diff --git a/readme.md b/readme.md
index 669c9c7..74ede50 100644
--- a/readme.md
+++ b/readme.md
@@ -2940,7 +2940,7 @@ Machine screws and wood screws with various head styles.
 |:--- |:--- |
 | ```screw(type, length, hob_point = 0, nylon = false)``` | Draw specified screw, optionally hobbed or nylon |
 | ```screw_and_washer(type, length, star = false, penny = false)``` | Screw with a washer which can be standard or penny and an optional star washer on top |
-| ```screw_countersink(type)``` | Countersink shape |
+| ```screw_countersink(type, drilled = true)``` | Countersink shape |
 
 ![screws](tests/png/screws.png)
 
diff --git a/tests/png/mains_sockets.png b/tests/png/mains_sockets.png
index 5e1a950..889ab1a 100644
Binary files a/tests/png/mains_sockets.png and b/tests/png/mains_sockets.png differ
diff --git a/tests/png/socket_box.png b/tests/png/socket_box.png
index 4274a21..53d1296 100644
Binary files a/tests/png/socket_box.png and b/tests/png/socket_box.png differ
diff --git a/vitamins/mains_socket.scad b/vitamins/mains_socket.scad
index 36ab783..17882ed 100644
--- a/vitamins/mains_socket.scad
+++ b/vitamins/mains_socket.scad
@@ -116,7 +116,7 @@ module mains_socket(type) { //! Draw specified 13A socket
             cylinder(r = screw_clearance_radius(screw), h = 100, center = true);
 
             translate_z(height)
-                screw_countersink(screw);
+                screw_countersink(screw, drilled = false);
         }
     }
 }
diff --git a/vitamins/screw.scad b/vitamins/screw.scad
index 007b0df..ab8e0a1 100644
--- a/vitamins/screw.scad
+++ b/vitamins/screw.scad
@@ -247,14 +247,23 @@ module screw(type, length, hob_point = 0, nylon = false) { //! Draw specified sc
     }
 }
 
-module screw_countersink(type) { //! Countersink shape
+module screw_countersink(type, drilled = true) { //! Countersink shape
     head_type   = screw_head_type(type);
     head_rad    = screw_head_radius(type);
-    head_height = head_rad;
+    rad = screw_radius(type);
+    head_t = rad / 5;
+    head_height = head_rad + head_t;
 
     if(head_type == hs_cs || head_type == hs_cs_cap)
         translate_z(-head_height)
-             cylinder(h = head_height, r1 = 0, r2 = head_rad);
+            if(drilled)
+                cylinder(h = head_height, r1 = 0, r2 = head_rad + head_t);
+            else
+                intersection() {
+                    cylinder(h = head_height + eps, r1 = 0, r2 = head_rad + head_t);
+
+                    cylinder(h = head_height + eps, r = head_rad + eps);
+                }
 }
 
 module screw_and_washer(type, length, star = false, penny = false) { //! Screw with a washer which can be standard or penny and an optional star washer on top