Getting It Right By Getting It Wrong: RepRap And The Evolution Of 3D Printing

March 2, 2016 by Elliot Williams 68 Comments

The beginning of the DIY 3D printing movement was a heady time. There was a vision of a post-scarcity world in which everything could and would be made at home, for free. Printers printing other printers would ensure the exponential growth that would put a 3D printer in every home. As it says on the front page: “RepRap is humanity’s first general-purpose self-replicating manufacturing machine.” Well, kinda.

RepRapOneDarwin-darwin — Original Darwin. Photo: Adrian Bowyer, founder of RepRap.

Just to set the record straight, I love the RepRap project. My hackerspace put our funds together to build one of the first few Darwins in the US: Zach “Hoeken” came down and delivered the cut-acrylic pieces in person. I have, sitting on my desk, a Prusa Mendel with 3D parts printed by Joseph Prusa himself, and I spent a fantastic weekend with him and Kliment Yanev (author of Pronterface) putting it together. Most everyone I’ve met in the RepRap community has been awesome, giving, and talented. The overarching goal of RepRap — getting 3D printers in as many peoples’ hands as possible — is worthy.

But one foundational RepRap idea(l) is wrong, and unfortunately it’s in the name: replication. The original plan was that RepRap printers would print other printers and soon everyone on Earth would have one. In reality, an infinitesimal percentage of RepRap owners print other printers, and the cost of a mass-produced, commercial RepRap spinoff is much less than it would cost me to print you one and source the parts. Because of economies of scale, replicating 3D printers one at a time is just wasteful. Five years ago, this was a controversial stance in the community.

On the other hand, the openness of the RepRap community has fostered great advances in the state of the DIY 3D printing art. Printers haven’t reproduced like wildfire, but ideas and designs have. It’s time to look back on the ideal of literal replication and realize that the replication of designs, building methods, and the software that drives the RepRap project is its great success. It’s the Open Hardware, smarty! A corollary of this shift in thought is to use whatever materials are at hand that make experimentation with new designs as easy as possible, including embracing cheap mass-produced machines as a first step. The number of RepRaps may never grow exponentially, but the quality and number of RepRap designs can.

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Hack A PS/2 Keyboard Onto Your Pi Zero

March 2, 2016 by Elliot Williams 31 Comments

Hacking for the Raspberry Pi Zero is a tricky proposition. Whatever you do, you’re working with a nominal five dollar board, so your hacks can’t be too highfalutin. For instance, a decent PS/2 to USB adapter will cost you as much as the Zero did, if not more. But if you just need to drive your Pi Zero from your old Model M (we hear you!) you’ve got to do it on the cheap.

So when prolific Pi hacker [mincepi] set out to build a PS/2 adapter, some corners were cut. PS/2 is a clocked data protocol, but the good news is that the clock doesn’t start and stop all the time as in I2C or SPI. This means that if you poll the data line at just the right frequency, at least in principle you’ll be able to ignore the clock.

So that’s what [mincepi] did. As you can see in the schematic and the banner image, there’s nothing to it. Two resistors provide the pullup voltage for the clock and data lines. And here’s a gem: a green LED with a drop voltage of about 2 V converts the 5 V data line down to something that the Pi Zero’s 3.3 V won’t get fried with. Cute, and very much in keeping with the spirit of the hack. You might be tempted to scrounge up a 3.3 V zener diode from somewhere just to be on the safe side, but remember, it’s a five dollar computer you’re protecting.

The last piece is a custom kernel module for the Pi that polls the PS/2 data line at just the right frequency. If you’re not a Linux person and “compiling a kernel module” sounds scary, [mincepi] has even put together a nice guide for the Raspbian distribution that he’s using. It should work with minor tweaks for any other distro.

We said [mincepi] is a prolific Pi hacker and here’s the proof: we’ve covered his quick-and-dirty VGA output hack and a scheme to get analog sound input into the Pi Zero just in the last couple of weeks. Hack on!

Moore’s Law Is Over (Again)

March 1, 2016 by Elliot Williams 52 Comments

According to this article in Nature, Moore’s Law is officially done. And bears poop in the woods.

Note when the time axis ends... — Note when the time axis ends…

There was a time, a few years back, when the constant exponential growth rate of the number of transistors packed into an IC was taken for granted: every two years, a doubling in density. After all, it was a “law” proposed by Gordon E. Moore, founder of Intel. Less a law than a production goal for a silicon manufacturer, it proved to be a very useful marketing gimmick.

Rumors of the death of Moore’s law usually stir up every couple years, and then Intel would figure out a way to pack things even more densely. But lately, even Intel has admitted that the pace of miniaturization has to slow down. And now we have confirmation in Nature: the cost of Intel continuing its rate of miniaturization is less than the benefit.

We’ve already gotten used to CPU speed increases slowing way down in the name of energy efficiency, so this isn’t totally new territory. Do we even care if the Moore’s-law rate slows down by 50%? How small do our ICs need to be?

Graph by [Wgsimon] via Wikipedia.

2,100 Mechanical Mechanisms

February 29, 2016 by Elliot Williams 29 Comments

[Nguyen Duc Thang]’s epic 2100 Animated Mechanical Mechanisms is one of the best YouTube channels we’ve ever seen. A retired mechanical engineer, [Nguyen Duc Thang] has taken on an immense challenge: building up 3D models of nearly every imaginable mechanism in Autodesk Inventor, and animating them for your amusement and enlightenment. And, no, we haven’t watched them all for you, but we’re confident that you’ll be able to waste at least a couple of hours without our help.

