diff --git a/libtest.png b/libtest.png
index d169c11..eeb7743 100644
Binary files a/libtest.png and b/libtest.png differ
diff --git a/libtest.scad b/libtest.scad
index 4a12c49..3d3d31a 100644
--- a/libtest.scad
+++ b/libtest.scad
@@ -225,7 +225,7 @@ inserts_y = 0;
 nuts_y = inserts_y + 20;
 washers_y = nuts_y + 120;
 screws_y = washers_y + 120;
-circlips_y = screws_y + 160;
+circlips_y = screws_y + 180;
 springs_y = circlips_y + 20;
 o_rings_y = springs_y;
 sealing_strip_y = springs_y + 20;
@@ -402,21 +402,21 @@ extrusions_y = panel_meters_y + 80;
 translate([x3, veroboard_y])
     veroboard_test();
 
-translate([x3 + 60, veroboard_y + 20])
+translate([x3 + 50, veroboard_y + 20])
     geared_steppers();
 
 translate([x3 + 160, ssrs_y])
     pcb_mounts();
 
-translate([x3 + 170, veroboard_y + 16])
+translate([x3 + 145, veroboard_y + 16])
     cameras();
 
+translate([x3 + 145, d_connectors_y - 10])
+    camera_housings();
+
 translate([x3, d_connectors_y])
     d_connectors();
 
-translate([x3 + 170, d_connectors_y - 10])
-    camera_housings();
-
 translate([x3, iecs_y])
     iecs();
 
diff --git a/readme.md b/readme.md
index a48dc59..f76fcf1 100644
--- a/readme.md
+++ b/readme.md
@@ -3484,6 +3484,7 @@ For an explanation of `screw_polysink()` see <https://hydraraptor.blogspot.com/2
 | `screw_radius(type)` | Nominal radius |
 | `screw_socket_af(type)` | Socket across flats |
 | `screw_socket_depth(type)` | Socket or slot depth |
+| `screw_thread_diameter(type)` | Thread diameter, if different from nominal diamter |
 | `screw_washer(type)` | Default washer |
 
 ### Functions
@@ -3526,12 +3527,14 @@ For an explanation of `screw_polysink()` see <https://hydraraptor.blogspot.com/2
 |   1 | `screw(M3_hex_screw, 10)` |  Screw M3 hex x 10mm |
 |   1 | `screw(M3_low_cap_screw, 10)` |  Screw M3 low cap x 10mm |
 |   1 | `screw(M3_pan_screw, 10)` |  Screw M3 pan x 10mm |
+|   1 | `screw(M3_shoulder_screw, 12)` |  Screw M3 shoulder x 12mm |
 |   1 | `screw(M4_cap_screw, 25)` |  Screw M4 cap x 25mm |
 |   1 | `screw(M4_cs_cap_screw, 25)` |  Screw M4 cs cap x 25mm |
 |   1 | `screw(M4_dome_screw, 25)` |  Screw M4 dome x 25mm |
 |   1 | `screw(M4_grub_screw, 8)` |  Screw M4 grub x  8mm |
 |   1 | `screw(M4_hex_screw, 30)` |  Screw M4 hex x 30mm |
 |   1 | `screw(M4_pan_screw, 30)` |  Screw M4 pan x 30mm |
+|   1 | `screw(M4_shoulder_screw, 16)` |  Screw M4 shoulder x 16mm |
 |   1 | `screw(M5_cap_screw, 30)` |  Screw M5 cap x 30mm |
 |   1 | `screw(M5_cs_cap_screw, 30)` |  Screw M5 cs cap x 30mm |
 |   1 | `screw(M5_dome_screw, 30)` |  Screw M5 dome x 30mm |
diff --git a/tests/png/screws.png b/tests/png/screws.png
index 856a400..a5f01f0 100644
Binary files a/tests/png/screws.png and b/tests/png/screws.png differ