Better 3D Printing Through Holography

December 16, 2017 by Al Williams 22 Comments

When most of us think about 3D printing, we usually think about a machine that melts plastic filament and extrudes it through a nozzle. But we all know that there are other technologies out there that range from cutting and laminating paper, to printing with molten metal or glass. Many of those are out of range for the common hacker. Probably the second most common method uses photo resin and some light source to build the layers in the resin. Researchers at Lawrence Livermore National Laboratory (LLNL) and several universities are experimenting with a new technique that exposes photo resin using three lasers, printing an entire object at one time. You can see a cube formed using the technique in the video below.

In all fairness, the process really isn’t holography but LLNL refers to it as “hologram-like.” In fact, it appears the lasers project more like an oblique projection (you know, like in drafting) which is considerably simpler. Simple enough, that we can’t help but wonder if the hacker community couldn’t develop machines based on this principle. The key would be arranging for the resin to only cure where laser light overlaps.

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Brute Forcing Passwords With A 3D Printer

December 15, 2017 by Adam Fabio 18 Comments

Many of us use a 4 digit pin code to lock our phones. [David Randolph] over at Hak5 has come up a simple way to use a 3D printer to brute force these passwords. Just about every 3D printer out there speaks the same language, G-code. The same language used in CAD and CNC machines for decades.

[David] placed a numeric keypad on the bed of his printer. He then mapped out the height and positions of each key. Once he knew the absolute positions of the keys, it was easy to tell the printer to move to a key, then press and release. He even created a G-code file which would press every one of the 10,000 4 key pin combinations.

A file this large was a bit unwieldy though, so [David] also created a python script which will do the same thing — outputting the G-code and coordinates to brute force any 4 pin keypad. While a printer is quite a bit slower than Hak5’s own USB Rubber Ducky device (which acts as an automated keyboard), it will successfully brute force a password. Although most phones these days do limit the number of password attempts a user gets.

[David] admits this is probably useless in a clandestine/hacking application, but the video is still a great introduction to G-code and using 3D printers for non-printing functions.

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Thermistors And 3D Printing

December 15, 2017 by Al Williams 24 Comments

I always find it interesting that 3D printers — at least the kind most of us have — are mostly open-loop devices. You tell the head to move four millimeters in the X direction and you assume that the stepper motors will make it so. Because of the mechanics, you can calculate that four millimeters is so many steps and direct the motor to take them. If something prevents that amount of travel you get a failed print. But there is one part of the printer that is part of a closed loop. It is very tiny, very important, but you don’t hear a whole lot about it. The thermistor.

The hot end and the heated bed will both have a temperature sensor that the firmware uses to keep temperatures at least in the ballpark. Depending on the controller it might just do on-and-off “bang-bang” control or it might do something as sophisticated as PID control. But either way, you set the desired temperature and the controller uses feedback from the thermistor to try to keep it there.

If you print with high-temperature materials you might have a thermocouple in your hot end, but most machines use a thermistor. These are usually good to about 300 °C. What got me thinking about this was the installation of an E3D V6 clone hot end into my oldest printer which had a five-year-old hot end in it. I had accumulated a variety of clone parts and had no idea what kind of thermistor was in the heat block I was using.

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How Mini Can A Mini Lamp Be?

December 12, 2017 by Jenny List 4 Comments

If there is one constant in the world of making things at the bench, it is that there is never enough light. With halogen lamps, LEDs, fluorescent tubes, and more, there will still be moments when the odd tiny part slips from view in the gloom.

It’s fair to say that [OddDavis]’ articulated mini lamp will not provide all the solutions to your inadequate lighting woes, as its lighting element is a rather humble example of a white LED and not the retina-searing chip you might expect. The lamp is, after all, an entry in our coin cell challenge, so it hardly has a huge power source to depend upon.

What makes this lamp build neat is its 3D-printed articulated chassis. It won’t replace your treasured Anglepoise just yet, but it might make an acceptable alternative to that cheap IKEA desk lamp. With the coin cell LED you’d be hard pressed to use it for much more than reading even with its aluminium foil reflector, but given a more substantial lighting element it could also become a handy work light.

If 3D printed articulated lamps are your thing, take a look at this rather more sophisticated example.

