Microwave Oven Converted Into UV Chamber for Resin 3D Prints
Stijn Coenen converted an old microwave oven into a UV curing chamber for his resin 3D prints.
When compared to FFF (Fused-Filament Fabrication) 3D printing, resin 3D printing offers far better print quality. Resin 3D printers are much better at producing fine details in models and make layer lines almost invisible. But resin 3D printing also has some downsides. The resin itself is toxic and requires care to handle properly. Printed objects needs to be washed in alcohol and then exposed to strong UV light in order to cure completely. You can place those objects in direct sunlight for curing, but UV curing chambers are more convenient. But those are expensive, which is why Stijn Coenen converted an old microwave oven into a UV curing chamber for his resin 3D prints.
UV curing chambers are ideal for people who don't have free time during daylight hours, don't have a safe outdoor location to place 3D prints, or live in regions where consistent sunlight is uncommon. You can buy a UV curing chamber for as little as $60, but they increase dramatically in price as their size increases. Coenen figured a microwave oven would be perfect for the job, since they're dirt cheap when purchased used and have spacious interiors, turntables, and timers. He just needed to add some UV LEDs and a custom controller.
Coenen found that his donor microwave had a driver board that contained a PIC16C65B microcontroller. That meant that he could replace the microcontroller instead of designing a new driver board. He replaced the PIC16C65B with a PIC16F877A microcontroller that contained his new firmware. Coenen did have to perform a great deal of reverse-engineering to get the microwave's controls and four-digit seven-segment display working. But after doing so, he was able to take advantage of those to control the UV curing process.
A string of UV LEDs are mounted to the interior of the microwave and the turntable remains functional. Whenever he wants to cure a print, Coenen can place the part inside of the microwave, set the dial to the appropriate time, and then press start. It's as easy as heating up a frozen burrito!