First Z-Carriage iteration finished.

lib/linear_bearing.scad

 lm8uu_outer = 15;
 lm8uu_inner = 8;
 lm8uu_height = 24;
+lm8luu_height = 45;
 
 x_rail_dist = 70;
 
     }
 }
 
+module lm8luu() {
+    $fn = 15;
+    difference() {
+        cylinder(d = lm8uu_outer, h = lm8luu_height);
+        translate([0, 0, -1])
+            cylinder(d = lm8uu_inner, h = lm8luu_height + 2);
+    }
+}
+
 module lm8uu_cable_tie() {
     difference() {
         union() {

xyRepRap.scad

 show_z_motion = true;
 
 show_heatbed_frame = true;
-show_heatbed = true;
+show_heatbed = false;
 
 show_xy_motion = true;
 show_x_carriage = false;
-show_belts = false;
+show_belts = true;
 
 echo(print_x=heatbed_width, print_y=heatbed_length);
 echo(frame_x=outer_width, frame_y=outer_length, frame_z=outer_height);
 }
 
 z_carriage_wall = 10;
+z_carriage_bearing_dia_add = 0.4;
+z_carriage_cutout_width = 2;
+z_carriage_cabletie_cut_off = 5;
+z_carriage_use_cable_tie_mount = true;
 
 module z_carriage() {
+    echo(bed_screw_len=slot + z_carriage_wall + bed_z_dist + 10);
+    // bracket on t-slot bed frame
     color("green")
     translate([frame_off_x + bed_x_off - z_rail_x_off, frame_off_y + bed_y_off - rail_y_off, 0]) {
-        // bracket on long rail
-        translate([-z_carriage_wall, -z_carriage_wall, 0])
-            cube([z_carriage_wall, z_carriage_wall + (2 * slot), slot]);
+        // short side bracket on long rail
+        difference() {
+            translate([-z_carriage_wall, -z_carriage_wall, 0])
+                cube([z_carriage_wall, z_carriage_wall + (2 * slot), slot]);
+            
+            translate([-z_carriage_wall - 1, slot * 3 / 2, slot / 2])
+                rotate([0, 90, 0])
+                cylinder(d = 4.4, h = z_carriage_wall + 2);
+        }
+        
+        // short bottom bracket on long rail
+        difference() {
+            translate([-z_carriage_wall, -z_carriage_wall, -z_carriage_wall])
+                cube([slot + z_carriage_wall, 2 * slot + z_carriage_wall, z_carriage_wall]);
+        
+            translate([slot / 2, slot * 3 / 2, -z_carriage_wall - 1])
+                cylinder(d = 4.4, h = z_carriage_wall + 2);
         
-        // bracket on short rail
-        translate([0, -z_carriage_wall, 0])
-            cube([3 * slot, z_carriage_wall, slot]);
+            translate([slot / 2, slot / 2, -z_carriage_wall - 1])
+                cylinder(d = 4.4, h = z_carriage_wall + 2);
+        }
+        
+        // long side bracket on short rail
+        difference() {
+            translate([0, -z_carriage_wall, 0])
+                cube([3 * slot, z_carriage_wall, slot]);
+            
+            translate([slot * 5 / 2, -z_carriage_wall - 1, slot / 2])
+                rotate([-90, 0, 0])
+                cylinder(d = 4.4, h = z_carriage_wall + 2);
+        }
+        
+        // long bottom bracket on short rail
+        difference() {
+            translate([slot, -z_carriage_wall, -z_carriage_wall])
+                cube([2 * slot, slot + z_carriage_wall, z_carriage_wall]);
+            
+            translate([slot * 5 / 2, slot / 2, -z_carriage_wall - 1])
+                cylinder(d = 4.4, h = z_carriage_wall + 2);
+        }
     }
     
-    // TODO proper long bearings
-    color("magenta")
-    translate([0, 0, (slot - (2 * lm8uu_height + 1)) / 2]) {
-        %lm8uu();
-        %translate([0, 0, lm8uu_height + 1])
-            lm8uu();
+    // part around bearing
+    color("green")
+    translate([0, 0, -z_carriage_wall])
+    difference() {
+        hull() {
+            cylinder(d = lm8uu_outer + 10, h = slot + z_carriage_wall);
+            
+            translate([frame_off_x + bed_x_off - z_rail_x_off - z_carriage_wall, frame_off_y + bed_y_off - rail_y_off - z_carriage_wall, 0])
+                cube([slot + (2 * z_carriage_wall) + 20, 1, slot + z_carriage_wall]);
+        }
+        
+        // bearing cut out
+        translate([0, 0, -1])
+            cylinder(d = lm8uu_outer + z_carriage_bearing_dia_add, h = slot + z_carriage_wall + 2);
+        
+        if (z_carriage_use_cable_tie_mount) {
+            // cable-tie bearing mounts
+            for (i = [1 : 3])
+            translate([0, 0, ((z_carriage_wall + slot) * i / 4) - (cable_tie_width / 2)])
+                rotate([0, 0, 180])
+                lm8uu_cable_tie();
+            
+            // place for cable-tie to hold on to bearing
+            translate([-20, -40 - z_carriage_cabletie_cut_off, -1])
+                cube([40, 40, z_carriage_wall + slot + 2]);
+        } else {
+            // cut out to slide bearing in
+            translate([-z_carriage_cutout_width / 2, -20, -1])
+                cube([z_carriage_cutout_width, 20, slot + z_carriage_wall + 2]);
+        }
     }
+    
+    // linear bearing (long)
+    color("magenta")
+    translate([0, 0, (slot - z_carriage_wall - lm8luu_height) / 2])
+        %lm8luu();
 }
 
 module motion_z() {