A Remote Controlled Air-Plane

December 11, 2017 by Brian Benchoff 37 Comments

The Air Hogs Sky Shark was a free-flying model airplane powered by compressed air. When it was released in the late ’90s, it was a fairly innovative toy featuring a strikingly novel compressed air engine made entirely out of injection molded plastic. Sales of these model planes took off, and landed on the neighbor’s roof, never to be seen again.

A few weeks ago, [Tom Stanton] revisited this novel little air-powered motor by creating his own 3D printed copy. Yes, it worked, and yes, it’s a very impressive 3D print. That build was just on a workbench, though, and to really test this air motor out, [Tom] used it to propel a remote-controlled plane through the air.

The motor used for this experiment is slightly modified from [Tom]’s original air-powered motor. The original motor used a standard 3-blade quadcopter prop, but the flightworthy build is using a much larger prop that swings a lot more air. This, with the addition of a new spring in the motor and a much larger air tank constructed out of plastic bottles results in a motor that’s not very heavy but can still swing a prop for tens of seconds. It’s not much, but it’s something.

The airframe for this experiment was constructed using [Tom]’s 3D printed wing ribs, a carbon fiber boom for the tail, and only rudder and elevator controls. After figuring out some CG issues — the motor doesn’t weigh much, and planes usually have big batteries in the nose — the plane flew remarkably well, albeit for a short amount of time.

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Roller Coaster Tycoon IRL

December 10, 2017 by Dan Maloney 13 Comments

Additive manufacturing has come a long way, but surely we’re not at the point where we can 3D-print a roller coaster, right? It turns out that you can, as long as 1/25th scale is good enough for you.

Some people build model railroads, but [Matt Schmotzer] has always had a thing for roller coasters. Not content with RollerCoaster Tycoon, [Matt] decided to build an accurate and working model of Invertigo, a boomerang coaster at King’s Park, the coaster nirvana in Cincinnati, Ohio. Covering a sheet of plywood and standing about 3′ tall, [Matt]’s model recreates the original in painstaking detail, from the supporting towers and bracing to the track sections themselves. It appears that he printed everything in sections just like the original was manufactured, with sections bolted together. Even though all the parts were sanded and vapor smoothed, the tracks themselves were too rough to use, so those were replaced with plastic tubing. But everything else is printed, and everything works. An Arduino Mega controls the lift motors, opens and closes the safety bars on the cars, and operates the passenger gates and drop floor in the station. The video below shows it in action.

Fancy a coaster of your own, but want something a little bigger? We understand completely.

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Making Rubber Stamps With OpenSCAD

December 10, 2017 by Tom Nardi 21 Comments

There’s an old saying that goes “If you can’t beat ’em, join ’em”, but around these parts a better version might be “If you can’t buy ’em, make ’em”. A rather large portion of the projects that have graced these pages have been the product of a hacker or maker not being able to find a commercial product to fit their needs. Or at the very least, not being able to find one that fit their budget.

GitHub user [harout] was in the market for some rubber stamps to help children learn the Armenian alphabet, but couldn’t track down a commercially available set. With a 3D printer and some OpenSCAD code, [harout] was able to turn this commercial shortcoming into a DIY success story.

Rather than having to manually render each stamp, he was able to come up with a simple Bash script that calls OpenSCAD with the “-D” option. When this option is passed to OpenSCAD, it allows you to override a particular variable in the .scad file. A single OpenSCAD file is therefore able to create a stamp of any letter passed to it on the command line. The Bash script uses this option to change the variable holding the letter, renders the STL to a unique file name, and then moves on to the next letter and repeats the process.

This procedural generation of STLs is a fantastic use of OpenSCAD, and is certainly not limited to simple children’s stamps. With some improvements to the code, the script could take any given string and font and spit out a ready to print mold.

With a full set of letter molds generated, they could then be printed out and sealed with a spray acrylic lacquer. A mold release was applied to each sealed mold, and finally they were filled with approximately 200ml of Simpact urethane rubber from Smooth-On. Once the rubber cures, he popped them out of the molds and glued them onto wooden blocks. The end result looks just as good as anything you’d get from an arts and crafts store.

The process used here is very similar to the 3D printed cookie molds we’ve covered recently, though we have to assume these little morsels would not be nearly as tasty. Of course, if you had access to a small CNC machine you could cut the stamps out of the rubber directly and skip the mold step entirely.