provided 3D printable files and a detailed walkthrough for upgrading the Z-axis of a Prusa i3 RepRap 3D printer with a lead screw. Not for the first time and certainly not for the last, it would seem that a round of applause is due for aninanimate rod. Many cheap and cheerful DIY 3D printers, such as the Prusa i3 and other RepRap machines, use a threaded rod for their z-axis. The threaded rod is a cheap piece of equipment, but many users—Daniel included—have encountered irresolvable problems when using the oblong piece of metal. Use of a threaded rod as the z-axis of a 3D printer is standard for many budget machines, but notable problems include backlash and wobble, which can be eliminated with the use of a lead screw. Threaded rod is, after all, not made to be used as a precise positioning tool. It is built to fasten and to remain stationary at all times. Threaded rods can often be slightly bent, and they get dirty very quickly. “After a year of printing, it can clearly be seen that threaded rods are not meant for this kind of application,” Daniel explains in his blog post. “The rod…squeaks pretty loudly during movement and its threads get full of black goo that consists of dust, oil and metal shavings from the friction with the nut.” To improve performance on his Prusa i3 3D printer, “A lead screw is much more rigid, it’s very hard so it doesn’t bend, it has a very smooth surface and its shape is specifically designed for moving inside a nut.” To facilitate the upgrade, had to replace all of the z-axis mounts on his 3D printer. He designed and 3D printed these new pieces in PLA, at a 0.2mm layer height at 200°C. All of his 3D printed parts can be downloaded for free on the project’s Thingiverse page. upgraded z-axis has eliminated the squeaking and wobbling produced by the threaded rod. But is the upgrade worthwhile? The debate between threaded rod advocates and lead screw supporters goes back years. Generally, defenders of the humble threaded rod have argued that the cost of a lead screw eclipses the small improvement offered, and that proper maintenance of a threaded rod can lead to similarly high performance. Lead screw backers typically point to the improved accuracy and precision of their preferred device. Where do you stand on the eternal rod debate?