If you’re actually looking for something specific, with this many mechanisms demonstrated, YouTube is not the perfect lookup table. Thankfully, [Nguyen Duc Thang] has also produced a few hundred pages of documentation (PDFs, zipped) to go along with the series, with each mechanism classified, described, and linked to the video.

This is an amazing resource as it stands, and it’s probably a good thing that we don’t have access to the 3D files; between the filament cost and the time spent shepherding our 3D printer through 2,100 mechanisms, we’d be ruined. Good thing we don’t know about the Digital Mechanism and Gear Library or KMODDL.

Thanks [alnwlsn] for the tip!
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Password Extraction Via Front Doorbell

February 28, 2016 by Elliot Williams 52 Comments

Not a day goes by without another IoT security hack. If you’re wondering why you don’t want your front doorbell connected to the Internet, this hack should convince you.

The hack is unfathomably stupid. You press the button on the back of the unit that pairs the doorbell with your home WiFi network, and it transmits the password in the clear. Sigh. It’s since been fixed, and we suppose that’s a good thing, but we can’t resist thinking for a moment about an alternative implementation.

Imagine, like all previous non-IoT wireless doorbells, that the doorbell transmitted a not-very coded signal over an open frequency like 433 MHz to a receiver inside your home. Do the same with the video stream. Now the receiver can be connected to the Internet, and can be significantly more secure because it’s behind your locked front door. The attack surface presented to the outside world by the doorbell itself is small, and limited to faking a doorbell press or showing you pictures you don’t want to see. Yawn.

But because the outside doorbell unit could be connected to a network, it was. Now the attack surface extends into your home’s network, and if you’re like most people, the WiFi router was your only real defense.

Now we love the IoT, in principle. There are tons of interesting applications that need the sort of bandwidth or remote availability that the Internet provides. We’re just not convinced yet that a doorbell, or a fridge for that matter, meet the criteria. But it does add a hundred bucks to the price tag, so that’s good, right? What do you think? When does the risk of IoT justify the reward?

Thanks [Dielectric] for the tip!

Passive WiFi On Microwatts

February 26, 2016 by Elliot Williams 30 Comments

A lot of you use WiFi for your Internet of Things devices, but that pretty much rules out a battery-powered deployment because WiFi devices use a lot of juice. Until now. Researchers at the University of Washington have developed a passive WiFi implementation that uses only microwatts per device.

Working essentially like backscatter RFID tags do, each node has a WiFi antenna that can be switched to either reflect or absorb 2.4 GHz radiation. Your cell phone, or any other WiFi device, responds to this backscattered signal. All that’s missing is a nice steady signal to reflect.

A single, plugged-in unit provides this carrier wave for multiple WiFi sensor nodes. And here’s the very clever part of the research: to keep the carrier from overwhelming the tiny modulated signal that’s coming from the devices, the plugged-in unit transmits off the desired frequency and the battery-powered units modulate that at just the right difference frequency so that the resulting (mixed) frequency is in the desired WiFi band.

If you’re a radio freak, you’ll recognize the WiFi node’s action being just like a frequency mixer. That’s what the researchers (slightly mysteriously) refer to as the splitting of the analog transmission stage from the digital. The plugged-in unit transmits the carrier, and the low-power nodes do the mixing. It’s like a traditional radio transmitter, but distributed. Very cool.

There’s a bunch more details to making this system work with consumer WiFi, as you’d imagine. The powered stations are responsible for insuring that there’s no collision, for instance. All of these details are very nicely explained in this paper (PDF). If you’re interested in doing something similar, you absolutely need to give it a read. This idea will surely work at lower frequencies, and we’re trying to think of a reason to use this distributed transmitter idea for our own purposes.

And in case you think that all of this RFID stuff is “not a hack”, we’ll remind you that (near-field) RFID tags have been made with just an ATtiny or with discrete logic chips. The remotely-powered backscatter idea expands the universe of applications.

Thanks [Ivan] for the tip!

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Frackers: Inside The Mind Of The Junk Hacker

February 25, 2016 by Elliot Williams 116 Comments

Hackers can be a diverse bunch. My old hackerspace had folks ranging from NSA employees (ahem, independent security contractors) to space-probe pilots to anarchist vegan punks. And we all got along because we shared a common love for what we’re doing. One summer night we were out late in Adams Morgan and my vegan-punk friend reaches into the trash can and pulls out a discarded pepperoni Jumbo Slice.

“Wait a minute! Vegans don’t eat pepperoni pizza with cheese.” But my friend was a “freegan” — a vegan who, for ethical reasons, won’t buy meat or milk but who also won’t turn it down if it’s visibly going to waste. It’s actually quite a practical and principled moral proposal if you think about it: he’s not contributing to the use of animals that he opposes, but he gets to have a slice of pizza just the same. And fishing a slice of pizza, in a cardboard container, off the top of the trashcan isn’t as gross as you’d imagine, although it pays to be picky.

A Fracker is Born

That was the night that we realized we all had something deeper in common: we were all “frackers”. If you’ve been around hackers long enough, you’ll have noticed this tendency, but maybe you’ve never put a name to it. Tearing something apart, even if you might break it in the process, isn’t a problem if you fished it out of the e-waste stream to begin with. If you’re able to turn it into something, so much the better. It’s all upside. Need practice de-soldering tricky ICs? Looking for a cheap target to learn reverse engineering on? Off to the trashcan! No hack is too dirty, no method too barbaric. It’s already junk, and you’re a fracker.

Do you have a junk shelf where you keep old heatsinks in case you need to cut some up and use it? Have you used a heat gun more frequently for harvesting parts than for stripping paint? Do you know that certain satisfaction that you get from pulling some old tech out of the junk pile and either fixing it up again or, better yet, making it do something else? You might just be a fracker too.