Added printed lifter nut. Amazed that worked.

acme_screw.scad

@@ -0,0 +1,50 @@
+use <GDMUtils.scad>
+
+
+module acme_threaded_rod(
+	d=10.5,
+	l=100,
+	threading=3.175,
+	thread_depth=1
+) {
+	r = d/2;
+	twists = l/threading;
+	linear_extrude(
+		height=l,
+		convexity=20,
+		twist=-360*twists,
+		slices=12*twists,
+		center=true
+	) {
+		union() {
+			circle(r=r-thread_depth, center=true);
+			difference() {
+				circle(r=r, center=true);
+				translate([r/2, 0]) {
+					square([r, r*2], center=true);
+				}
+			}
+		}
+	}
+}
+
+
+module acme_threaded_nut(
+	od=17.4,
+	id=10.5,
+	h=10,
+	threading=3.175,
+	thread_depth=1,
+	slop=0.25
+) {
+	difference() {
+		cylinder(r=od/2/cos(30), h=h, center=true, $fn=6);
+		grid_of(za=[0,slop]) {
+			acme_threaded_rod(d=id, l=h+1, threading=threading, thread_depth=thread_depth+slop);
+		}
+	}
+}
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap
+