CNC Light Painting: First Attempt

backwards "J" light paintingAfter buying a Canon T2i camera a few months ago, I’ve been really excited to play around with different exposure settings and possibly some time-lapse photography.  The first trick that I’ve tried is something called “light painting.”  How this works is that your camera is held still and a light is moved around with the shutter open.  With the lens open it captures this light wherever it moves in the frame.  Alternatively, the camera can be moved around a light.

The photo to the right was made by moving the camera, but my idea was do light painting by moving the light.  As with making stencils for a bleach t-shirt, I don’t necessarily feel I have that much artistic skill, but I do own something that allows me to fake it, my CNC router.  The idea that I had was to attach a light to the X and Z axis and allow it to either be controlled manually or run a Gcode program that I generated.

The first three pictures above are some preliminary results using my ZTW 7 x 12 CNC router.  The first is a “green man” stick figure that was done with Gcode (you can barely make it out), but the other two are done by jogging what would normally be the X and Z axis.  As described in an earlier post, I’ve flipped these axes using my Mach3 control software, so the up and down motion now acts as the Y axis and the X axis is the same, moving the spindle left and right.

You can see the setup in the lower two pictures.  What I did is attached a LED flashlight to the spindle with a neodymium magnet (harvested from a hard drive disassembled for clocks).  Two green post-it notes were then attached to the light with a rubber band to diffuse it so it wasn’t too bright for the camera.

light painted pac man in green

…And that’s how you make a neon green pac-man!

Once this was done, the camera was either set to a 30 second exposure (the longest the T2i camera will allow – see page 84 for long exposure shooting in the T2i manual) while the router was manually jogged around, or some Gcode was executed and the “bulb” was hit until it was done.  I was pleased with these results, but several improvements needed to be made in order to really make this a cool project.  This included being able to selectively shut off the light and making light path a bit smaller since the Z (or now Y) range of my router is only around 2 inches.  I’ve also purchased a remote trigger so that I can open the bulb and keep it from shaking.  Be sure to check back or subscribe to see the results as I get this process perfected!


  1. Swap the Y and Z Axes on a CNC router with Mach3 | JCOPRO.NET - pingback on February 2, 2012 at 6:50 pm

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