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January 18, 2017

What I’ve learned so far about the magical world of 3D printing

A cynical person might comment that I have loved 3D printing for so long that it’s *very convenient* that such a cool technology is so important to the Curiosity Project. Admittedly, there’s a grain of truth in this. But my enthusiasm began during my PhD when I used toys to study children’s word learning (Twomey, Ranson & Horst, 2014, seeing as you asked). To understand how children learn words, we need to know how they process the language they hear, but also how they process the objects they attach that language to. We need to be able to control features of the stimuli we use in our studies, and 3D printing allows us to do this quickly, simply, cheaply, and most importantly, accurately. No more hot-gluing lentils to polystyrene for me! (That one was Horst & Twomey, 2013).

For any developmental psychologists interested in using 3D printing to make stimuli , here’s what I’ve learned so far. Note that I’m going to talk about my own experience with Makerbot – other 3D printers are available!

  • Cost:
    • 3D printers aren’t cheap, but they’re cheaper than the other equipment we use (eyetrackers anyone?). Our Makerbot Replicator+ cost around £2000. The filament is around £50 a spool and lasts for ages. Printing a toy-sized object costs pennies.
    • Makerbot software is free, as is SketchUp,a free 3D design package that’s very easy to learn
    • The printer comes with a free spool of filament. It’s grey, so good for models of Star Wars things, or British Members of Parliament.
  • Design:
    • I was terrified of having to do a degree in CAD to make my objects, but it can be very simple with SketchUp. It allows you to push and pull parts of your design, resize easily, look from all angles, copy and past elements… I love it because it makes me feel clever with minimal effort (unlike R). I’d recommend their online tutorials to get started.
    • Your 3D design needs to be a hollow, continuous surface to be printable, but it’s easy to accidentally leave disconnected edges or small holes in your design. SketchUp has a plugin called Solid Inspector. This invaluable tool highlights these holes (they’re sometimes almost invisible) so that you can fill them in.
    • Makerbot takes .stl files. SketchUp doesn’t automatically produce these, but you can download an .stl plugin, and export (rather than save) your file to .stl
    • Once you’ve made your .stl file, you have to import it into MakerBot Print. This free software lets you convert .stl files to .makerbot files, which you can then print on your lovely, shiny, whirring printer.
    • You can also download thousands of .stl files pre-made from Makerbot’s Thingiverse (http://www.thingiverse.com/). Careful what you search for, though – there’s no accounting for taste.
  • Printing
    • After you’ve unpacked your printer and had a sit down and a cup of tea to cope with the excitement, you’ll go through a set-up routine via the LCD screen on the front. Our printer isn’t networked, so we did this using the Makerbot Android app. Remember the Windows 95 printer test page? The Makerbot equivalent is a small plastic chain. I have never been so awestruck by something so… grey.
    • Once it’s set up, it’s as simple as putting your files on a USB and sticking the USB in the port. I was hugely surprised that it worked perfectly, first time. That never happens in science.
    • Printing takes a while. Six 3″ x 1.5″ x 1.5″ cuboid-ish shapes took a night. Bear this in mind if you think you’ll need something quickly.
    • Once your object is printed, remove the base plate and snap them off. It’ll have printed a “sacrifical base” (thank you to the eminent Barrie Usherwood, our departmental technician (genius wizard), for this excellent phrase). Snap this off too.
    • Now that you have your object, show it to all of your friends, take it to the pub, show your Dad at Christmas, take photos of it, inflict it on social media. You are the FUTURE.
  • Other notes
    • Entry-level 3D printers work by heating up a plastic filament and extruding (what a wonderful word) it in layers to build up a shape. Your finished object will have small ridges in it. If you want it to be perfectly smooth, you’ll have to paint it. Painting isn’t completely straightforward. For developmental work you need non-toxic paint, and because the plastic is ridged, it can seep and leave a feathery outline (you know, like Dot Cotton’s lipstick). I wouldn’t recommend trying to paint spots on a flat surface, for example. Painting a small surface (like the top of a protrusion) works much better.
    • If you design something with a large overhang, think about how you’re going to orient it before you print. Although Makerbot is clever, so far I haven’t managed to get it to deal well with big overhangs. For example, you might want to print a dog with a tail that sticks out. If you print the dog standing on its feet, you’ll find that the finished object has squiggly bits of filament underneath the tail, which have sagged before the filament has cooled sufficiently to be solid. You can use sandpaper to smooth these, but they’re part of the structure of the object, so you risk holes. Instead, you could orient the dog to lie on its side in Makerbot Print to minimise the dribbly bits. There may well be a better way around this, but at this early stage I’ve not needed to figure out why.

That’s it for now! I’d love to hear from anyone else with different ways of doing it.

IMPORTANT NOTE: My adventures in 3D printing would not be possible without the support of the ESRC: thank you! Perhaps more critically, they wouldn’t be possible without Barrie. Barrie: thank you for your help.