Month: January 2021

Programmable Filament For Multicolor Printing

January 15, 2021 by 29 Comments

A recent research paper shows a way to create multicolor 3D prints using a single extruder if you are too lazy to babysit the machine and switch filament. The concept: print your own “programmable” filament that has the right colors in the right place. This is the same idea as manually splicing filament but presumably is more efficient since the process works with one color at a time and doesn’t repeat. In other words, to print the 64 squares of a chessboard you’d swap filament at least 64 times on each layer. Using programmable filament, you’d load one spool, print half of the filament, load another spool, print the other half, and then finally load the newly created filament and print the chessboard. Notice that the first two operations aren’t printing the chessboard. They are printing the spool of filament you feed through on the third pass.

There are machines made to do this, of course, although they generally just splice lengths of filament together for you automatically. Using one filament solves the problems of keeping multiple heads in alignment as well as the added cost and complexity. However, you now have different problems such as the transition between materials and knowing exactly how much material will be at each point in the print.

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A 136 Euro Pulse Jet For Some No-Firework Lockdown Fun

January 15, 2021 by 21 Comments

With the aim of reducing virus transmission due to gatherings during the pandemic, the Dutch government have banned fireworks. The people of the Netherlands like their noisy things so we’re told that the ban has been widely flouted, but [Build Comics] are a law-abiding group of workshop tool heroes. For their lockdown noise, they created an entirely-legal pulsejet. The interesting part is that it was made entirely using fairly basic tools on a minimalist budget, with TIG and MIG eschewed in favour of a mundane stick welder.

The form of the pulse jet will probably be familiar as it has been taken from other published designs. A long tube is bent back upon itself with a combustion chamber placed in one of its arms such that the jet forms a resonant chamber that produces continuous pulses of exhaust gas. This one is made from stainless steel tube, and the exhaustive documentation should be worth a look for anyone tempted to make their own. Welding thin sheet with a stick welder requires quite a bit of skill, and in a few places they manage to burn a hole or two. One requires a patch, but the time-honoured technique of running a bead around the edge manages to successfully close another.

Their first attempt to fire it up using a leaf blower with a 3D-printed adapter fails, but following the construction of a more resilient part and a more efficient gas injector the engine starts. It’s then taken out on a farm for some serious noise without too many angry neighbours, as you can see in the video below the break.

The hero tools of Build Comics have appeared here before, most recently with an analogue meter clock.

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Dynamic Map Of Italy On A PCB

January 14, 2021 by 9 Comments

While most PCBs stick to tried-and-true methods of passing electrons through their layers of carefully-etched copper, modern construction methods allow for a large degree of customization of most aspects of these boards. From solder mask to number of layers, and even the shape of the board itself, everything is open for artistic license and experimentation now. [Luca] shows off some of these features with his PCB which acts as a live map of Italy.

The PCB is cut out in the shape of the famous boot, with an LED strategically placed in each of 20 regions in the country. This turns the PCB into a map with the RGB LEDs having the ability to be programmed to show any data that one might want. It’s powered by a Wemos D1 Mini (based on an ESP8266) which makes programming it straightforward. [Luca] has some sample programs which fetch live data from various sources, with it currently gathering daily COVID infection rates reported for each of the 20 regions.

The ability to turn a seemingly boring way to easily attach electronic parts together into a work of art without needing too much specialized equipment is a fantastic development in PCBs. We’ve seen them turned into full-color art installations with all the mask colors available, too, so the possibilities for interesting-looking (as well as interesting-behaving) circuits are really opening up.

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Beam Dump Makes Sure Your Laser Path Is Safely Terminated

January 14, 2021 by 37 Comments

Between hot things, sharp things, and spinny things, there’s more than enough danger in the average hacker’s shop to maim and mutilate anyone who fails to respect their power. But somehow lasers don’t seem to earn the same healthy fear, which is strange considering permanent blindness can await those who make a mistake lasting mere fractions of a second.

To avoid that painful fate, high-power laser fan [Brainiac75] undertook building a beam dump, which is a safe place to aim a laser beam in an experimental setup. His version has but a few simple parts: a section of extruded aluminum tubing, a couple of plastic end caps, and a conical metal plumb bob. The plumb bob gets mounted to one of the end caps so that its tip points directly at a hole drilled in the center of the other end cap. The inside and the outside of the tube and the plumb bob are painted with high-temperature matte black paint before everything is buttoned up.

