Reducing Drill Bit Wear The Cryogenic Way

September 7, 2019 by 13 Comments

There are a lot of ways that metals can be formed into various shapes. Forging, casting, and cutting are some methods of getting the metal in the correct shape. An oft-overlooked aspect of smithing (at least by non-smiths) is the effect of temperature on the final characteristics of the metal, such as strength, brittleness, and even color. A smith may dunk a freshly forged sword into a bucket of oil or water to make the metal harder, or a craftsman with a drill bit might treat it with an extremely cold temperature to keep it from wearing out as quickly.

Welcome to the world of cryogenic treatment. Unlike quenching, where a hot metal is quickly cooled to create a hard crystal structure in the metal, cryogenic treatment is done by cooling the metal off slowly, and then raising it back up to room temperature slowly as well. The two processes are related in that they both achieve a certain amount of crystal structure formation, but the extreme cold helps create even more of the structure than simply tempering and quenching it does. The crystal structure wears out much less quickly than untreated steel, therefore the bits last much longer.

[Applied Science] goes deep into the theory behind these temperature treatments on the steel, and the results speak for themselves. With the liquid nitrogen treatments the bits were easily able to drill double the number of holes on average. The experiment was single-blind too, so the subjectivity of the experimenter was limited. There’s plenty to learn about heat-treated metals as well, even if you don’t have a liquid nitrogen generator at home.

Thanks to [baldpower] for the tip!

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Is Solar Right For You? Find Out!

September 7, 2019 by 22 Comments

Solar panels are revolutionizing the electric power industry, but not everyone is a good candidate for rooftop solar. Obviously people in extreme northern or sothern latitudes aren’t going to be making a ton of energy during the winter compared to people living closer to the equator, for example, but there are other factors at play that are more specific to each individual house. To find out if any one in particular will benefit from solar panels, [Jake] and [Ryan]’s solar intensity sensor will help you find out.

The long-term intensity tracker is equipped with a small solar panel and a data recording device, properly contained in a waterproof enclosure, and is intended to be placed in the exact location that a potential solar installation will be. Once it has finished gathering data, it will help determine if it makes economical sense to install panels given that the roof slope might not be ideal, landscaping may be in the way, or you live in a climate where it rains a lot in the summer during peak production times.

As we move into the future of cheap, reliable solar panels, projects like this will become more and more valuable. If you’re not convinced yet that photovoltaics are the way of the future, though, there are other ways of harnessing that free solar power.

Putting 3D Printed Speaker Drivers To The Test

September 7, 2019 by 15 Comments

Over the years, we’ve seen numerous projects that attempted to 3D print speaker enclosures that deliver not only a bit of custom flair, but hopefully halfway decent sound. Though as you’d probably expect, the drivers themselves are always standard run-of-the mill hardware mounted into the plastic enclosure. But given the research being conducted by [Paul Ellis], that might not be a safe assumption for much longer.

His quest to develop a full-range 3D speaker has taken him through several design revisions over the last two years, with each one being put through testing procedure that compared its frequency response to “real” speakers from manufacturers like Dayton and Bose. The project is very much ongoing, but a recently completed iteration of the driver design managed to exceed 80 dB at 1 W. In terms of audio quality, [Paul] reports they can hold their own against commercially available drivers. You can hear for yourself in the video after the break.

Ultimately, he hopes to be able to sell his 3D printed speakers in kit form to anyone who’s looking for the last word in bespoke audio hardware. The idea being that the drivers and enclosure will be completely modular, allowing the user to swap out individual components for ones printed (or not) in different materials so they can tune the in-person sound to their exact specifications. To facilitate this rapid reconfiguring of the drivers, the designs use some neat tricks like having the magnets be removable rather than glued in so they could be swapped out non-destructively.

This isn’t the first fully 3D printed speaker driver we’ve ever seen, Formlabs showed one off that was made on their SLA printer back in 2015, and we actually saw a rudimentary take on the same idea earlier this year. But the work that [Paul] has done here is certainly the most thorough, and dare we say practical, take we’ve ever seen on the concept.

