My reprap setup involves a (mostly) Ecksbot mounted to a plywood base with an overhead spool holder. Due to how the filament feeds, it rubs against the top rail of my machine as it prints. This causes scuffing of the filament and plastic dust to fall on the print surface. I remedied this by putting a piece of plastic corrugated wire loom on this threaded rod, which frankly drives me crazy to hear the filament skipping/clicking against it while printing. Thought about wrapping it with tape or using a piece of hose instead, then it came to me...print as-is (7.8mm inner diameter, 229mm length) or modify OpenSCAD .scad file to taste. Make sure your heatbed is scorching hot and that your first layer gets pressed on good, this thing loves to curl!