Banksy’s Barely Believable Batteries

Nearly a decade ago my friend [Dru] gave me an unforgettable tour late at night of Stokes Croft, the inner suburb of Bristol known at the time for its counterculture and artistic scene. It’s a place dominated by building-sized graffiti and murals, and it has a particular association with the Bristolian street artist [Banksy]. If you’ve not seen a Banksy in the wild, the place to do it is by Bristol Saturday night street lighting to the sound of passing revelers and traffic on the A38.

[Banksy] is famous aside from his anonymity, for his pranks upon the art world. The (real) elephant in the room or the Dismalland theme park are his stock in trade, and you may have seen another prank of his in the news in the last day. One of his paintings, the 2006 Girl With A Balloon sold at auction for over a million quid, and as the gavel fell a hidden shredder in the picture frame sprang into life and partially shredded the canvas. The report suggests that a number of [Banksy]’s associates were present at the event, and that one of them was detained with a device that might have been a remote control trigger for the shredder. The quote from Sotheby’s Europe head of Contemporary Art, [Alex Branczik] says it all: “We got Banksy’d”.

The interior of the Banksy shredder frame, taken from a frame of the video.
The interior of the Banksy shredder frame, taken from a frame of the video.

[Banksy]’s cool and all that, but where’s the hack? The artist briefly put up a video with a few details, but aside from showing us a row of craft knife blades and a tantalizing but fleeting glimpse of a few equipment enclosures, it’s short on technical details. We can see what appears to be at least one motor, and those white boxes may be batteries, but that’s it.

This hasn’t stopped some fevered speculation as to how the feat was achieved. A home-made shredder would require a significant amount of readily available power, and since this one has seemingly lain undetected within the frame since 2006, that power source needs to have possessed both exceptional  energy density and retention. We can’t imagine many consumer grade batteries in 2018 being able to retain a charge for twelve years, so how on earth did he do it? Our best guess is that a primary battery was involved, as anyone who has found a neglected Duracell in a box of electronics from their youth will tell you it’s not unknown for decent quality alkaline cells to live well beyond their shelf lives, and other chemistries are specifically designed with that property in mind. Even so, for the cells to power a receiver circuit in standby for so long would certainly tax their capabilities, so it has also been suggested that a concealed switch could have been flipped by a [Banksy] accomplice during the viewing phase to activate the system. There are still so many unanswered questions that it’s certainly piqued our technical curiosity. Sadly we don’t know [Banksy] to ask him how he did it, but we welcome speculation both informed and otherwise in the comments.

Our own [Joe Kim]'s tribute to the work in question.
Our own [Joe Kim]’s tribute to the work in question.
Meanwhile the piece itself lies half shredded and protruding from the base of the frame. On the face of it that’s ruined the painting as an artwork, but of course this is a Banksy. Normal rules seem not to apply, so the notoriety it has received will no doubt mean that its shredded remains are an artwork in themselves, and possibly even one worth more.

Banksy owners worldwide are no doubt now paying a huge amount more attention to the artist’s frames than previously, but Hackaday readers need not worry. Our London Unconference logo and stickers featured a [Joe Kim] homage to the Banksy in question, which we can guarantee does not incorporate an artist’s shredder.

 

Scratch-Fabricated Plastic Gobbling Shredder Brings Recycling Home

[Jason Knight], an intern at FabLab RUC, has worked hard for 9 months to make a sheet plastics shredder for HDPE and LDPE from things like plastic bags, bubble wrap and air cushion packaging with the goal of recycling the shredded plastic. Why shred these things? When broken down to smaller pieces they can be melted in a consumer grade oven (like where you cook your frozen pizzas) then molded into new objects or extruded into 3D printing filament.

We especially like his big homemade 1.1 inch (30mm) thick wooden gears, for transferring the rotation from the motor to the cutting shafts while giving a step up in torque. As you can see in the video below, the gears definitely add an extra look of power to the machine.

The blades are the shape you most often see in shredders, gear-like disks side-by-side with teeth cut from them that pull the plastic in while shredding it (in contrast to this lower-throughput experimental DIY shredder made with two steel pipes). [Jason’s] multiple teeth are a bit of work to fabricate — not only were all the teeth milled from sheet metal but they then had to be individually sanded to remove burrs from the edges. It was worth it, as this has no problem chewing waste plastics to pieces.

Shredders can be dangerous machines for wandering fingers so [Jason] added a few safety features. Those include a drawer that you open to insert your plastic into the shredding area and a guard that completely surrounds the gears. And both features include transparent plastic areas so that you can still watch the impressive working parts in action.

Continue reading “Scratch-Fabricated Plastic Gobbling Shredder Brings Recycling Home”

Think Globally, Build Locally With These Open-Source Recycling Machines

Walk on almost any beach or look on the side of most roads and you’ll see the bottles, bags, and cast-off scraps of a polymeric alphabet soup – HDPE, PET, ABS, PP, PS. Municipal recycling programs might help, but what would really solve the problem would be decentralized recycling, and these open-source plastics recycling machines might just jump-start that effort.

We looked at [Precious Plastic] two years back, and their open-source plans for small-scale plastic recycling machines have come a long way since then. They currently include a shredder, a compression molder, an injection molder, and a filament extruder. The plans specify some parts that need to be custom fabricated, like the shredder’s laser-cut stainless steel teeth, but most can be harvested from a scrapyard. As you can see from the videos after the break, metal and electrical fabrication skills are assumed, but the builds are well within the reach of most hackers. Plans for more machines are in the works, and there’s plenty of room to expand and improve upon the designs.

We think [Precious Plastic] is onto something here. Maybe a lot of small recyclers is a better approach than huge municipal efforts, which don’t seem to be doing much to help.  Decentralized recycling can create markets that large-scale manufacturing can’t be bothered to tap, especially in the developing world. After all, we’ve already seen a plastic recycling factory built from recycled parts making cool stuff in Brazil.

Continue reading “Think Globally, Build Locally With These Open-Source Recycling Machines”

A Different Kind Of Plastic Shredder For 3D Filament Making

Haven’t you heard? You can make your own 3D filament nowadays from plastic granules (10X cheaper than filament), or even by recycling old plastic! Except if you’re recycling plastic you will have to shred it first…

[David Watkins] came up with a different way of shredding plastic. Typically we’ve seen shrunken versions of giant metal shredders used to dice up plastic into granules that can be melted down and then extruded back into filament. These work with a series of sharp toothed gears that kind of look like a stack of circular saw blades put together inside of a housing.

But that can be rather pricey. [David’s] method is super cheap, and you can do it at home with minimal tools, and maybe $10 or less worth of parts?

Continue reading “A Different Kind Of Plastic Shredder For 3D Filament Making”