MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
Filing the point where rack meets frame on the frame itself really helps with how smooth it is. I also suggest sanding down the rack, too (on the inside where they meet). This will make it a lot smoother if you’re using a not-very-precise 3D printer (Makergear M2/3, etc.)
P.S. I only said that Makergear M2/3 are not precise because they are a lot faster, but the Prusa i3 mk2.5 does the job perfectly.