Ask Hackaday: Is PLA Biodegradable?

The most popular plastic for 3D printers is PLA – polylactic acid – a plastic that’s either derived from corn starch, inedible plant detritus, or sugar cane, depending where in the world it was manufactured. Being derived from natural materials, PLA is marketed as being biodegradable. You don’t need to worry about low-poly Pokemon and other plastic trinkets filling landfills when you’re printing with PLA, all these plastic baubles will return to the Earth from whence it came.

3D printers have been around for a few years now, and now objects printed in PLA have been around the sun a few times. A few of these objects have been completely forgotten. How’s that claim of being biodegradable holding up? The results are mixed, and as always, more data is needed.

A few weeks ago, [LazyGecko] found one of his first experiments in 3D printing. In 2012, he was experimenting with tie dying PLA prints by putting his prints in a jar filled with water and blue dye. This jar was then placed in the back of his cupboard and quickly forgotten. 3.5 years later, [LazyGecko] remembered his experiment. Absolutely nothing happened, save for a little bit of blue dye turning the print a pastel baby blue. The print looks and feels exactly like the day it came off the printer.

[LazyGecko]’s blog post was noticed by [Bill Waters], and he has one datum that points to PLA being biodegradable. In 2015, [Bill] printed a filter basket for his fish tank. The first filter basket worked well, but made a small design change a week later, printed out another, and put the first print in storage. He now has two nearly identical prints, one in constant use in a biologically interesting environment, the other sitting on a shelf for a year.

[Bill]’s inadvertent experiment is very close to the best possible experimental design to make the case for PLA biodegradability. The 3D printed filter basket in constant use for a year suffered significant breakdown, and the honeycomb walls are starting to crumble. The ‘inert’ printed filter basket looks like it just came off the build plate.

If that’s not confusing enough, [Bill] also has another print that has spent a year in a fish tank. This end cap for a filter spray bar didn’t see any degradation, despite being underwater in a biologically active environment. The environment is a little different from a filter basket, though; an aquarium filter is designed to break down organics.

To answer the question, ‘is PLA biodegradable,’ the most accurate answer is, ‘maybe’. Three data points in uncontrolled environments isn’t enough to draw any conclusions. There are, undoubtedly, more forgotten 3D prints out there, and more data to back up the claim of PLA being biodegradable.

This is where you come in. Do you have some forgotten prints out there? Your input is needed, the fruits of your labors are evidence, your prints might be decaying and we want to know about it below.

Be A Hero At Your Next Hackathon With A Foldable CNC

Be the hero at your next hackathon with this foldable cnc. When the line for the laser cutter is four teams deep, you’ll come out ahead. It might even be accurate enough to pop out a quick circuit board. Though, [wwwektor] just wanted a CNC that could be taken from storage and unfolded when needed. Sit it on a kitchen table and cut out some ornaments, or hang it from the front door to engrave the house’s address. Who needs injection molded chrome plated numbers anyway?

It’s based around tubular ways, much like other 3D printed CNCs we’ve covered. The design’s portable nature gives it an inherently unstable design. However, given the design goals, this is reasonable. It uses timing belts, steppers, and ball bearings for its movement. The way the frame sits on the table it should deal with most routing tasks without needing adjustment to stay in plane with the surface it’s set-on. As long as you don’t need square edges.

There’s a video of it in operation after the break. We love these forays into unique CNC designs. We never know what new idea we’ll see next.

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Kicking The Tires Before You Buy: 3d Printers

So you’re looking to buy your first 3D printer, and your index finger is quivering over that 300 US Dollar printer on Amazon.com. Stop! You’re about to have a bad time. 3D printing has come a long way, but most 3D printers are designed through witchcraft, legends, and tall tales rather than any rigorous engineering process. I would say most 3D printer designs are either just plain bad, or designed by a team of Chinese engineers applying all their ingenuity to cost cutting. There are a few that are well designed, and there is a comparatively higher price tag attached.

