diff --git a/readme.md b/readme.md
index 4792f19..260a7a4 100644
--- a/readme.md
+++ b/readme.md
@@ -616,16 +616,11 @@ Can draw three styles: solid, open frame and open frame with screw bosses.
 | ```fan_thickness(type)``` | Thickness of the frame |
 | ```fan_width(type)``` | Width of square |
 
-### Functions
-| Function | Description |
-|:--- |:--- |
-| ```fan_screw_length(type, thickness)``` | Screw length required |
-
 ### Modules
 | Module | Description |
 |:--- |:--- |
 | ```fan(type)``` | Draw specified fan, origin in the centre |
-| ```fan_assembly(type, thickness, include_fan = true, screw = false)``` | Fan with its fasteners |
+| ```fan_assembly(type, thickness, include_fan = true, screw = false, full_depth = false)``` | Fan with its fasteners |
 | ```fan_hole_positions(type, z = undef)``` | Position children at the screw hole positions |
 | ```fan_holes(type, poly = false, screws = true, h = 100)``` | Make all the holes for the fan, or just the aperture if ```screws``` is false. Set ```poly``` true for poly_holes. |
 
@@ -652,9 +647,9 @@ Can draw three styles: solid, open frame and open frame with screw bosses.
 |  20 | ```screw(M4_dome_screw, 16)``` |  Screw M4 dome x 16mm |
 |   4 | ```screw(M4_dome_screw, 25)``` |  Screw M4 dome x 25mm |
 |   4 | ```screw(M4_dome_screw, 30)``` |  Screw M4 dome x 30mm |
-|   4 | ```washer(M2p5_washer)``` |  Washer  M2.5 x 5.9mm x 0.5mm |
-|   8 | ```washer(M3_washer)``` |  Washer  M3 x 7mm x 0.5mm |
-|  28 | ```washer(M4_washer)``` |  Washer  M4 x 9mm x 0.8mm |
+|   8 | ```washer(M2p5_washer)``` |  Washer  M2.5 x 5.9mm x 0.5mm |
+|  12 | ```washer(M3_washer)``` |  Washer  M3 x 7mm x 0.5mm |
+|  32 | ```washer(M4_washer)``` |  Washer  M4 x 9mm x 0.8mm |
 
 
 <a href="#top">Top</a>
@@ -1683,6 +1678,7 @@ PCBs and perfboard with optional components. The shape can be a rectangle with o
 ### Functions
 | Function | Description |
 |:--- |:--- |
+| ```pcb_component_position(type, name)``` | Return x y position of specified component |
 | ```pcb_coord(type, p)``` | Convert offsets from the edge to coordinates relative to the centre |
 | ```pcb_screw(type, cap = hs_cap)``` | Mounting screw type |
 
diff --git a/tests/png/fans.png b/tests/png/fans.png
index c0572fa..152826c 100644
Binary files a/tests/png/fans.png and b/tests/png/fans.png differ
diff --git a/vitamins/fan.scad b/vitamins/fan.scad
index 70bf01d..89de9c3 100644
--- a/vitamins/fan.scad
+++ b/vitamins/fan.scad
@@ -147,11 +147,16 @@ module fan_holes(type, poly = false, screws = true, h = 100) { //! Make all the
     }
 }
 
-function nut_and_washer_thickness(screw, nyloc) = washer_thickness(screw_washer(screw)) + nut_thickness(screw_nut(screw), nyloc);
-function fan_screw_depth(type) = fan_boss_d(type) ? fan_depth(type) : fan_thickness(type);
-function fan_screw_length(type, thickness) = screw_longer_than(thickness + fan_screw_depth(type) + nut_and_washer_thickness(fan_screw(type), true)); //! Screw length required
+function fan_screw_depth(type, full_depth = false) = fan_boss_d(type) || full_depth ? fan_depth(type) : fan_thickness(type);
 
-module fan_assembly(type, thickness, include_fan = true, screw = false) { //! Fan with its fasteners
+function fan_screw_length(type, thickness, full_depth = false) =
+    let(depth = fan_screw_depth(type, full_depth),
+        washers = depth == fan_depth(type) ? 2 : 1,
+        washer = screw_washer(fan_screw(type)),
+        nut = screw_nut(fan_screw(type)))
+            screw_longer_than(thickness + depth + washer_thickness(washer) * washers + nut_thickness(nut, true)); //! Screw length required
+
+module fan_assembly(type, thickness, include_fan = true, screw = false, full_depth = false) { //! Fan with its fasteners
     translate_z(-fan_depth(type) / 2) {
         if(include_fan)
             fan(type);
@@ -160,11 +165,14 @@ module fan_assembly(type, thickness, include_fan = true, screw = false) { //! Fa
         nut = screw_nut(Screw);
         fan_hole_positions(type) {
             translate_z(thickness)
-                screw_and_washer(Screw, fan_screw_length(type, thickness));
+                screw_and_washer(Screw, fan_screw_length(type, thickness, full_depth));
 
-            translate_z(include_fan ? -fan_screw_depth(type) : 0)
+            translate_z(include_fan ? -fan_screw_depth(type, full_depth) : 0)
                 vflip()
-                    nut(nut, true);
+                    if(fan_screw_depth(type, full_depth) == fan_depth(type))
+                        nut_and_washer(nut, true);
+                    else
+                        nut(nut, true);
         }
      }
 }