diff --git a/lib/grommet.scad b/lib/grommet.scad
index 9477340..e00c3b1 100644
--- a/lib/grommet.scad
+++ b/lib/grommet.scad
@@ -16,7 +16,7 @@
     Code released under GPLv3: http://www.gnu.org/licenses/gpl.html
 
     grommet(face, style, od, id, wall, assembly, mask)
-    grommet_clip(style, od, id, height)
+    grommet_clip(style, od, id, wall)
 
 */
 
diff --git a/sbc_case_builder.scad b/sbc_case_builder.scad
index 93b76ad..4b5ef3f 100644
--- a/sbc_case_builder.scad
+++ b/sbc_case_builder.scad
@@ -1387,7 +1387,35 @@ if (view == "part") {
         if(case_design == "panel_nas" && (pcb_width > 100 || width > 101.6)) {
             rotate([270,0,0]) cableholder_spacer(hd_spacer-9.4);
         }
-        // ui access panel
+        if(case_design == "rack") {
+            // rear fan covers
+            for(r = [0:len(rack_bay_sbc)-1]) {
+                fan_offset = -75+(75-rear_fan_size)/2;
+                if(rack_bay_rear_fan[r] == true) {
+                    translate([-gap-wallthick-1+.125+75*(r+1)+fan_offset+8,0,0])
+                            fan_cover(rear_fan_size, wallthick, rear_cooling);
+                }
+            }
+            // rear grommets
+            for(r = [0:len(rack_bay_sbc)-1]) {
+                grommet_offset = -75+11;
+                if(rack_bay_rear_conduit[r] == true) {
+                    translate([0,0,0]) rotate([270,0,0]) difference() {
+                    translate([-gap-wallthick-1+.125+75*(r+1)+grommet_offset,0,0])
+                        grommet("bottom", "sleeve", 10, r+2, wallthick, false, [false,10,0,"default"]);
+                        translate([-gap-wallthick-1+.125+75*(r+1)+grommet_offset-10,-.125,-3]) cube([20,10,20]);
+                    }
+                    translate([0,20,0]) rotate([270,0,0]) difference() {
+                    translate([-gap-wallthick-1+.125+75*(r+1)+grommet_offset,0,0])
+                        grommet("bottom", "sleeve", 10, r+2, wallthick, false, [false,10,0,"default"]);
+                        translate([-gap-wallthick-1+.125+75*(r+1)+grommet_offset-10,-.125,-3]) cube([20,10,20]);
+                    }
+                    translate([-gap-wallthick-1+.125+75*(r+1)+grommet_offset,-20,0])
+                        grommet_clip("sleeve", 10, r+2, wallthick);
+                }
+            }
+        }
+       // ui access panel
         if(bottom_access_panel_enable == true) {
             if(access_panel_rotation == 0) {
                 translate([access_panel_location[0],-access_panel_location[1], 0]) rotate([0,0,access_panel_rotation]) 
diff --git a/tolerance_check.scad b/tolerance_check.scad
deleted file mode 100644
index f77e175..0000000
--- a/tolerance_check.scad
+++ /dev/null
@@ -1,20 +0,0 @@
-
-/* find correct tolerance and use for respective entry's data_1 value within sbc_case_builder.cfg */
-
-use <./sbc_case_builder_library.scad>;
-
-battery_tolerance = 0;
-speaker_tolerance = 0;
-volume_tolerance = 0;
-
-$fn = 90;
-
-translate([-33,0,0]) batt_holder(battery_tolerance);
-difference() {
-    translate([-17,-17,0]) cube([34,34,2]);
-    translate([0,0,-1]) cylinder(d=24, h=4);
-}
-translate([0,0,1.99]) boom_speaker_holder("friction",speaker_tolerance);
-
-translate([30,0,0]) boom_vring(volume_tolerance);
-