Added a screw generator script, WIP

screw.scad

@@ -0,0 +1,35 @@
+/* common screw parameter
+length
+pitch = length/rotations: the distance between the turns of the thread
+outside_diameter
+inner_diameter: thickness of the shaft
+*/
+
+module helix(pitch, length){
+
+}
+
+module auger(pitch, length, outside_diameter, inner_diameter) {
+    rotations = length/pitch;
+	union() {
+		linear_extrude(height=length, center=false, convexity=10, twist=360*rotations, slices=100, $fn=1000)
+			polygon(points=[[10,10],[100,1],[100,-1],[10,-10]], paths=[[0,1,2,3]]);
+		cylinder(h=length, r=20);
+	}
+}
+
+translate([300, 0, 0]) auger(100, 300);
+
+
+module ball_groove(pitch, rotations, diameter, bearing_radius=10) {
+    rotations = length/pitch;
+    linear_extrude(height = 10, center = false, convexity = 10, twist = 360, $fn = 1000)
+        translate([diameter, 0, 0])
+        circle(r = bearing_radius);
+}
+
+ball_groove(100, 300, 10);
+
+module ball_screw(pitch, length, bearing_radius=2) {
+
+}