Hinges Live Inside 3D Prints

May 1, 2023 by Bryan Cockfield 5 Comments

Since desktop 3D printers have become more common, we’ve seen dramatic shifts in all kinds of areas such as rapid prototyping, antique restoration, mass production of consumer goods, or even household repairs that might not have been possible otherwise. There are a lot of unique manufacturing methods that can be explored in depth with a 3D printer as well, and [Slant 3D] demonstrates how one such method known as the living hinge can be created with this revolutionary new tool.

Living hinges, unlike a metal hinge you might pick up at a hardware store, are integrated into the design of the part and made of the same material. Typically found in plastic containers, they allow for flexibility while keeping parts count and cost low. The major downside is that they create stresses in the materials when used, so their lifespan is finite. But there are a number of ways to extend their life, albeit with a few trade-offs.

The first note is to make sure that you’re using the right kind of plastic, but after that’s taken care of [Slant 3D] builds a few flexible parts starting with longer circular-shaped living hinge which allows greater range of motion and distributes the forces across a wider area, at a cost of greater used space and increased complexity. A few other types of living hinges are shown to use less space in some areas, but make the hinges only suitable for use in other narrower applications.

One of the more interesting living hinges he demonstrates is one that’s more commonly seen in woodworking, known there as a kerf bend. By removing strips of material from a sheet, the entire sheet can be rotated around the cuts. In woodworking this is often done by subtracting material with a CNC machine or a laser cutter, but in 3D printing the voids can simply be designed into the part.

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Beehive In A Bottle

January 21, 2023 by Bryan Cockfield 49 Comments

One of the most common types of beekeeping hive is based around the Langstroth hive, first patented in the United States in 1852. While it does have some nice features like movable frames, the march of history has progressed considerably while this core of beekeeping practices has changed very little. But that really just means that beekeeping as a hobby is rife with opportunities for innovation, and [Advoko] is pioneering his own modern style of beehive.

In nature, bees like to live inside of things like hollowed-out tree trunks, so he has modeled his hive design after that by basing it around large inverted plastic bottles. Bees can enter in the opening at the bottle and build their comb inside from the top down. The bottles can be closed and moved easily without contacting the bees, and he even creates honey supers out of smaller bottles which allows honey to be harvested without disturbing the core beehive.There are a number of strategies to improve the bees’ stay in the bottles as well, such as giving them wooden skewers in the bottle to build their comb on and closing the bottles in insulation to help the hives regulate their temperature more evenly and to keep them dark.

He hopes this idea will help inspire those with an interest in the hobby who wouldn’t otherwise have the large amount of money it takes to set up even a few Langstroth-type hives. Even if you don’t live in a part of the world where the Langstroth hive is common, this system still should be possible to get up and running with a minimum of financial investment. Once you’ve started, though, take a look at some other builds which augment the hive with some monitoring technology.

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The Physics Behind The Collapse Of A Huge Aquarium

December 20, 2022 by Jenny List 144 Comments

At the end of last week Aquadom, the world’s largest cylindrical aquarium, unexpectedly shattered and caused an emergency as it flooded both the Berlin hotel that housed it and the surrounding streets. From an engineering perspective it’s a fascinating story, because its construction was such that this shouldn’t have happened. We have an analysis of what might have gone wrong from [Luis Batalha] (Nitter), and from it we can learn a little about the properties of the plastic used.

The aquarium was made of an acrylic polymer which has an interesting property — at a certain temperature it transitions between a glass-like state and a rubber-like one. Even at room temperature the acrylic is well below the transition temperature, but as the temperature drops the acrylic becomes exponentially more brittle. When the outside temperature dropped to well below zero the temperature also dropped in the foyer, and the high water pressure became enough to shatter the acrylic.

Sadly few of the fish from the aquarium survived, but fortunately nobody was killed in the incident. News coverage shows how the force of the water destroyed the doors and brought wreckage into the street, and we’re guessing that it will be a while before any other hotel considers such a project as an attraction. Meanwhile we’ve gained a little bit of knowledge about the properties of acrylic, which might come in handy some day.

Header: Chrissie Sternschuppe, CC BY-SA 2.0.

