injecto doing it's thing

Tiny Homemade Injection Molder

With 3D printing continually gaining ground, some hackers might not see the need for traditional injection molding. After all, you can tweak the code or the model and print dozens of different iterations with fairly minimal lead time. Things get trickier when you need to print hundreds or thousands of the same thing and that ten-hour print time adds up quickly. [Actionbox] built a tiny injection molder they dubbed INJEKTO to speed up their manufacturing.

The design was optimized to be accessible as it is held together with brackets and cheap aluminum flat stock. The hardest part to source is the heating chamber, as it is a piece of turned aluminum. A PID controller keeps the temperature relatively stable and heats the plastic pellets you can dump in the top. Next, you’ll need an external air compressor to power the dual 2″ pneumatic pistons. The pistons push the plastic out of the spring-loaded extruder nozzle. [Actionbox] is already planning on a second version with 4″ pistons that provide significantly more force to extrude larger amounts of plastic as the current version tops out at about 27 grams.

Injection molding still needs a heavy-duty mold to inject into, which can be hard to machine. So until we can 3D print an injection mold, this multi-head 3D printer is something in between a 3D printer and an injection molder, as it can print a dozen of the same thing, speeding up that print time.

Continue reading “Tiny Homemade Injection Molder”

From Table to Orbit: Salt

Saving Martian Colonists Using Table Salt And Rocket Science

Imagine for a moment that you are a member of an early Mars colony. You’re stranded, and the only way to get a message home is to launch a radio well above the surface. To make matters worse, you’ve got no rockets! It was this thought experiment that has motivated [Thoisoi2] to experiment with making a rocket motor using only ingredients and methods available to your average Martian colonist. The methods he has chosen can be seen in the video below the break.

If you skipped Rocketry 101, a quick refresher might help: Rockets work by burning a fuel in an enclosed chamber and then expelling it at high speed in one direction. To get the fuel to burn more quickly (and therefore adding more oomph to the angry end) a complement to the fuel called an Oxidizer is added. It serves to create an oxygen rich environment for the fuel to burn in. It’s the same reason a oxy-propane torch burns hotter than propane by itself.

Sugar Fuels Go Boom
The Sugar Powered Rocket Motor says “Boom!”

Firstly, a stranded Martian would need rocket fuel. If you recall the 1999 movie October Sky, four high school kids used table sugar as their fuel. You might also recall that those tended to get all explody. This volatility caused [Thoisoi2] to eschew sugar as a fuel in favor of a fuel that would also be available to any Martian colonist but be far less likely to cause Rapid Unplanned Disassembly.

What about the oxidizer? In October Sky, the boys experimented with Potassium Chlorate. This is commonly used in rockets but may be more difficult to obtain for your average Mars colonist. But, it turns out that Potassium Chlorate and Sodium Chlorate which can be prepared from table salt will work equally. It’s quite a bit more involved than that however.

Simply adding salt and fuel does not a rocket motor make. The nuances, the science, and the chemistry are all laid out in the wonderful video that [Thoisoi2] has put together, and we are sure you’ll enjoy it as much as we did.

You’ll also get to find out if our stranded Martian ever makes it home or if his potato farming was for naught.

We’d also like to echo the warning in the video: This is an experiment that is pretty dangerous, so don’t try this at home! Definitely try it at somebody else’s house first. Or on the surface of Mars.

Recently Hackaday covered another great attempt at making a rocket motor at home, although this one was a bit less successful, but every bit as interesting! Continue reading “Saving Martian Colonists Using Table Salt And Rocket Science”

Rainwater Storing Gojo Is A Stroke Of Genius

A traditional Ethiopian Gojo. Image courtesy of

The traditional Ethiopian Gojo is a circular domed dwelling constructed from a central vertical beam, and a surrounding structure of curved beams made from wood or bamboo. A covering of dried grass and mud completes the outer structure. These buildings are found everywhere in rural areas, due to their ease of construction, and availability of cheap materials. One major problem living in rural areas in developing countries is access to water. Ethiopian inventor [Anteneh Gashaw] knows a thing or two about the practicalities of living in a developing nation, and has come up with an ingenious take on the traditional Gojo. The idea is to replace the outer structure with pipes capable of storing rainwater. A collector plate on the top of the roof directs rain water into the pipes — with some small balancing tubes connecting them at the bottom — distributing the stored water evenly. A tap at the bottom of structure allows the pipes to be emptied on demand. Another interesting point about this design, is that the water adds some extra weight, for free, which gives the structure much improved stability in high winds, increasing safety.

{Anteneh] notes that proper water infrastructure is incredibly expensive, and just simply won’t happen. Well digging, installation of underground water tanks, and other such stop gap measures are great, but still need significant investment, and he believes that his modified Gojo idea will help reduce the problem of storing water during the rainy season, and reduce the pressure on centralised wells and other such community-orientated solutions. What’s more, it should be cheap. We shall watch with interest where this goes.

We’ve seen a few hacks from Africa nations, not many, just a few, but they are interesting ones. Like this DIY Helicopter that didn’t quite get to fly, and this e-waste 3D printer. We’ll keep our eye peeled for more!

