3D Internal Structure For Better 3D Printed Objects

June 10, 2016 by Brian Benchoff 54 Comments

Makerbot is in the gutter, 3D Systems and Stratasys stock is only a shadow of their 2014 glory, but this is the best year 3D printing has ever had. Machines are now good and cheap, there’s a variety of various thermoplastic filaments, and printing useful objects – instead of just plastic trinkets – is becoming commonplace.

Gradient-Grid — The standard rectilinear infill from Slic3r

There’s one area of 3D printing that hasn’t seen as much progress, and it’s the software stack. Slicing, the process of turning a 3D object into a Gcode file for a printer has been basically the same for the last few years. Dual extrusion is still a mess, and automated bed leveling is still in its infancy.

One aspect of slicing that has been severely overlooked is infill. Obviously, you don’t want to print plastic trinkets completely solid – only the outside surface matters, and a part with 100% infill is just a waste of plastic. Different slicers have come up with different ways of filling the inside of a print, usually with a grid of squares, triangles, or hexagons.

While the most popular methods of filling in a 3D printed objects do the job of adding a little bit of strength to a print and supporting the top layers of a print, it’s not an ideal solution. The desired strength of the finished part is never taken into account, print artifacts are sometimes visible through the side of a print, and the spacing of the infill grid is completely arbitrary. You can only set a percentage of infill, and telling a slicer to make an internal support grid with 10mm spacing is impossible.

Type A Machines just changed all of this. With the release of their public beta of Cura Type A, the infill for a 3D printed part is also 3D. The dimensions of the infill are predictable, opening the door to stronger and better looking parts.

From the Type A press literature and white paper, this new type of ‘infill’ isn’t; it’s more properly referred to as ‘internal structure’, with proper dimensions between infill features. Instead of a grid of squares or triangles stacked one layer on top of each other, it’s a true structure, with the infill following the perimeter of the 3D printed object.

Generating 3D Infill

Infill generated from Type A Machine’s Cura beta. Note the 3D structure of the infill.

Right now, infill is generated in a slicer by specifying a percentage. Zero percent infill means a hollow object, and 100% infill is a completely solid part. These two edge cases are easy, but anything else means the slicer must fill the part with filament in a grid of tessellating shapes, either rectangles, triangles, or hexagons. With current slicers, the dimensions of this internal structure are, for all practical purposes, random. Printing an object with 20% infill might mean a grid of squares with 5mm or 2mm spacing. Telling the slicer to infill a part with a grid of squares spaced 10mm apart is impossible.

Type A Machine’s latest Cura release changes all of this, allowing a designer to set a precise distance between rows and columns of infill. By defining infill in absolute dimensions, this allows for stronger parts using less infill.

Absolute dimensioning is only one feature of the Type A Machine’s latest release of Cura. Even more exciting is the development of 3D internal structure. Instead of stacking layers of squares, triangles, or hexagons on top of each other, Type A Machine’s Cura uses an infill of cubes turned on their side. While each individual layer of infill looks like a series of triangles and irregular hexagons, when assembled into a printed 3D object, this infill forms a true 3D structure.

The closest comparison to this sort of structure is the difference between graphite and diamond. Both of these materials are made out of the same element, carbon. The physical structure of graphite is just, 1-atom-thick layers of graphene, producing a relatively weak material. Diamond, on the other hand, has a true 3D structure and is one of the hardest materials known to man. While adding 3D structure to the infill of 3D printed objects won’t make the objects any stronger, it will drastically reduce delamination, and be much more resistant to stresses in all three dimensions.

While Type A Machines has done some great work here, it does mean there’s yet another version of Cura to deal with. Type A Machine’s Cura, in addition to the LulzBot edition and the original are now the defacto standard for turning 3D objects into printed parts. Having an open source solution is great, but forking the development this much surely can’t be ideal.

The Dark Arts: Hacking Humans

June 10, 2016 by Will Sweatman 53 Comments

One of the biggest challenges for a company that holds invaluable data is protecting it. At first, this task would seem fairly straightforward. Keep the data on an encrypted server that’s only accessible via the internal network. The physical security of the server can be done with locks and other various degrees of physical security. One has to be thoughtful in how the security is structured, however. You need to allow authorized humans access to the data in order for the company to function, and there’s the rub. The skilled hacker is keenly aware of these people, and will use techniques under the envelope of Social Engineering along with her technical skills to gain access to your data.

