Beautiful and Speedy CoreXY Light Painting
Fablab Kerala Fab Academy students turned to CoreXY kinematics when constructing this CNC light painting machine called Velichapaad.
Despite the obvious similarities, cameras are not eyes. Once you really absorb that fact, you can start coming up with imaginative photography techniques that don’t follow the same visual rules as own our physiology. Light painting is a great example, as it is distinct from persistence of vision. You can leave a camera’s shutter open as along as you want to achieve a desired effect. But even so, speed is handy. That’s why Fablab Kerala Fab Academy students turned to CoreXY kinematics when constructing this CNC light painting machine called Velichapaad.
Light painting is a long-exposure photography technique in which a light moves through a dark scene, leaving “trails” that can form shapes. You can achieve that by moving the light by hand, but attaching the light to a CNC motion system allows for precise control. When done well, CNC light paintings are extremely crisp. If you want to incorporate that with a human subject (or anything that isn’t still), you’re going to have to move the light very fast to keep the exposure time down and avoid blurring of the person. CoreXY kinematics have gained a reputation in the 3D printing community for being very fast, which is perfect for this scenario.
Several students worked on this project, each with their own specializations in different disciplines. Some students, for instance, worked on the electronics, while others worked on the mechanical design. That let them manage this ambitious project in a reasonable amount of time.
Mechanically, this is like the CoreXY gantry of a 3D printer turned on its side, so the XY plane is vertical. Really, it is a CoreXZ design with an overall size of 1500mm wide by 960mm tall. Instead of an extruder and hot end, the carriage moves a puck with a custom PCB containing seven WS2812B individually addressable RGB LEDs and an ESP32-C6 for control (wirelessly via ESP NOW). That unique puck can “paint” in any color and can vary the stroke width, too.
A Neoπ Wireless CNC Controller handles the primary motion system control. It is based on a NodeMCU ESP32 development board and has DRV8825 stepper drivers. There are two NEMA 17 stepper motors powered at 12V.
The results are pretty incredible. The lines are very crisp and the fast speed makes it possible to paint around people without them blurring.