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Complex Impedances Without The Pain

September 7, 2019 by 13 Comments

Any grizzled electronic engineer will tell you that RF work is hard. Maintaining impedance matching may be a case of cutting wires to length at lower frequencies, but into the low centimetre and millimetre wavelengths it becomes a Dark Art aided by mysterious and hugely expensive test equipment beyond the reach of mere mortals. A vector network analyser or VNA may be beyond the reach of many, but [Tomasz Wątorowski] is here to tell us about how with some resistors, mathematics, and a bit of lateral thinking its functions may be replicated with a more modestly equipped bench.

It’s not a method for the faint-hearted as the mathematics are of the variety that you probably learned as an undergraduate but let slip from your memory with thanks after the course ended. The method involves measuring the return loss both with and without a resistor of known value in series with the antenna, these figures allow the real and imaginary components of the antenna’s impedance to be calculated. There is a further piece of work though, this method doesn’t determine whether the antenna is capacitive or inductive. Repeating the measurement with either a capacitive or inductive matching network allows this to be determined, and the value of the appropriate matching component to be calculated.

If you are interested in this kind of work, start with a primer on RF design.

Complex impedance matching using scalar measurements, math and resistors

Homebrew Oscillator Is In A Glass By Itself

September 7, 2019 by 8 Comments

Great things happen when we challenge ourselves. But when someone else says ‘I bet you can’t’ and you manage to pull it off, the reward is even greater. After [WilkoL] successfully made a tuning fork oscillator, his brother challenged him to make one out of a wine glass. We’ll drink to that!

First, [WilkoL] needed to find a way to make the wine glass vibrate continuously without having to stand there running a moistened finger around the edge. A piezo speaker mounted close by did the trick. Then he had to detect the sound waves, amplify them, and feed them back in.

After toying with the idea of making a laser microphone, and tossing aside the idea of a regular microphone (because squealing feedback), he settled on using light. LEDs didn’t work, probably because the light is too divergent. But he found out that by aiming a laser just right, the curve of the wine glass modulates the light, and the waves can be detected with a phototransistor.  Then it was just a matter of amplifying the the sound and feeding it back to the piezo.

In the demo video after the break, you can see the vibrations in the glass manifest once he pours in some water. As anyone who’s ever played the water glasses can tell you, this also changes the frequency. [Editor’s note: I expected a much larger change in pitch. Not sure what’s going on here.]

Speaking of, here’s a steampunky glass armonica that uses an old turntable motor to rotate the wine glass, and a pneumatic cylinder to raise and lower the water level.

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Portable PS2 With A Side Of Pi

September 6, 2019 by 5 Comments

Home games consoles have occupied a special space in the marketplace over the last 3 decades. The crowning jewels of their respective companies, they inspired legions of diehard fans and bitter enmities against followers of alternative hardware. For some, a mere handheld is a watered down experience that simply won’t do. Nay, the console itself must become portable!

It’s this line of thinking that may have inspired [Darkwing Mod] to produce this elegant portable PlayStation 2. Started at the end of 2013, it’s the product of six years of on-and-off work, a situation familiar to many a hacker. It packs an original PS2 motherboard inside a slick black-and-blue case, expertly crafted with plastic and putty for a smooth finish. A Raspberry Pi 2 also lives inside, serving up games over a Samba share. This method was chosen for its short load times and robustness for the portable form factor, versus trying to squeeze a full DVD drive inside. It’s used in combination with Free MCBoot to load the games.

The worklog is extensive, detailing the long road to completion. It’s clear that this was a labor of love, and we hope it sees many hours of use now that it’s up and running. It’s not the first portable PS2 we’ve seen, and it likely won’t be the last. Video after the break.

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Linux Fu: Interactive SSH Applications

September 6, 2019 by 4 Comments

[Drew DeVault] recently wrote up some interesting instructions on how to package up interactive text-based Linux commands for users to access via ssh. At first, this seems simple, but there are quite a few nuances to it and [Drew] does a good job of covering them.

One easy way — but not very versatile — is to create a user and make the program you want to run the default shell. The example used is to make /usr/bin/nethack the shell and now people can log in as that user and play nethack. Simple, right? However, there are better ways to get there.

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