Stealing 3D Prints By Sound

In the open hardware world, we like to share 3D design files so that our friends and (global) neighbors can use and improve them. But we’ve all printed things from time to time that we’d like to keep secret. At least this is the premise behind this article in Science which proposes a novel method of 3D-printer-based industrial espionage: by recording the sound of the stepper motors and re-creating the toolpath.

Unfortunately, the article is behind a paywall so we’re short on the details, but everyone who’s played the Imperial March on their steppers has probably got the basic outline in their mind. Detecting the audio peak corresponding to a step pulse should be fairly easy. Disentangling the motions of two axes would be a bit harder, but presumably can be done based on different room-acoustic filtering of the two motors. Direction is the biggest question mark for us, but a stepper probably has a slightly audible glitch when reversing. Keeping track of these reversals could do the trick.

What do you think? Anyone know how they did it? Does someone with access to the full article want to write us up a summary in the comments?

[Thanks LVfire via Ars Technica]

[Edit: We were sent a copy of the full article (thanks [PersonUnknown]!) and it doesn’t explain any technical details at all. Save yourself the effort, and have fun speculating, because reading the article won’t help.]

Colorful Fan and LED Controller for 3D Printer

[Dave] just couldn’t take the ambient noise from his Lulzbot Mini anymore, so he built a fancy fan controller for it.

He measured some points on the printer’s Rambo controller board to see what actually got hot during a print. The hottest components were the motor drivers, so he taped a thermistor to them. He also placed one in the printer’s power supply. He replaced the main fan with a low noise model from Noctua (which have the most insanely fancy packaging you could imagine for a computer fan). The software on an Arduino Nano now idles the fan at an inaudible 650RPM, if an unacceptable temperature increase is detected, it increases the fan speed for a period, keeping everything nice and quietly cool.

The graphics display was added because, “why not?” A classic reason. The graphics runs on a hacked version of Adafruit’s library. It took him quite a while to get the graphics coded, but they add that extra bit of high-tech flair to keep the cool factor of the 3d printer up before they become as ubiquitous as toasters in the home. The code, fritzing board layout, 3D models, and a full build log is available at his site.

Meet Cartesio, Robot Artist

[Robottini] released plans for his robot, Cartesio, that is essentially an Arduino-controlled plotter made to create artwork. The good part about Cartesio is the low cost. [Robottini] claims it cost about $60 to produce.

The robot has an A3-size drawing bed and is practically the XY part of a 3D printer. In fact, most of the parts are 3D printed and the mechanical parts including M8 smooth rod. LM8UU bearings, and GT2 belts and pulleys. If you’ve built a 3D printer, those parts (or similar ones) should sound familiar.

The Arduino uses GRBL to drive the motors from GCODE. [Robottini] has three different workflows to produce drawings from applications like Inkscape. You can see some of the resulting images below.

We’ve covered GRBL before, and it is the heart of many motion control projects. If you’d rather draw on something less permanent, you might try this project.

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Error Correction of 3D Printers

From the very first RepRaps to the newest and latest printers off the Makerbot assembly line, nearly every consumer 3D printer has one significant shortcoming: it cannot recover from missed steps, slipped belts, or overheating stepper drivers. Although these are fairly rare problems, it does happen and is purely a product of the closed open-loop control system used in 3D printer firmware.

[Chris Barr] has come up with a rather clever solution to this problem. He’s designed a system that will detect and correct problems with the mechanics of 3D printers. It’s technically not a closed-loop control system, but it does allow him to get the absolute position of a nozzle on the build plate, detects error states, and can automatically calculate the number of motor steps per millimeter. It’s also much simpler than other closed loop control systems we’ve seen in the past, requiring only a few bits and bobs attached to the axes and to the printer controller board.

[Chris]’ system uses a magnetic encoding strip, a single chip, and a little bit of support circuitry. It’s actually not that much different from the moving axis on a desktop inkjet printer. It’s not closed loop, though; the firmware hack is only a ‘basic error correction’ that moves the nozzle back to where it should be. Although this is somewhat of a kludge, it is much simpler than refactoring the entire printer firmware.

In the video below, [Chris] demonstrates his solution for error correcting the printer by jerking his axis around during a print. The nozzle miraculously returns to where it should be, producing a usable part.

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Machines That Build Other Machines

When the RepRap project was founded in 2005, it promised something spectacular: a machine that could build copies of itself. RepRaps were supposed to be somewhere between a grey goo and a device that could lift billions of people out of poverty by giving them self-sufficiency and the tools to make their lives better.

While the RepRap project was hugely successful in creating an open source ecosystem around 3D printers, a decade of development hasn’t produced a machine that can truly build itself. Either way, it’s usually easier and cheaper to buy a 3D printer than to build your own.

[castvee8]’s entry into the 2016 Hackaday Prize does just what the RepRap project promised ten years ago. It’s all about building machines with the ability to reproduce, creating an ecosystem of machines to build household goods. The best part? You can 3D print most of the machines. It’s the RepRap project, but for mills, lathes, microscopes, and routers. It’s an entire shop produced entirely in a 3D printer.

The idea of creating a machine shop from the most basic building materials has been around for a while. At the turn of the last century, concrete lathes and mills bootstrapped industrial economies. Decades later, [David J. Gingery] created a series of books on building a machine shop starting with a charcoal foundry. The idea of building a shop using scrap and the most minimal tools is very old, but this idea hasn’t been updated to the era where anyone can buy a 3D printer for a few hundred dollars.

So far, [castvee8] has a few homemade machine tools on the workbench, including a lathe, a tiny mill easily capable of fabricating a few circuit boards, and a little drill press. They’re all machines that can be used to make other useful items, and all allow anyone to create the devices they need.

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The State Of 3D Printing At MRRF

Only a few days ago, a significant proportion of the Hackaday crew was leaving Goshen, Indiana after the fourth annual Midwest RepRap Festival. We go to a lot of events every year, and even when you include DEF CON, security conferences, ham swap meets, and Maker Faires, MRRF is still one of the best. The event itself is an odd mix of people rallying under a banner of open source hardware and dorks dorking around with 3D printer. It’s very casual, but you’re guaranteed to learn something from the hundreds of attendees.

Hundreds of people made the trek out to Goshen this year, and a lot of them brought a 3D printer. Most of these printers aren’t the kind you can buy at a Home Depot or from Amazon. These are customized machines that push the envelope of what consumer 3D printing technology. If you want to know what 3D printing will be like in two or three years, you only need to come to MRRF. It’s an incubator of great ideas, and a peek at what the future of 3D printing holds.

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3D Printing A Fake Product Leak

A few days ago you might have seen images floating around the net of the next Nintendo console controller, The Nintendo NX. There were so many pictures, it just had to be real!

Wrong. It was just [Frank Sandqvist] messing with everyone on the Internet. While phony product leaks are usually just photoshopped or 3D modeled renders, [Frank] took it a step further and actually designed a whole controller, 3D printed it, and took pictures of it. You might be wondering why he would do this. As a Reddit user points out there could be an excellent motive behind it:

You could also use it to get a job as a prop maker. It would look awesome on a CV that you made a prop that fooled the world — [Critters]

But, according to [Frank] it was really just for fun.

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