In the early days of hobbyist 3D printing, it was quite common for people to build their own 3D printers based on open source designs like those developed by the RepRap project. But those were usually cobbled together from less-than-ideal materials such as wood, and used inferior components like threaded rods instead of proper leadscrews. Consumer 3D printers quickly reached very affordable prices, and now there is little reason to build your own printer from scratch. But Frank Zhao wanted a printer more robust than anything on the market, and so he designed and built his own.
The performance and quality of a 3D printer is the result of many factors, but rigidity is arguably the most important. Any flexibility in the frame or linear movement drives of a 3D printer will result in poor quality prints. That is usually the cause of prominent layer lines and ghosting around features. A lot of tricks can be implemented to reduce those, such as smooth acceleration and deceleration of each axis. But the simplest and most effective way to prevent those issues is to build a heavy, sturdy frame.
That’s why Zhao’s Hephaestus 3D printer design has a box frame made from aluminum T-slot extrusion and water jet-cut aluminum plates. That’s heavier and more bulky than most commercial 3D printer designs, but it’s also much more rigid. That rigidity ensures that the Hephaestus 3D printer is capable of producing high-quality prints, even at fast speeds. The linear movement components are all fairly standard, but are precision-machined for smooth motion.
The only parts of the 3D printer that weren’t custom-made by Zhao are the Duet controller and the E3D Titan hot end. Even the extruder was designed by Zhao. That has a unique flex drive system that moves the extruder motor off of the carriage, ultimately reducing the moving weight and further improving print quality. It combines the benefits of traditional direct-drive extruders and Bowden extruders. The result is a completely custom 3D printer that’s capable of producing parts with fantastic detail and surface finish. Unfortunately, Zhao doesn’t plan on publishing his design files, as this printer would be impractical for most people to build.