Common Enzyme Breaks Down PLA Fast

The global issue of plastic waste has prompted scientists to seek innovative solutions for recycling. Single-use plastics, notorious for their environmental impact, require new methods for efficient and sustainable management. For some common plastics, though, salvation could be at hand, with researchers identifying a common enzyme that can be used to break them down fast.

Researchers at King’s College London have discovered an enzyme used in laundry detergents that can break down PLA plastics within 24 hours, using a little heat as an aid. Normally, this is achieved via composting methods that take weeks or months. This method transforms the plastics back into their original chemical components, offering a rapid and eco-friendly recycling process. The monomers can then be reused for manufacturing new plastic items.

One wonders if this could also be used in another way – perhaps in a multimaterial printer, allowing PLA to be used for supports and then broken down. It’s probably not that necessary, given other degradable materials exist, but it’s something to think about.

This project is a significant leap forward in recycling technology, showcasing the potential for enzymes to revolutionize how we handle plastic waste. It could also be a great way to recycle all those errant deformed Pikachus that keep ending up in your hackerspace’s 3D-printing waste basket. In any case, plastic waste is a problem the world needs to solve, and quickly, because it’s not going anywhere any time soon. Video after the break.

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Lessons Learned From A High-Voltage Power Supply

When you set out to build a 60,000-volt power supply and find out that it “only” delivers a measly 50,000 volts, you naturally have to dive in and see where things can be improved. And boy, did [Advanced Tinkering] find some things to improve.

First things first: if you haven’t seen [Advanced]’s first pass at a high-voltage supply, you should go check that out. We really liked the design of that one, and were particularly impressed with the attention to detail, all of which seemed to be wisely geared to the safe operation of the supply. But as it turns out, the margin of safety in the original design wasn’t as good as it could be. Of most concern was the need to physically touch the supply to control it, an obvious problem should something go wrong anywhere along the HV path, which includes a ZVS-driven flyback and an epoxy-potted Crockcroft-Walton voltage multiplier.

To make things a little more hands-off, [AT] added a pneumatically actuated switch to the supply, along with some indicator lights to help prevent him from leaving the supply powered up. He also reworked the low-voltage DC supply section, replacing a fixed-voltage supply and a DC-DC converter with a variable DC supply. This had the side benefit of providing a little bit more voltage to the ZVS driver, which goosed up the HV output a bit. The biggest change, though, was to the potted part of the HV section, which showed signs of arcing to the chassis. It turns out that even at 100% infill, 3D printed PLA isn’t a great choice for HV projects; more epoxy was the answer to that problem. Along with rewinding the primary on the flyback transformer, the power supply not only hit the 60-kV spec, but even went a little past that — and all without any of that pesky arcing.

We thought [Advanced Tinkering]’s first pass on this build was pretty slick, but we’re glad to see that it’s even better now. And we’re still keen to see how this supply will be put to use; honestly, the brief teaser at the end of the video wasn’t much help in guessing what it could be.

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Lessons In Printer Poop Recycling

The fundamental problem with multi-color 3D printing using a single hotend is that they poop an awful lot. Every time they change filaments, they’ve got to purge the single nozzle, which results in a huge number of technicolor “purge poops” which on some machines are even ejected out a chute at the back of the printer. The jokes practically write themselves.

What’s not a joke, though, is the sheer mass of plastic waste this can produce. [Stefan] from CNC Kitchen managed to generate over a kilo of printer poop for a 500-gram multi-color print. So he set about looking for ways to turn printer poops back into filament, with interesting results. The tests are based around a commercial lab-scale filament extruder, a 3Devo Composer, but should apply to almost any filament extruder, even the homebrew ones. A few process tips quickly became evident. First, purge poops are too big and stringy (ick) to feed directly into a filament extruder, so shredding was necessary.

Second, everything needs to be very clean — no cross-contamination with plastics other than PLA, no metal bits in the chopped-up plastic bits, and most importantly, no water contamination. [Stefan]’s first batch of recycled filament came from purge poops that had been sitting around a while, and sucked a lot of water vapor from the air. A treatment in a heated vacuum chamber seems to help, but what worked best was using purge poops hot and fresh from a print run. Again, ick.

[Stefan] eventually got a process down that produced decent, usable filament that would jam the printer or result in poor print quality. It even had a pretty nice color, which of course is totally dependent on the mix of colors you start with. Granted, not everyone has access to a fancy filament extruder like his, so this may not be practical for everyone, but it at least shows that there’s a path to reducing the waste stream from any printer, especially multi-material ones.