In use, laser light entering the hole in the beam dump is reflected off the surface of the plumb bob and absorbed by the aluminum walls. [Brainiac75] tested this with lasers of various powers and wavelengths, and the beam dump did a great job of safely catching the beam. His experiments are now much cleaner with all that scattered laser light contained, and the work area is much safer. Goggles still required, of course.

Hats off to [Brainiac75] for an instructive video and a build that’s cheap and easy enough that nobody using lasers has any excuse for not having a beam dump. Such a thing would be a great addition to the safety tips in [Joshua Vasquez]’s guide to designing a safe laser cutter.

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ESP32 Soil Monitors Tap Into Ultra-Low Power Mode

January 14, 2021 by 26 Comments

Soil moisture sensors are cheap and easy to interface with, to the point that combining one with an Arduino and blinking an LED when your potted plant is feeling a bit parched is a common beginners project. But what about on the long term? Outside of a simple proof of concept, what would it take to actually read the data from these sensors over the course of weeks or months?

That’s precisely the question [derflob] recently had to answer. The goal was to build a device that could poll multiple soil sensors and push the data wirelessly into Home Assistant. But since it would be outside on the balcony, it needed to run exclusively on battery power. Luckily his chosen platform, the ESP32, has some phenomenal power saving features. You just need to know how to use them. Continue reading “ESP32 Soil Monitors Tap Into Ultra-Low Power Mode” →

OpenCV Spreads Smart Camera Joy To See Ideas Come To Life

January 14, 2021 by 4 Comments

Do you have a great application for computer vision, but couldn’t spare the cost of hardware needed to build it? Or perhaps you just need a deadline to pull you away from endless doom scrolling? Either way, the OpenCV team wants you to enter their OpenCV AI Competition 2021 and they’re willing to pitch in hardware to make it happen.

This competition is part of OpenCV’s 20th anniversary celebration, and the field of machine vision has changed a lot in those two decades. OpenCV started within Intel harnessing power of their high end CPUs, but today the excitement is around specialized acceleration hardware for vision processing. Which is why OpenCV put their support and lent their name to the OpenCV AI Kit (OAK) Kickstarter we covered a few months ago. Since then, the hardware was produced and starting to arrive in project backer’s hands. (Barring pandemic-related shipping restrictions…)

This shiny new hardware is the competition’s focus. Phase one solicits team proposals for putting an OAK-D’s power to novel use. University teams may have up to ten members, general teams are limited to four. Each team’s geographic home will put them in one of six global regions. Proposals must be submitted by January 27th, 2021. By February 11th, judges will select the best twenty-five general and ten university team proposals from each region, and every member of the team gets an OAK-D unit to turn their idea into reality by phase two deadline of June 27th. That’s up to 1,200 OAK-D modules available to anyone who can convince the judges they have a great idea and they are capable of bringing it to fruition. Is that you? Of course it is!

Teams will also receive additional resources such as an allotment of cloud compute credits to train their models, and naturally all tutorials and sample code released as part of OAK Kickstarter. No explicit resource for project team organization is mentioned, but of course our own Hackaday.io is available to support you. Best of luck to everyone who enters and we look forward to seeing all the projects this contest will bring to life.

Basics Of Remote Cellular Access: Connecting Via VPN

January 14, 2021 by 9 Comments

You’ve got a machine hooked up to the Internet via a shiny new cellular modem, which you plan to administer remotely. You do a quick check on the external IP, and try and log in from another PC. Try as you might, SSH simply won’t connect. What gives?

The reality of the modern internet is that most clients no longer get their own unique IPv4 address. There simply aren’t enough to go around anymore. Instead, most telecommunications operators use Carrier Grade Network Address Translation which allows a single external address to be shared by many customers. This can get in the way of direct connection attempts from the outside world. Even if that’s not the case, most cellular operators tend to block inbound connections by default. However, there is a way around this quandary – using a VPN. Continue reading “Basics Of Remote Cellular Access: Connecting Via VPN” →