Want to know how secure your house is? Lock yourself out. One of the best ways to test security is to try and break in. Large companies routinely hire hackers, known as penetration testers, to do just this. In this article, we’re going to dissect how a hired penetration tester was able to access data so valuable that it could have destroyed the company it belonged to.

Information Gathering

The start of any hack involves information gathering. This is usually pretty easy for larger companies. Their website along with a few phone calls can reveal quite a bit of useful information. However, you can be assured that any company who has hired a pen tester has taken the necessary precautions to limit such information.

And such was the case for our hacker trying to gain access to the ACME Corp. servers. Her first target was the dumpsters – dumpster dives have been proven to unearth a trove of valuable information in the past. But the dumpsters were inside the complex, which was guarded by a contracted security firm. Through a bit of website snooping and a few phone calls, she was able to find out the department that was in charge of trash removal for the company. She then placed a phone call to this department. Using a social engineering (SE) technique known as pretexting, she pretended to be with a trash removal company and wanted to submit a quote to service their business. Using another SE technique called elicitation, she was able to find out:

that trash collection took place on Wednesdays and Thursdays
the total number of dumpsters
that there was a special dumpster for paper and technology trash
the name of the current waste removal company – Waster’s Management
the name of the employee in charge of the waste removal – [Christie Smith]

Dumpster Dive

Armed with this information, she went to the Waster’s Management website and grabbed their JPEG logo. Within a few days, she had a shirt and hat with the logo in her hands. She called the security department and said she was with Waster’s Management, and that [Christie Smith] had told her one of the dumpsters was damaged, and she needed to take a look at it before the next trash removal.

The next day, wearing the shirt and hat she had ordered online, she was given a badge from security and allowed access to the dumpsters. Now, any hacker worth her weight in PIC16F84’s already knows what dumpster she dove into. It didn’t take her long to walk away with several hard drives, a few USB drives and some useful documents. She was able to gain knowledge of an upcoming IT contract work, the name of the CFO, and the name of a server with some level of importance – prod23.

Hacking the Server

With some more SE, she was able to find out when the IT work was scheduled. It was after hours. She showed up a bit late and was able to walk right through the front door by claiming she worked for the IT contract company. She then shifted roles and pretended to be an employee. She approached one the real IT contract guys, and said she worked for the CFO, [Mr. Shiraz], and asked if he knew to be careful with the prod23 server. With more SE, she was able to find out the prod23 server was off-limits, encrypted, and only accessible by specific admins.

She was able to access an admin office, and it was there she would don her black hat. She booted the computer with BackTrack via USB and installed a key logger. She made an SSH tunnel to her personal server where she could dump the contents of the key logger, along with some other shells. Now, this is where things get interesting. She opened Virtual Box and used the computer’s hard drive as the boot medium. The VM booted the OS, and she hid all of the screen decorations to make it look like the target OS was running. The admin would log in without a clue, and our hacker would get their username and password through the key logger.

Once the login information came in, she was able to access the admin’s computer, and from there the prod23 server. You can imagine the look on the faces of the top executives for ACME Corp when our hacker handed them a copy of the keys to their kingdom.

Social engineering is human hacking, and a dark art in itself. Our hacker in this story would have never been able to even get close to the server if she did not have SE skills. No matter how secure you make something, so long as you allow humans access to it, it’s vulnerable to attack. And then it’s down to how well-trained your people are in repelling these kinds of intrusions.Just ask Target.

You can find the full story in the source below.

Sources

Social Engineering, The Art of Human Hacking, Chapter 8, by Christopher Hadnagy, ISBN-13: 860-1300286532

Data Logging; Everyone’s Doing It, Why Aren’t You?

June 9, 2016 by Rud Merriam 35 Comments

Between Tesla Motors’ automobiles and SpaceX’s rockets, Elon Musk’s engineers just have to be getting something right. In part, SpaceX’s success in landing their first stage rockets is due to analysis of telemetry data. You can see some of the data from their launch vehicles on the live videos and there is surely a lot more not shown.

An article in MIT Technology Review provides similar insights in how Tesla came from behind in autonomous vehicle operation by analyzing telemetry from their cars. Since 2014 their Model S received an increasing number of sensors that all report their data over the vehicle’s always-on cellular channel. Sterling Anderson of Tesla reported they get a million miles of data every 10 hours.

The same approach can help us to improve our systems but many believe creating a log of key data is costly in time and resources. If your system is perfect (HA HA!) that would be a valid assessment. All too often such data becomes priceless if analysis explains why your drone or robot wanted to go left into a building instead of right into the open field.

