Lost PLA Casting With A Little Help From Your Microwave

August 20, 2014 by Adam Fabio 45 Comments

lost-pla

[Julia and Mason] have been perfecting their microwave-based lost PLA casting technique over at Hackaday.io. As the name implies, lost PLA is similar to lost wax casting techniques. We’ve covered lost PLA before, but it always involved forges. [Julia and Mason] have moved the entire process over to a pair of microwaves.

Building on the work of the FOSScar project, the pair needed a way to burn the PLA out of a mold with a microwave. The trick is to use a susceptor. Susceptors convert the microwave’s RF energy into thermal energy exactly where it is needed. If you’ve ever nuked a hot pocket, the crisping sleeve is lined with susceptor material. After trying several materials, [Julia and Mason] settled on a mixture of silicon carbide, sugar, water, and alcohol for their susceptor.

The actual technique is pretty simple. A part printed in PLA is coated with susceptor. The part is then placed in a mold made of plaster of paris and perlite. The entire mold is cooked in an unmodified household microwave to burn out the PLA.

A second microwave with a top emitter is used to melt down aluminum, which is then poured into the prepared mold. When the metal cools, the mold is broken away to reveal a part ready to be machined.

We think this is a heck of a lot of work for a single part. Sometimes you really need a metal piece, though. Until metal 3D printing becomes cheap enough for everyone to do at home, this will work pretty well.

TFT LCDs Hit Warp Speed With Teensy 3.1

August 18, 2014 by Adam Fabio 39 Comments

[Paul Stoffregen], known as father of the Teensy, has leveraged the Teensy 3.1’s hardware to obtain some serious speed gains with SPI driven TFT LCDs. Low cost serial TFT LCDs have become commonplace these days. Many of us have used Adafruit’s TFT LCD library to drive these displays on an Arduino. The Adafruit library gives us a simple API to work with these LCDs, and saves us from having to learn the intricacies of various driver chips.

[Paul] has turbocharged the library by using hardware available on Teensy 3.1’s 32 Freescale Kinetis K20 microcontroller. The first bump is raw speed. The Arduino’s ATmega328 can drive the SPI bus at 8MHz, while the Teensy’s Kinetis can ramp things up to 24MHz.

Speed isn’t everything though. [Paul] also used the Freescale’s 4 level FIFO to buffer transfers. By using a “Write first, then block until the FIFO isn’t full” algorithm, [Paul] ensured that new data always gets to the LCD as fast as possible.

Another huge bump was SPI chip select. The Kinetis can drive up to 5 SPI chip select pins from hardware. The ATmega328 doesn’t support chip selects. so they must be implemented with GPIO pins, which takes even more time.

The final result is rather impressive. Click past the break to see the ATmega based Arduno race against the Kinetis K20 powered Teensy 3.1.

Paul’s library is open source and available on Github.

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Hacklet #11- Cameras

August 15, 2014 by Adam Fabio 22 Comments

We preempt this week’s Hacklet to bring you an important announcement.

Hackaday.io got some major upgrades this week. Have you checked out The Feed lately? The Feed has been tweaked, tuned, and optimized, to show you activity on your projects, and from the hackers and projects you follow.

We’ve also rolled out Lists! Lists give you quick links to some of .io’s most exciting projects. The lists are curated by Hackaday staff. We’re just getting started on this feature, so there are only a few categories so far. Expect to see more in the coming days.

Have a suggestion for a list category? Want to see a new feature? Let us know!

Now back to your regularly scheduled Hacklet

There are plenty of cameras on Hackaday.io, from complex machine vision systems to pinhole cameras. We’re concentrating on the cameras whose primary mission is to create an image. It might be for art, for social documentation, or just a snapshot with friends.

[theschlem] starts us off with Pinstax, a 3D Printed Instant Pinhole Camera. [theschlem] is using a commercial instant film camera back (the back for a cheap Diana F+) and 3D printing his own pinhole and shutter. He’s run into some trouble as Fuji’s instant film is fast, like ISO 800 fast. 3 stops of neutral density have come to the rescue in the form of an ND8 filter. Pinstax’s pinhole is currently 0.30mm in diameter. That translates to just about f/167. Nice!

Next up is [Jimmy C Alzen] and his Large Format Camera. Like many large format professional cameras, [Jimmy’s] camera is designed around a mechanically scanned linear sensor. In this case, a TAOS TSL1412S. An Arduino Due runs the show, converting the analog output from the sensor to digital values, stepping the motor, and displaying images in progress on an LCD. Similar to other mechanically scanned cameras, this is no speed demon. Images in full sunlight take 2 minutes. Low light images can take up to an hour to acquire.

[Jason’s] Democracycam aims to use open source hardware to document protests – even if the camera is confiscated. A Raspberry Pi, Pi Cam module, and a 2.8″ LCD touchscreen make up the brunt of the hardware of the camera. Snapping an image saves it to the SD card, and uses forban to upload the images to any local peers. The code is in python, and easy to work with. [Jason] hopes to add a “panic mode” which causes the camera to constantly take and upload images – just in case the owner can’t.

