, 0, 0]) {
             cylinder(d = lm8uu_inner, h = draw_rail_len);
     }
 
-    y_carriage([15, 15, 10], [10, 65, 2]);
+    y_carriage(idler_a_blue, idler_b_blue);
 
     translate([(2 * y_carriage_width + y_carriage_block_width) + draw_rail_len -5, y_carriage_length, 0])
         rotate([0, 0, 180])
-        y_carriage([15, 15, 10], [10, 65, 2]);
+        y_carriage(idler_a_red, idler_b_red);
 }

xyRepRap.scad

 rail_mount_dist = 12;
 y_carriage_pos = 175;
 
-idler_a_blue = [  19, 15,  5.5];
-idler_a_red  = [  19, 65, 12.5];
-idler_b_blue = [30.3, 65, 12.5];
-idler_b_red  = [30.3, 15,  5.5];
-
 module rail(length) {
     cylinder(d = rail_dia, h = length);
     echo(rail_dia=rail_dia, rail_len=length);
         color("blue")
         translate([nema17_size / 2, nema17_size / 2 + 6.5, nema17_mount_wall + 1])
         rotate([0, 0, 180])
-            gt2_belt(200);
+            gt2_belt(outer_length - (5 * slot) - y_carriage_pos);
         color("blue")
         translate([-outer_length + (3 * slot) + 10 + nema17_size / 2, nema17_size / 2 - 6.5, nema17_mount_wall + 1])
             gt2_belt(outer_length - (3 * slot) - 10);
         rotate([0, 0, 180])
             gt2_belt(outer_length - (3 * slot) - 10);
         color("red")
-        translate([-200 + nema17_size / 2, nema17_size / 2 - 6.5, nema17_mount_wall + 8])
-            gt2_belt(200);
+        translate([nema17_size / 2 - (outer_length - (5 * slot) - y_carriage_pos), nema17_size / 2 - 6.5, nema17_mount_wall + 8])
+            gt2_belt(outer_length - (5 * slot) - y_carriage_pos);
     }
     
     // long back belts
     color("blue")
     translate([outer_width - slot - 15, slot + 10, outer_height - 7])
         rotate([0, 0, 90])
-        gt2_belt(200);
+        gt2_belt(y_carriage_pos + 10);
     
     // red belt on blue side
     color("red")
-    translate([slot + 15, slot + 209, outer_height - 14])
+    translate([slot + 15, slot + 19 + y_carriage_pos, outer_height - 14])
         rotate([0, 0, -90])
-        gt2_belt(200);
+        gt2_belt(y_carriage_pos + 10);
     
     // idler on blue side
     translate([slot + bearing_mount_width + 15, 0, outer_height - slot])