I’ll start by going through some of the myths and legends that show up in 3D printers. After that I’ll go through some of the common, mostly gimmick, features that typically hinder your printer’s ability, rather than adding any useful function. Next I’ll go onto the things that will actually make your printer better. Finally, I’ll add some special consideration if you’re a beginner buying your first printer.

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Good Vibrations in 3D-Printed Clay

An engineer with a 3D printer wants everything to be rigid and precise. Wobble induced by flex in the z-axis feedscrews, for instance, makes telltale wavy patterns in the surface that match exactly the screw pitch. Nobody likes those, right? Certainly not an engineer!

good_vibrations-shot0008_thumbnailBut one man’s surface irregularity is another man’s ornamentation. The details we have are sparse, but from looking at the video (also inlined below the break) it’s clear enough: [Olivier van Herpt] and [Ricky van Broekhoven] stuck a vibrating woofer underneath the print bed of their ceramic printer, and use it to intentionally ruin their smooth surface. And they do so to great artistic effect!

We’re not suggesting that you give up entirely on your calibrations, but we do appreciate a little out-of-the-box thinking from time to time. But then our internal engineer raises his head and we wonder if they’re linking the pitch of the woofer to the feed rate of the print head. Your thoughts in the comments?

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The OpenR/C Project

The Open RC Truggy that started it all.
The Open RC Truggy that started it all.

[Daniel Norée] started the OpenR/C project back in 2012 when he bought a Thing-O-Matic. In search of a project to test out his new printer, he set his sights on a remote controlled car, which as he put it,”… seemed like the perfect candidate, as it presents a lot of challenges with somewhat intricate moving parts along with the need for a certain level of precision and durability.

After releasing his second design, the OpenR/C Truggy, he realized a community was forming around this idea, and needed a place to communicate. So, he created a Google+ group. Today, the Truggy has been downloaded over 100,000 times and the Google group has over 5,000 members. It’s a very active community of RC and 3d printing enthusiasts who are testing the limits of what a 3d printer can do.

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A 3D Printed Jet Engine Appears to Function

[amazingdiyprojects] has been working on a 3D printable jet engine. You may remember seeing a 3D printed jet engine grace our front page back in October. That one was beautiful didn’t function. This one flips those values around. [amazingdiyprojects] seems to make a living from selling plans for his projects, so naturally most of the details of the build are hidden from us. But from what we can see in the video clips there are some really interesting solutions here.

Some of the parts appear to be hand-formed sheet metal. Others are vitamins like bearings and an electric starter. We really liked the starter mechanism, pressing in the motor to engage with a spline, or perhaps by friction, to give the starting rotation.

What really caught our attention was casting the hot parts of the printer in refractory cement using a 3D printed mold. It reminds us of the concrete lathes from World War 1. We wonder what other things could be built using this method? Flame nozzles for a foundry? A concrete tea-kettle. It’s pretty cool.

We’re interested to see how the jet engine performs and how others will improve on the concept. Video of it in action after the break.

UPDATE: [amazingdiyprojects] posted a video of the engine being disassembled.

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Take Your 3D Printing to the Next Dimension

In what is being hailed as the next great advancement in 3D printing, scientists have been able to get a 3D printed shape to change form when it is exposed to water, bringing 3D printing squarely into the realm of the fourth dimension. Although the only examples we’ve seen so far are with relatively flat prints (which arguably subtracts one “D” from the claim) the new procedure is one which is groundbreaking for the technology.

The process uses cellulose fibers which, when aligned in a particular way and exposed to water, swell in order to change shape. This is similar to how a bimetallic strip in a thermostat works, but they really took their inspiration from biological processes in plants that allow them to change shape according to environmental conditions. It’s hard to tell if this new method of printing will forever alter the landscape of 3D printing but, for now, it’s an interesting endeavor that will be worth watching. The video after the break shows a fast-motion print using the technique, followed by a demo of the print submersed in water.

We often see new technological advancements that use biology as a springboard for new ideas, and this one is no different. There have been building structures inspired by pinecones and this Processing hack inspired by squid. Biology is all around us, and any of it could be used for inspiration for your next project!

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