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High Voltage Please, But Don’t Forget The Current

June 8, 2016 by Steven Dufresne 30 Comments

In high voltage applications involving tens of thousands of volts, too often people think about the high voltage needed but don’t consider the current. This is especially so when part of the circuit that the charge travels through is an air gap, and the charge is in the form of ions. That’s a far cry from electrons flowing in copper wire or moving through resistors.

Consider the lifter. The lifter is a fun, lightweight flying machine. It consists of a thin wire and an aluminum foil skirt separated by an air gap. Apply 25kV volts across that air gap and it lifts into the air.

Lifter flying with high voltage power supply

Lifter parts

So you’d think that the small handheld Van de Graaff generator pictured below, that’s capable of 80kV, could power the lifter. However, like many high voltage applications, the lifter works by ionizing air, in this case ionizing air surrounding the thin wire resulting in a bluish corona. That sets off a chain of events that produces a downward flowing jet of air, commonly called ion wind, lifting the lifter upward.

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Stay Scrappy, Hackers! Hardware Startups Versus Goliath

June 7, 2016 by Bob Baddeley 64 Comments

A toast to all the hackers out there who like to do it scrappy, who fight hard to get your products to work, who make your own tools and testing jigs and assembly lines in your basement, and who pound the pavement (and the keyboards) to get your product out there. Here’s to you (*clink*).

I had the fortune of a job interview recently in a big faceless company that you may have never heard of but probably use their stuff all the time. They make billions. And it was surreal. This article is about what it’s like for a scrappy start-up engineer to walk into the belly of the beast of an organization that counts its engineers in the tens of thousands. For obvious reasons, I can’t go into specific details, but let me paint for you in broad strokes what you, the hacker and entrepreneur, are up against.

When you have a company that’s been around for decades and whose yearly sales volume has more digits than some countries, everything is a few orders of magnitude bigger in scale. People, resources, volumes, everything.

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Learn To Program With Literate Programming

June 6, 2016 by Gerrit Coetzee 72 Comments

My heyday in programming was about five years ago, and I’ve really let my skills fade. I started finding myself making excuses for my lack of ability. I’d tackle harder ways to work around problems just so I wouldn’t have to code. Worst of all, I’d find myself shelving projects because I no longer enjoyed coding enough to do that portion. So I decided to put in the time and get back up to speed.

Normally, I’d get back into programming out of necessity. I’d go on a coding binge, read a lot of documentation, and cut and paste a lot of code. It works, but I’d end up with a really mixed understanding of what I did to get the working code. This time I wanted to structure my learning so I’d end up with a more, well, structured understanding.

However, there’s a problem. Programming books are universally boring. I own a really big pile of them, and that’s after I gave a bunch away. It’s not really the fault of the writer; it’s an awkward subject to teach. It usually starts off by torturing the reader with a chapter or two of painfully basic concepts with just enough arcana sprinkled in to massage a migraine into existence. Typically they also like to mention that the arcana will be demystified in another chapter. The next step is to make you play typist and transcribe a big block of code with new and interesting bits into an editor and run it. Presumably, the act of typing along leaves the reader with such a burning curiosity that the next seventeen pages of dry monologue about the thirteen lines of code are transformed into riveting prose within the reader’s mind. Maybe a structured understanding just isn’t worth it.

I wanted to find a new way to study programming. One where I could interact with the example code as I typed it. I wanted to end up with a full understanding before I pressed that run button for the first time, not after.

When I first read about literate programming, my very first instinct said: “nope, not doing that.” Donald Knuth, who is no small name in computing, proposes a new way of doing things in his Literate Programming. Rather than writing the code in the order the compiler likes to see it, write the code in the order you’d like to think about it along with a constant narrative about your thoughts while you’re developing it. The method by which he’d like people to achieve this feat is with the extensive use of macros. So, for example, a literate program would start with a section like this:

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Artificial Muscles To Bring Relief To Robotic Tenseness

June 6, 2016 by Moritz Walter 17 Comments

Custom, robotic prosthesis are on the rise. In numerous projects, hackers and makers have taken on the challenge. From Enabling The Future, Open Hand Project, OpenBionics to the myriad prosthesis projects on Hackaday.io. Yet, the mechatronics that power most of them are still from the last century. At the end of the day, you can only fit so many miniature motors and gears into a plastic hand, and only so many hydraulics fit onto an arm or leg before it becomes a slow, heavy brick – more hindering than helpful. If only we had a few extra of these light, fast and powerful actuators that help us make it through the day. If only we had artificial muscles.

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