Conducting Plastic Can Replace Metal

November 6, 2022 by Al Williams 45 Comments

The University of Chicago has announced they have created a material that behaves like plastic but conducts like metal. They also say they don’t fully understand why it works yet. Usually, good conductors like metals have very orderly atomic structures, something that plastics tend not to have.

The material is based on nickel, carbon, and sulfur. The resulting material was conductive and stable. However, the atomic structure isn’t orderly like a traditional conductor.

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Printed Axial Generator Is Turned By Hand

October 15, 2022 by Bryan Cockfield 19 Comments

While desktop 3D printing is an incredible technology, it’s got some pretty clear limitations. Plastic parts can be produced quickly in a 3D printer but can be more expensive or take longer to make than parts from materials like wood. Plastic parts can also be weaker than materials like metal. If a 3D printer is all you have on hand, though, you can often make some design choices that improve the performance of a plastic part over other materials. That’s what [1970sWizard] did to make this axial hand-cranked generator.

Besides a few pieces of off-the-shelf hardware and the wire and magnets, the entire generator is printed. The actual generator is made from coils of wire with exposed leads which snap into a plastic disc which acts as the generator’s stator. The magnets also snap into a separate disc which is the rotor of the generator and is attached to the drivetrain, with no glue or fasteners required. A series of gears on two other axes convert the torque from the hand crank into the high speed necessary to get usable electricity out of the generator.

The separate gear shafts were necessary to keep from needing a drillpress, which would have allowed fewer axes to be used. This entire machine can be built almost entirely with a desktop 3D printer, though, which was one of the design goals. While it’s largely a proof-of-concept, the machine does generate about 100 mW of power which is enough to slowly charge USB devices, power lights, or provide other sources of very small amounts of energy. If you do have access to some metalworking tools, though, take a look at this hand-cranked emergency generator.

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Casting Metal With A Microwave And Vacuum Cleaner

September 29, 2022 by Bryan Cockfield 39 Comments

Metalworking might conjure images of large furnaces powered by coal, wood, or electricity, with molten metal sloshing around and visible in its crucible. But metalworking from home doesn’t need to use anything more fancy than a microwave, at least according to [Denny] a.k.a. [Shake the Future]. He has a number of metalworking tools designed to melt metal using a microwave, and in this video he uses them to make a usable aluminum pencil with a graphite core.

Before getting to the microwave kiln, the pencil mold needs to be prepared. A 3D-printed pencil is first created with the graphite core, and then [Denny] uses a plaster of Paris mixture to create the mold for the pencil. The 3D printed plastic is left inside the mold and placed in the first microwave kiln, which is turned on just enough to melt the plastic out of the mold, leaving behind the graphite core. From there a second kiln goes into the microwave to melt the aluminum.

Once the molten aluminum is ready, it is removed from the kiln and poured in the still-warm pencil mold. This is where [Denny] has another trick up his sleeve. He’s using a household vacuum cleaner to suck the metal into place before it cools, creating a rudimentary but effective vacuum forming machine. The result is a working pencil, at least after he wears down a few razor blades attempting to sharpen the metal pencil. For more information about how [Denny] makes these microwave kilns, take a look at some of his earlier projects.

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PET Bottles Diligently Turned Into Filament

August 25, 2022 by Bryan Cockfield 21 Comments

While the price of 3D printers has come down quite a lot in the past few years, filament continues to be rather pricey especially for those doing a lot of printing. This has led to some people looking to alternatives for standard filament, including recycling various forms of plastic. We’ve seen plenty of builds using various materials, but none so far have had this level of quality control in the final project.

What sets this machine apart from others is that it’s built around an Arduino Nano and includes controls that allow the user to fine-tune a PID controller during the conversion of the recycled plastic into filament. Different plastic bottles have different material qualities, so once the machine is started it can be adjusted to ensure that the filament produced has the exact specifications for the printer. The PCB is available for download, and the only thing that needs to be done by hand besides feeding the machine to start it is to cut the plastic into strips for the starter spool. There is also a separate 3D printed tool available to make this task easy, though.

Not only could this project save printing costs, but it also keeps harmful plastics out of landfills and other environments. Recycling plastic tends to be quite difficult since producing new plastic is incredibly cheap, and the recycled material can’t be used as often as other materials such as aluminum. But there are still plenty of people out there trying to reuse as much of it as they can.

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