Ever since the iSchool purchased four 3D printers last fall, I have been experimenting with and learning all about 3D printing. I’ve come across several really awesome ways in which people innovate with this technology, but one stood out to me as a really awesome project for a Christmas present (and also a really cool way to show off what I am learning at school to my family).
Lithophanes are 3D pictures that come to life when you shine a light through them. 3D modeling software has gotten really good at taking pictures and creating 3D models where the dark areas of the picture are printed higher than the light areas. This creates a lithophane because the higher printed areas do not let as much light through as the lower printed areas, creating enough contrast to see a picture. Knowing this, I decided I wanted to create a lamp that would showcase a few 3D printed lithophanes.
This meant I would have to:
- Design a lamp to hold the lithophanes
- Figure out a lighting source
- Find a few pictures that I wanted to print
- Alter the chosen pictures to fit my lamp design
- 3D print the pictures
- 3D print the lamp
- Wire the lighting
I will cover each of these steps individually. If anyone is hoping to emulate my project, here are the supplies needed:
- LED strip (this is the exact one I used)
- 3D printer
- 3D printing slicer software (the printers at the iSchool use Cura)
- Printer filament for the lithophanes (I used white, but theoretically other colors should work)
- Printer filament for the lamp (I used brown, but the lamp could be the same color as the lithophanes if one so chooses)
- Hot glue gun
- Photo editing software (I used GIMP)
- Sand paper
- Dremel tool
Designing the Lamp – 3D Modeling
For the model designing, I used Blender, a free 3D modeling software available on PC, Mac and Linux (yay open source!). I wanted this lamp to hold several sizes of photo, but all photos would need to have a standard width to allow for in-line stacking. I chose to make the standard width of my lithophanes 75 mm because that seemed like an appropriate scale for a lamp. I made the lamp hight twice as tall as it is wide (150mm). To fit 75 x 150 mm of lithophane, the dimensions of the lamp had to be a little more than that with a millimeter or two for wiggle room.
In the center of the lamp I made a roughly cylindrical pillar to wrap the LEDs around. The base of the lamp is hollow to hold the electronics that come with the LEDs. There are also holes for the power, receiver, and lights. I assumed the lithophanes would probably push the arms out a bit, so I designed the lid to hold the arms in place. I was going to finish with the lid, but decided to print a separate base to hide the open bottom.
I put this design up on Thingiverse.
Finding a Light Source
My vision for this lamp is essentially a box that has lithophanes for sides. A light source for this project will need to be an irregular shape. By irregular, I simply mean not just one source of light from a bulb. It will also need to be compact and not too prone to heating up, otherwise the 3D printing plastic could melt. After a little searching I found that LED light strips fit the bill, and after a little Amazon browsing I found this kit. I was only looking for standard white LED’s but after finding these RGB color changing LEDs I couldn’t not get them.
Finding the Right Pictures
Picking out pictures is mostly easy, but there are a few things to consider. All pictures must be scaleable to a ratio of 75x[blank], where blank is the height. Heights can be anything, as long as you find other pictures that together make the heights all add up to 150.
For convenience, I limited myself to 3 sizes of photo. 75 x 50, 75 x 75, and 75 x 100. My intent with this is to have two sides of the lamp be made of two 75 x 75 squares (4 squares total), and have two sides hold one 75 x 50 and one 75 x 100 picture (2 landscape and 2 portraits, making 8 pictures total).
Tweaking the Pictures
To optimize these pictures for my lamp, I edited them to have a black “frame”. I am doing my photo editing in GIMP, another free open source application available for PC, Mac and Linux. When the lithophanes 3D print, black will be printed to maximum thickness, which will make the black frame act like an actual frame. This will also guarantee that all of the lithophanes are the exact same depth, which will make sliding them into the arms of the lamp easier. Other than that tweaking is strictly aesthetic. It is useful to convert photos to grayscale to see a rough approximation of what the lithophane will look like. Bumping up the contrast helps in photos that are hard to make out.
