diff --git a/screw_gear.scad b/screw_gear.scad
new file mode 100644
index 0000000..49040b3
--- /dev/null
+++ b/screw_gear.scad
@@ -0,0 +1,32 @@
+screw_gear(8, 4, 2, 8, 18, 32);
+
+module screw_gear(outer_radius, inner_radius, thickness, thread_length, precision, total_length)
+{
+    linear_extrude(height=total_length, twist=360*total_length/thread_length, slices=360)
+    polygon(
+        points = screw_crosssection(outer_radius, inner_radius, thickness, thread_length, precision),
+        paths = [ range((precision+8)*2) ]
+    );
+}
+
+function screw_crosssection(outer_radius, inner_radius, thickness, thread_length, precision) =
+    concat(
+        [ for (x=[1 : 8]) polar(outer_radius, thickness*360/thread_length*x/8) ],
+        [ for (x=[1 : precision])
+            polar(
+                outer_radius-(outer_radius-inner_radius)*x/precision,
+                thickness*360/thread_length + x/precision*(180-(thickness*360/thread_length))
+            )
+        ],
+        [ for (x=[1 : 8]) polar(inner_radius, 180 + thickness*360/thread_length*x/8) ],
+        [ for (x=[1 : precision])
+            polar(
+                inner_radius+(outer_radius-inner_radius)*x/precision,
+                180 + thickness*360/thread_length + x/precision*(180-(thickness*360/thread_length))
+            )
+        ]
+    );
+
+function polar(r,theta) = r*[sin(theta), cos(theta)]; // convert polar to cartesian coordinates
+
+function range(n) = [ for(x = [0 : n-1]) x ];