Portable Pizza Oven Has Temperature Level Over 900

While it’s possible to make pizza from scratch at home right down to the dough itself, it’ll be a struggle to replicate the taste and exquisite mouthfeel without a pizza oven. Pizzas cook best at temperatures well over the 260°C/500°F limit on most household ovens while pizza ovens can typically get much hotter than that. Most of us won’t have the resources to put a commercial grade wood-fired brick oven in our homes, but the next best thing is this portable pizza oven from [Andrew W].

The build starts with some sheet metal to form the outer and inner covers for the oven. [Andrew] has found with some testing that a curved shape seems to produce the best results, so the sheet metal goes through rollers to get its shape before being welded together. With the oven’s rough shape completed, he fabricates two different burners. One sits at the back of the oven with its own diffuser to keep the oven as hot as possible and the other sits underneath a cordierite stone to heat from the bottom. Both are fed gas from custom copper plumbing and when it fires up it reaches temperatures hot enough that it can cook a pizza in just a few minutes. With some foldable legs the oven also ends up being fairly portable, and its small size means that it can heat up faster than a conventional oven too.

This is [Andrew]’s third prototype oven, and it seems like he has the recipe perfected. In fact, we featured one of his previous versions almost two years ago and are excited to see the progress he’s made in this build. The only downside to having something like this would be the potential health implications of always being able to make delicious pizzas, but that is a risk we’d be willing to take.

Continue reading “Portable Pizza Oven Has Temperature Level Over 900”

Three pendants that the article is describing, on a drafting mat.They're heart-shaped red PCBs with LEDs all around its perimeter, two CR2032-like batteries in its center.

Heart-Shaped Heartwarming Valentine’s Day Pendant

This is no ordinary heart-shaped PCB pendant project! To us, it’s also symbol representing the striking amount of love that [SaltyPaws] has put into its design and documentation. He tells us that he designed it for the two daughters he is raising, as an electronics and general STEAM introduction – with outstanding educational and aesthetic qualities, giving insights into a wide range of topics while looking . The PCB is mostly through-hole, making for easy soldering and quick return on the effort investment. The project is thought-out beyond the PCB, however – this pendant is designed to be wearable day-to-day, which is why it’s accompanied by a 3D-printed frame, protecting its wearer from sharp PCB edges and through-hole lead ends!

Open-sourcing things is a gift, and today, we are also the recipients. [SaltyPaws] has open-sourced everything involved – PCB files, 3D cover files, firmware, BOM, everything you would need to build your own version. All of this is in a GitHub repository, with detailed sourcing and assembly instructions in the – we couldn’t ask for more! If you have loved ones that would take delight in putting such a pretty pendant together, you have about a week to order the PCBs – after that, Chinese New Year will likely thwart your plans!

Looking for more accessories that double as electronics projects? We’ve covered a wide variety, even when it comes to pendants alone – check out this edge-lit fluorescent acrylic educational Maker Faire accessory, or this circuit sculpture BEAM-inspired bird-imitating one, or this tiny SAMD21-powered pendant with an IPS LCD!

Can Robots Give Good Hugs?

We could all use a hug once in a while. Most people would probably say the shared warmth is nice, and the squishiness of another living, breathing meatbag is pretty comforting. Hugs even have health benefits.

But maybe you’re new in town and don’t know anyone yet, or you’ve outlived all your friends and family. Or maybe you just don’t look like the kind of person who goes for hugs, and therefore you don’t get enough embraces. Nearly everyone needs and want hugs, whether they’re great, good, or just average.

So what makes a good hug, anyway? It’s a bit like a handshake. It should be warm and dry, with a firmness appropriate to the situation. Ideally, you’re both done at the same time and things don’t get awkward. Could a robot possibly check all of these boxes? That’s the idea behind HuggieBot, the haphazardly humanoid invention of Katherine J. Kuchenbecker and team at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany (translated). User feedback helped the team get their arms around the problem.

Continue reading “Can Robots Give Good Hugs?”

Bendy Straws

Compliant Mechanisms Hack Chat

Join us on Wednesday, January 26 at noon Pacific for the Compliant Mechanisms Hack Chat with Amy Qian!

When it comes to putting together complex mechanisms, we tend to think in a traditional design language that includes elements like bearings, bushings, axles, pulleys — anything that makes it possible for separate rigid bodies to move against each other. That works fine in a lot of cases — our cars wouldn’t get very far without such elements — but there are simpler ways to transmit force and motion, like compliant mechanisms.

Compliant mechanisms show up in countless products, from the living hinge on a cheap plastic box to the nanoscale linkages etched into silicon inside a MEMS accelerometer. They reduce complexity by putting the elasticity of materials to work and by reducing the number of parts it takes to create an assembly. And they can help make your projects easier and cheaper to build — if you know the secrets of their design.

join-hack-chatAmy Qian, from the Amy Makes Stuff channel on YouTube,  is a mechanical engineer with an interest in compliant mechanisms, so much so that she ran a workshop about them at the 2019 Superconference. She’ll stop by the Hack Chat to share some of what she’s learned about compliant mechanisms, and to help us all build a little flexibility into our designs.

Our Hack Chats are live community events in the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, January 26 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.


Continue reading “Compliant Mechanisms Hack Chat”