Wednesday, July 24, 2013

Emissions from a 3D printer - are they dangerous?

Like many educators working with kids and 3D printing, my ears perked up when I read this blog post title, Could 3D Printing be Dangerous?

Reading further, I learned that a group had measured total ultrafine particle (UFP) concentrations resulting from the operating of a common desktop 3D printers inside "a commercial office space in Chicago."  (Here's a third article, if you are interested.)

This image was, by far, the "scariest."  You can see that the PLA printers were barely a blip, but when those ABS printers were turned on, the number concentration of particles spiked.

As I glanced from my computer screen to my Makerbot, I had some questions:  What does this scale mean?  Are the UFPs actually harmful, or just present?  Are these particles equal to or worse than the particulate from a busy outdoor street?  Or cooking indoors? In fact, the second article writes, "These emission rates are on about the same order as several other devices and activities known to emit UFPs, such as cooking on a gas or electric stove, burning scented candles, operating laser printers, or even burning a cigarette!"

Many of these questions remain to be answered.

In the journal article itself, the authors state. "One important limitation to this study is that we have no information about the chemical constituents of the UFPs emitted from either type of 3D printer, although condensation of synthetic organic vapors from the thermoplastic feedstocks are likely a large contributor (Morawska et al., 2009). In addition to large differences in emission rates observed between PLA- and ABS-based 3D printers, there may also be differences in toxicity because of differences in chemical composition."

But, some salient points came out of this article:

1.  Ventilation.  "Therefore, results herein suggest that caution should be used when operating these 3D printing instruments inside unvented or unfiltered indoor environments due to their large emissions of UFPs."  How ventilated is ventilated?  Is a classroom big enough?  How about if we keep the doors and windows open?    Can schools afford a ventilation system?  Can schools not afford to have one?

2.  ABS vs. PLA (<< link added later) - both plastics have their pros and cons, but the article did make me think more carefully about my purchase of a third classroom 3D printer.  We ended up going with the Printrbot Jr v2 (link added), which is intended for PLA.

3.  It is important to stay within the recommendations of the manufacturer.  Our Makerbot, for example, is set to 220 degrees Celsius for ABS.  I've heard (see point #4) that ABS particulate is not toxic unless it is heated above a certain temperature, often quoted to me at 260 degrees C.

Many people also complain of getting headaches from ABS printing, but in the 2.5 years I've been working with kids, I have yet to hear of a student making such a complaint.  (And trust me, they can complain about smells: isopropanol, sulfur...)  I am in the room the most, and ABS "fumes" have never bothered me, but I am not particularly sensitive.  Conventional wisdom states that PLA is friendlier, and smells a little like waffles when it's being melted.  (My room often smells a lot like 7th graders, so it can be hard to smell the waffles...) :)

4.  I need to do more research.

I'll keep you posted.

Wednesday, July 3, 2013

Cortex: The 3D Printed Cast

Many people have experienced the traditional plaster cast - bulky, smelly, and itchy.  Well, Jake Evill, a recent design graduate from the Victoria University of Wellington in New Zealand, is set to change all that. (pun intended)

Evill has developed he prototype idea for Cortex, a revolutionary cast that is "fully ventilated, super light, shower friendly, hygienic, recyclable and stylish."

Here are the basic steps involved in creating a Cortex cast:

Based on the scan data, computer software would determine the perfect design for your cast, providing more dense support in the area of the fracture.  Once on, the cast would close with fasteners that would later be removed using specialized tools, must like how plaster casts require a trip to the doctor for removal now.   The resulting cast would be about 3 millimeters thick and weigh less than 500 grams.

trabecular bone -
click image to see original location
Evill began his process with noticing that traditional casts are heavy and gross.  Then he looked around to see what kinds of alternatives existed.  He found none.  So, he decided to work on his own idea.  Evill began by researching the structure of bones, and was inspired by the trabecular (or spongy, or cancellous) bone that makes up the inside of long bones, providing structure without a lot of solid weight.  “It was this honeycomb structure that inspired the Cortex pattern because, as usual, nature has the best answers,” he said. “This natural shape embodied the qualities of being strong whilst light just like the bone it is protecting within.” (from Wired)

According to Wired, Evill used an Xbox Kinect to scan the arm for his prototype (Perhaps the same $80 scanner I was able to play with at this meetup event last weekend?  Lots of tutorials on how to do this: 12, 3, or you can search tutorials on YouTube.) After cleaning up the scan, he sent the file off to Shapeways to be printed.

Some critics (what's wrong with you people?) complain that a 3D printed cast would take too long to print.
"At the moment, 3D printing of the cast takes around three hours whereas a plaster cast is three to nine minutes, but requires 24-72 hours to be fully set," says the designer. "With the improvement of 3D printing, we could see a big reduction in the time it takes to print in the future."

It's important to realize that the Cortex cast is only a concept now, but may easily be incorporated as the medical field gets more and more involved with 3D printing.

You can check out Evill's other work on his website, including Pola, a conceptual design for a virtual camera that create and then pushes (physical) images out from the side of your head.  I kid you not.

You can read more about Cortex at Wired & dezeen.