Printing the Pictures
This part should have been fairly straightforward, but I ran into trouble wrestling with my 3D printer and finding the optimum settings for this new white filament. The picture below on the left is of the prints that didn’t come out right, or that I didn’t let finish because it wasn’t what I wanted. Once I found the right settings for my filament, printing went smoothly. Final lithophane prints are show below on the right.
To print a picture as a lithophane, open Cura (or other slicer program with lithophane feature) and either drag the picture you want to print into the window, or click load and select your picture. A window will pop up to choose settings for the lithophane. Settings do not have to be exactly what I chose, but they do have to be consistent with the other pictures you print. Because I designed the lamp to hold 75mm width pictures, width must always be 75. Once all the settings are in place, hit “ok” and tune the printer settings to optimize for filament type and print time.
Printing the Lamp
I started printing the body of my lamp with a travel speed of 200mm/second, which proved to be a mistake. At that speed, the belt skipped while printing the base of the lamp (see photos of the faulty alignment below). I crossed my fingers, hoping that that was just a fluke, and let the print continue. There were a few minor issues, but things were going smoothly until the arms were halfway finished printing when the belt skipped again. Since the arms have to be exact in order to hold the pictures, I killed the print there and called it a day.
Instead of scrapping the frame print and starting from scratch, I decided to try to salvage my lamp. I measured the arms that did print, and printed lengths of arms/center pole that didn’t. I then used a little acetone to melt the plastic at the points I wanted to join. I did this by simply applying acetone with a paint brush. Once the plastic is a little melted, joining the pieces was as simple as pushing them together and making sure they line up. (Acetone can be used for finishing prints as well. Painting it on can leave surfaces shiny and can hide layer lines. You could also use an acetone vapor to create an even and smooth surface.) Once the acetone evaporated fully, my lamp was fully assembled and just as sturdy as a print that wasn’t printed in two parts.
I was very happy that the pictures fit the arms. One problem I was running into was that the arms were bending out a bit and not hugging the lithophanes as tightly as I wanted (see below left). The lamp lid held those in though. Printing the lid went very smoothly and I was very pleased with how snug it fit (below middle). The base printed without any problems as well (below right).
Wiring the Lighting
Wiring the lighting was actually pretty easy. The holes for my receiver and power cord were a little too small so I used a Dremel tool and some sand paper to widen them enough to fit their respective wires. That is a problem I fixed on the model I uploaded to Thingiverse so it shouldn’t be an issue for anybody wanting to recreate this.
The hole for the lights was sized perfectly and I was able to get the LED strip wrapped around the lamp’s center pole with little to no hassle. The LED strip comes with an adhesive on its back side, but it doesn’t work very well. I ended up using hot glue to secure the LED strip and its cord, and that seems to have solved the bad adhesive problem. If I were to do this project over again I would probably design a bracket on the lamp to hold the LED strip at the top an bottom of the lamp just so I could avoid needing hot glue.
Assembled and Update
In the picture below on right I tried flipping some of the lithophanes so that they cannot be seen at all without the light on. They still work, but are far less detailed. I am sure that with a little tweaking to how I print them I could make that work better, but that is a project for another time.
Unfortunately, I forgot to take final product pictures before I wrapped this for Christmas, but it looks great and I am very happy with how it turned out. On Christmas morning the lamp was a hit. It was left on for over an hour while we opened presents. Unfortunately, being on that long melted the hot glue holding the LED strip to the center post.
The lid closes off the airflow to the lights and creates a small oven. This is definitely not ideal as I would like this to be the type of lamp that can be left on overnight without worry. As a temporary fix I added a layer of super glue, which should at the very least not melt. This is far from a permanent solution seeing as heating up enough to melt hot glue means approaching a temperature that threatens the stability of the ABS plastic. I need to see if I can do something to keep it from heating up in the first place, but for now leaving the lid off seems to mostly remedy the situation.