Introduction: Edge Lighting Effects With Acrylic
A while back I was working on a class project where we wanted to see what cool lighting effects we could get with acrylic. We were planning on making an iris door for the class, and we wanted to see what we could do with lighting that wouldn't involve having any electronics on the moving parts of the door. Edge lighting is a fairly common way to get some cool effects out of materials like acrylic and glass without having to put LED's all over the acrylic itself. I wanted to explore it a little further, so I wound up testing a few different effects, resulting in the final product above as a demonstration.
This isn't a step-by-step tutorial so much as how you can achieve some nifty effects, although I'll also explain how I made the project in the picture.
Just to clarify, this is not a working iris door. Our team decided decided to treat the lighting and the mechanics as two separate "experiments" so the focus of this model was only what it would look like, not how it would work. Before I made this one, I also made a working iris out of cardboard, so the leaf shape was based on that.
Step 1: Normal Edge Lighting
There's about a million tutorials on how to do edge lighting so I won't go too much into detail. Lighting the edge of a piece of clear material causes light to refract off of engraved parts, edges and bevels, which can be used to highlight design elements.
However, for our iris door, we weren't happy with the way traditional effects looked. We wanted to design it such that it would not be obvious that it was meant to light up, and for there to be a high contrast between the lit and unlit state. The idea was that right before the door opens, the light would turn on and outline or highlight the iris "leaves", creating more of a surprise effect. Etching the acrylic would give away the "surprise" (since it's very visible even when the light is off). The other problem with etching is that, at least on our laser cutter, it would have taken a very long time to etch the design, so there was a practical element as well.
Step 2: Beveling the Edges
The first effect I tried was sanding down the edge at an angle using a belt sander. That way, I still get the most of the brightness of the edge light, but from a front view. You can see that it came out really bright, even in a room that isn't completely dark. A steeper angle comes out brighter but it means there's less surface area visible when looking front on. The other thing is there's less of a "surprise" element since the sanded edges are translucent. I tried burned the beveled edges to get a shiny finish, but it wound up being much dimmer since it decreased the light refracted to the face.
Step 3: Painting the Acrylic
Painting the acrylic was one way I thought we might be able to better "hide" the engraved lines until the light was turned on. While it did better hide the engraved lines, it wound up dimming the light significantly. However, the effect on the angle edges was still quite bright.
Step 4: One-way Mirror
For this effect, I used a one-way mirror film applied to the acrylic so there would be a nearly opaque reflective surface. On the other side of the acrylic, I engraved channels to run a piece of electroluminescent wire (EL wire) through the acrylic. The idea was that when the light was off, the panel would simply appear to be shiny metal, and would only become visible when switch on.
The effect worked out okay, but it turns out the EL wire isn't as bright compared to the earlier beveled lighting effects. Additionally, because of the way one way mirrors work, the brighter the room the more opaque the surface appears (you can see in the photo it's still translucent), but then the hidden light must be brighter to compensate. With a brighter light (for instance, by embedding LED's instead of EL) and using less crappy one-way mirrors, this could be a really cool effect.
Step 5: Iris Door Model: Tools & Materials
To demonstrate what the beveled edge lighting effect would look like on the Iris Door, I made a quick model out of acrylic and foamcore. This is not actually a moving iris door - we decided to treat the lighting and the mechanics as two separate "experiments" so the focus of this model was only what it would look like, not how it would work. But, it's still pretty nifty, so I'm including the files if anyone wants to build something like this. Apologies for the lack of photographs - at the time I made it, my focus was not on documentation. However, if you're confused about assembly, feel free to send me a message and I'll try to clarify.
Tools & Materials:
LED strip & batteries
Foamcore, cardboard, or some similar material
Step 6: Iris Door Model: Fabrication & Assembly
The acrylic parts were all cut on a laser cutter using two different settings: a lower power for the engraved lines and a higher power to cut the outline. Every laser cutter is different, so you'll have to play around with the settings a bit to figure out how to engrave without cutting all the way through, and how to cut all the way through without burning the material (you may have to do more than one pass to cut all the way through). The edges were beveled on the belt sander.
There isn't too much more to the assembly - I built a shallow box out of some foamcore, lined the inner edges with LED's, and then put in an acrylic sheet with a circular cut out to hold the iris leaves in place (which I unfortunately can't find the file for!) that bolts to the ring on top, and a piece of foamcore on top of that to hide the inside of the box. Rather stupidly, I used foamcore for the back of the back, which you can't actually bolt to, the result being that there was nothing holding the whole thing in place from the back. So I'd definitely include a hard back so it doesn't fall apart!
Step 7: Lights On, Lights Off!
Ta-da! You can see that the beveled edges are still visible, but there's certainly a high contrast between the off and on state.
In the end, we wound up not even making a an iris door for the final project, but we still wound up using the effects of sanding and beveling acrylic for the door we did make!