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Using 5V Programmable Logic Here In The 2020s

Do you speak GAL? [Peterzieba] does, and has pulled together a collection of documents and tools so that you can too. There’s a dividing line in electronic engineering education, between those who were taught about FPGAs, and those who weren’t. Blurring that line slightly is gate array logic (GAL). These devices were a preceursor to the FPGA, with a much simpler structure, and usually in those days UV-erasable in the same manner as an EPROM. And oddly enough, they, or at least their successor compatible parts, are still available, and as handy DIP devices that talk to 5 volt logic.

The guide goes into detail about the parts, the terminology surrounding them, and the CUPL language which raises a few memories for us. There are several possible workflows, including for those not faint of heart, the possibility of writing a fusemap by hand. We’re impressed by that one.

If these devices interest you, our colleague Bil Herd wrote a two-part guide (part one, and part two) which should answer your questions.

Thanks [Bjonnh] for the tip!

Featured image: “Commodore Amiga 1000 – sub board – Texas Instruments PAL16L8ACN-0126” by Raimond Spekking

Repairing A Home Injection Molding Machine

When [Michael] over at the Teaching Tech YouTube channel bought a hobby injection molding machine a long time ago, one of the plans he had with it was to use it for grinding up waste bits of PLA filament for injection molding. Since the machine was bought from a US shop and [Michael] is based in Australia it required some modifications to adapt it to the local 220+ VAC mains, followed by adding a PID temperature controller and a small compressor to provide the compressed air rather than from a large shop compressor.

Although [Michael] had discussed using the machine for PLA with the seller to confirm that this would work, a user error meant that the now defective unit had been sitting idly for many years, until recently.

Since the machine had been gathering dust and rust in the garage, fixing the machine up took a complete teardown to remove corrosion and resolve other issues. After this the original fault was identified, which turned out to be a shorted wire near the heater which had been turned up to a too high temperature, leading to the release of magic smoke and banishment of the machine to the Pit of Despair, AKA the shadowy depths of one’s garage.

In this first installment, [Michael] cleaned up the machine and restored it to a working state. In the next part injection molding will be attempted again, which should give some idea of the feasibility of turning scraps of PLA and failed 3D prints into smooth injection molded parts, assuming you have the CNC machine or patience to carve out the requisite molds, of course.

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Arctos Robotics: Build A Robot Arm Out Of 3D Printer Spares?

ARCTOS is a 6-DOF robot arm based upon 3D printed mechanics running a modified version of GRBL firmware. Let’s get this straight now, the firmware is open source, but the hardware plans are a paid download, but for less than forty euros, we reckon the investment would be well worth it, judging from the quality of the build instructions and the software support already in place. Continue reading “Arctos Robotics: Build A Robot Arm Out Of 3D Printer Spares?”

DIY Self-Assembling 4D Printing

A 4D printed object is like a 3D printed object, but it changes shape or self-assembles when its environment changes. [Teaching Tech] has been reading about this technology and decided to try to replicate it using his conventional 3D printer.

His attempts to make a joint that changes when submerged in the water looked at several options: material that can absorb water, material that expands with temperature, and — the selected option — a dissolvable locking mechanism. Essentially, a hinge is held open by a water-soluble lock. When water dissolves the lock, the hinge can spring to its natural position.

Like most experiments, this one had a few false starts. But you always learn something each time. The final design had a TPU hinge and spring with PLA structural beams. The TPU required flat printing, so various pieces have to be rotatable so they can be placed in their final orientation after printing.

Usually, multi-material setups are for printing different colors of the same kind of plastic, it’s possible to use different plastics, but it can be tricky. As a compromise, [Teaching Tech] did one print using PLA and TPU, but printed the PVA locks in a separate pass and installed them on the print at the end. The first finished 4D print wasn’t entirely successful. The hot water slowly dissolved the PVA, but it also deformed the PLA. A redesign of the lock made a big difference.

We aren’t sure this is practical yet, but we are sure someone has a need for this technique and it could be made very practical with a little work. The last time we saw 4D printing, there were magnets involved. We think this is an exciting time where people aren’t just trying to get conventional printing to work well, but are pushing the envelope with new techniques like conical slicing, for example.

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