diff --git a/katzenklappe.scad b/katzenklappe.scad
index 9365f72..ac6f161 100644
--- a/katzenklappe.scad
+++ b/katzenklappe.scad
@@ -19,6 +19,10 @@ space = bearing_outer_dia; // space between plexy glass sheets
 // calculations
 rad = (space+2*plexy_t)/2;
 sheet_h = tunnel_h-2*seal-rad;
+h0 = stopper_w/2;
+h1 = guide_h-gap-10;
+h2 = 10+gap+h0;
+h3 = bearing_h/2+gap;
 
 // colors
 plexy = [0.4,0.6,1,0.6];
@@ -65,7 +69,7 @@ module screw(){
 module sheets(){
     difference(){
         union(){
-            translate([0,(space+plexy_t)/2,-sheet_h/2])cube([tunnel_w-2*seal,plexy_t,sheet_h],true);
+            translate([0,(plexy_t+space)/2,-sheet_h/2])cube([tunnel_w-2*seal,plexy_t,sheet_h],true);
             translate([0, (plexy_t+space)/-2,-sheet_h/2])cube([tunnel_w-2*seal,plexy_t,sheet_h],true);
         }
         hull(){
@@ -77,18 +81,16 @@ module sheets(){
 }
 
 module guide(){
-    a = guide_h-gap-10;
-    b = 10+gap+stopper_w/2;
-    translate([b, 0,a/2-sheet_h])cube([20,space,a],true);
-    translate([-b, 0,a/2-sheet_h])cube([20,space,a],true);
+
+    translate([h2, 0,h1/2-sheet_h])cube([20,space,h1],true);
+    translate([-h2, 0,h1/2-sheet_h])cube([20,space,h1],true);
 
 }
 
 module bearing_case(){
-    a = bearing_h/2+gap;
-    rotate(ry) cylinder(d=bearing_inner_dia-gap,h=a);
-    translate([a/2+stopper_w/4,0,stopper_h/2]) cube([stopper_w/2-a,space-2*gap,stopper_h],true);
-    translate([(stopper_w/2+5)/2,0,stopper_h-5]) cube([stopper_w/2+5,space-2*gap,10],true);
+    rotate(ry) cylinder(d=bearing_inner_dia-gap,h=h3);
+    translate([h3/2+stopper_w/4,0,stopper_h/2]) cube([h0-h3,space-2*gap,stopper_h],true);
+    translate([(h0+5)/2,0,stopper_h-5]) cube([h0+5,space-2*gap,10],true);
 }
 
 module bearing(){
@@ -109,7 +111,6 @@ module stopper(){
 }
 
 module flap(){
-    b = 10+gap+stopper_w/2;
     translate(z*(sheet_h-rad)/2) rotate(x*angle) {
         difference(){
             rotate(y*90) cylinder(d=2*rad,h=tunnel_w-2*seal,center=true);
@@ -122,10 +123,10 @@ module flap(){
                 sheets();
                 guide();
             }
-            translate([b,0,5-sheet_h])screw();
-            translate([b,0,guide_h-15-gap-sheet_h])screw();
-            translate([-b,0,5-sheet_h])screw();
-            translate([-b,0,guide_h-15-gap-sheet_h])screw();
+            translate([h2,0,5-sheet_h])screw();
+            translate([h2,0,guide_h-15-gap-sheet_h])screw();
+            translate([-h2,0,5-sheet_h])screw();
+            translate([-h2,0,guide_h-15-gap-sheet_h])screw();
             translate([tunnel_w/ 4,0,rad/-2])screw();
             translate([tunnel_w/-4,0,rad/-2])screw();
         }