I’ve gotten a few questions about lithophanes since I posted the last entry on printing challenges, so here’s a few tips to get you started. For detailed history and information not only on 3d printing lithophanes, but also creating them with UV cured pigment inks and even laser engraving, check out Hacking the Digital Print, due out in February 2015. We even have instructions on how to make a full-color version of a 3d printed lithophane – it’s pretty cool.
Lithophanes are an art form designed to use transmitted light to generate an image. The density of material determines how light or dark a particular portion of the image is – thicker material appears darker. Traditionally these were created by carving porcelain or wax, a subtractive technique. Of all the modern approaches, laser engraving most closely matches this traditional form.
Additive techniques, like UV printing and 3D printing aren’t ‘officially’ lithophanes by the traditional definition (litho=stone after all), but the term has become somewhat generic and it’s what’s used. I’ve done a number of these, and they generate more conversation than almost any other print I hand to someone. Without a light behind one, they just look like a slab of plastic, but when lifted to the lamp, they become an incredibly detailed photograph.
You can use any color filament to create your lithophane, but if you’re going to use the full-color technique in Hacking the Digital Print, you should choose white or transluscent. I find that low-warping filaments like HIPS work the best, but have had good luck with PLA and even ABS.
There’s a number of ways to create an STL file to print. The most common is the lithophane customizer on Thingiverse, which produces decent, but not very detailed, lithophanes. My go-to tool is Photo2Mesh from www.ransen.com. It’s not very expensive, and the quality of the mesh produced is hands-down the best of any software I’ve tried.
When selecting an image for a lithophane, remember, you’re relying on the brain to fill in the missing information, so faces or other large objects that are easily recognizable work the best – think a lawnmower, rather than a grass lawn (the high random detail in the lawn just doesn’t work very well). I shoot with a D800, so initially tried using full-resolution files, but ended up with unprintable massive STL files (I killed Makerbot Desktop after waiting more than 30 minutes to slice those). After experimenting, I’ve found that 150 dpi works the best for high-quality prints, and a jpg is perfectly fine. You’ll want to make sure that you have decent contrast in the image, and the import it into Photo2Mesh.
The base thickness and Z height are the two settings I primarily change. I’ve found that there’s no need to print very thick lithophanes, so a base thickness of 1 and a z-height of 2.5 work just fine for most images. Make sure you check the ‘invert’ option in order to get the right effect we’re looking for. Oh, and if you want to print a cylindrical version, slow down the printer to make sure the overhangs don’t sag.
Just as an aside, I use VMWare Fusion to run windows software like this on my mac – I’ve used it for years, and find it works really well (no need for bootcamp for most things).
After you export the STL file, the next choice is your slicer. For the book I printed the lithophanes on a MakerBot 5th Generation Replicator in PLA and on a Lulzbot TAZ4 in ABS and HIPS. As in my previous post, you really need a glass bed to print these, and a heated bed really makes a difference. I used a raft on the Makerbot, but didn’t on the Lulzbot – skipping the raft makes the back of the lithophane smoother, and easier to the colorization process on (less sanding and prep).
For the Makerbot you’ll need to use Makerbot desktop to slice the image – just choose the high-quality profile, and set the infill to 100%. For the Lulzbot, you’ve got a few different options.
I’ve used Slic3r, Cura, and Simplify3D for the lithophanes. All work pretty well, but my primary choice is Simplify3D because it has an option to do concentric fill. This seems to eliminate much of the linen effect you can get with rectilinear fill. Since we’re working with 100% fill, you’ll want to make sure your machine is setup to flow the right amount of material, and is leveled properly too – and I mean dead-level. If you have flow problems, you may get intermittent lines printing, and you’ll see those striations in the final print.
After printing, let the print cool completely before trying to remove it from the bed. I tried blowing a fan across the surface to speed it up, but ended up with a warped and stuck lithophane. Just letting it cool naturally seems to be the best. These can be difficult to remove, so be careful to not damage PET or PEI tape (using a glue stick provides a release adhesive that helps get it off). Blue tape is, well, sacrificial in my mind – I just peel the whole thing off the build place when doing one of these.
After your print is done, check the book for more ideas on hand screens and techniques to do a full color version as part of a final presentation.