Project Overview
Succinctly, our machine is a light 3D printer. We created a printhead that outputs light, and the mechanism which moves it around a three axis coordinate system with computer numerical control. The output is fleeting, and while our eyes cannot effectively process the information, a camera is able to record the it and create a representation of the ephemeral substance placed by the machine. Something that almost feels tangible. Objects made of light, set in space.
Drawing, or painting with light in this way is a practice that dates back to to the late 1880s when it was used primarily by researchers. The scientists/chronophotographers would attach lights to humans as they walked or moved around their workspace in order to study the way their bodies moved or make them more efficient workers. Artists took up the mantle after the researchers, notably Vilho Setälä began moving the camera instead of the lights to make drawings, and Man Ray began making drawing/painting in this way, both in the late 1920s and 30s.
CNC machines feel like a natural tool to create light paintings. Ideally they operate with greater precision and scale compared to human hands, and therefore might allow for more complex work to be made on shorter timeframes. We did not make the machine to express one idea, but a myriad. Each of the “prints” that we made, which we began to refer to as drawings at a certain point, are indicative of our varied interests and proclivities, and reflect what each member of our group wanted to use the tool for.
Process
The machine is made up of a 6′ x 6′ steel frame, with plasma cut ornament, that has been suspended 12′ in the air with threaded rod from a gantry which carries and defines the location for all the other components. Attached to the frame is the RAMBO board, which controls the machine, its power supply, 4 spools of string and 4 stepper motors (one for each corner). The steppers are connected to the board with standard RJ45 plugs and ethernet cables.
The printhead is a relatively simple box that allows us to carry an adafruit circuit playground and its AA batteries. It has attachment points at 4 corners, and the most recent iteration has a central tube for the strings to pass through. This was an attempt to mitigate turbulent movement during operation that was causing string to jump off the spool. We’re not sure how effective it was.
The printer uses the X, Y, Z, and E stepper controllers on the RAMBO board for the motors. The Marlin firmware on the board had to be reconfigured in order to remove software limits on the Z and E steppers, as well as to calibrate the steps/mm defined by the size of our spools. The motor moves 200 steps/revolution (400 microsteps/revolution). Theoretically, we divide the perimeter by 200 (steps/revolution) to get steps/mm. However, we realized there’s something weird after a few trials. We ended up calculating with microsteps/revolution. We finished the calibration with a one-millimeter margin of error. We controlled it with Pronterface. The machine has no limit switches and no auto homing mechanism, in order to tell it where it is we place it in the center of the printable area and take in the string with the motors until all four are taut. Then we give it a G92 command with the corresponding length of thread for all axis, that is determined in CAD.
To program the machine we wrote a Grasshopper definition that breaks up a curve into points, and then calculates the length that the string has to be from each motor to the printhead at every point. Formatting nodes in Grasshopper allow us to format those lengths as Gcode that the machine can understand. It felt like a strike of luck that this method of programming worked. The Rambo board handled the strange code very gracefully, pushing and pulling the string to bring the printhead to the designated points in space. The definition also adds pauses (G4) onto the second line, and the second to last line of code to make it easier to press and release the camera shutter at the right moment. Refer to the lightprinter_control.gh and .3dm files at the bottom of this page.
Files
download links
References
https://lightpaintingphotography.com/light-painting-history/