The venerable Raspberry Pi also helps out in [Kimondo’s] Digital Holga 120d. [Kimondo’s] fit a Raspberry Pi model A, and a Pi camera, into a Holga 120D case. He used the Slice of pi prototype board to add a GPIO for the shutter release button, a 4 position mode switch, and an optocoupler for a remote release. [Kimondo] even added a filter ring so he can replicate all those instagram-terrific filters in hardware. All he needs is to add a LiPo battery cell or two, a voltage regulator, and a micro USB socket for a fully portable solution.

Finally, we have [LeoM’s] OpenReflex rework. OpenReflex is an open source 3D printed Single Lens Reflex (SLR) 35mm film camera. Ok, not every part is 3D printed. You still need a lens, a ground glass screen, and some other assorted parts. OpenReflex avoids the use of a pentaprism by utilizing a top screen, similar to many classic twin lens reflex cameras. OpenReflex is pretty good now, but [Leo] is working to make it easier to build and use. We may just have to break out those rolls of Kodachrome we’ve been saving for a sunny day.

That’s it for this week’s Hacklet! Until next week keep that film rolling and those solid state image sensors acquiring. We’ll keep bringing you the best of Hackaday.io!

DIY Custom Molded Earbud Roundup

August 13, 2014 by Adam Fabio 38 Comments

Headphones have become ubiquitous these days. Thanks to the iPod and the smartphone, it’s become commonplace to see someone wearing a pair of earbud style headphones. Earbuds aren’t always comfortable though. On some people they are too loose. On others, the fit is so tight that they cause pain.To that end, we’ve found a few great solutions for this problem.

[cptnpiccard] has documented his custom molded Sugru earbuds in an Imgur gallery. He’s molded a pair of standard earbuds into a cast of his ear. He uses them both for hearing protection and tunes while skydiving. Sugru’s FAQ states that while the cured material is safe for skin contact (and in ear use) some people are sensitive to the uncured material.

While discussing his project on Reddit, a few users chimed in and mentioned they’ve made custom molded earbuds using Radians custom earplug kits. The Radians material hardens up in only 10 minutes, which beats waiting an hour for Sugru.

The absolute top of the food chain has to be building your own triple driver in ear monitors, which is exactly what [marozie] has done. Professional custom molded monitors can cost over $1000, which puts them in the realm of professional musicians and audiophiles. [marozie] discovered that mouser stocks quite a few transducers from Knowles. These tiny speakers don’t come cheap, though; you can spend upwards of $70 just for a single driver.

[marozie] took a cast of his ear using an earmold impression kit. He used this cast to create a mold. From there it was a matter of pouring resin over his carefully constructed driver circuits and audio tubes. The resulting monitors look and sound incredible.

It goes without saying that making custom in ear monitors involves putting chemicals into you ears. The custom earmold kits come with tiny dams to keep the mold material from going in too far and causing damage. This is one of those few places where we recommend following the instructions. Click past the break to see a demo video of the ear molding process.

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Hyperlapse Makes Your HeadCam Videos Awesome

August 12, 2014 by Adam Fabio 34 Comments

hyperlapse First person video – between Google Glass, GoPro, and other sports cameras, it seems like everyone has a camera on their head these days. If you’re a surfer or skydiver, that might make for some awesome footage. For the rest of us though, it means hours of boring video. The obvious way to fix this is time-lapse. Typically time-lapse throws frames away. Taking 1 of every 10 frames results in a 10x speed increase. Unfortunately, speeding up a head mounted camera often leads to a video so bouncy it can’t be watched without an air sickness bag handy. [Johannes Kopf], [Michael Cohen], and [Richard Szeliski] at Microsoft Research have come up with a novel solution to this problem with Hyperlapse.

Hyperlapse photography is not a new term. Typically, hyperlapse films require careful planning, camera rigs, and labor-intensive post-production to achieve a usable video. [Johannes] and team have thrown computer vision and graphics algorithms at the problem. The results are nothing short of amazing.

The full details are available in the team’s report (35MB PDF warning). To obtain usable data, the fisheye lenses often used on these cameras must be calibrated. The team accomplished that with the OCamCalib toolbox. Imported video is broken down frame by frame. Using structure from motion algorithms, hyperlapse creates a 3D models of the various scenes in the video. With the scenes in this virtual world, the camera can be moved and aimed at will. The team’s algorithms then pick a smooth path that follows the original cameras trajectory. Once the camera’s position is known, it’s simply a matter of rendering the final video.

The results aren’t perfect. The mountain climbing scenes show some artifacts caused by the camera frame rate and exposure changing due to the varied lighting conditions. People appear and disappear in the bicycling portion of the video.

~~One thing the team doesn’t mention is how long the process takes~~. We’re sure this kind of rendering must require some serious time and processing power. Still, the output video is stunning.

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Commodore 1530 Datasette Gets A Digital Counter

August 9, 2014 by Adam Fabio 25 Comments

Ah, the humble Commodore 1530 Datasette drive. It never enjoyed much popularity in the USA, but it was the standard for quite some time in Europe. [DerSchatten13] still uses and loves his 1530. When a co-worker showed him some 7-segment bubble LEDs, he knew what he had to do. Thus the 1530 digital counter (translated) was born.

[DerSchatten13] started out by building his design on a breadboard. He used every I/O pin on an ATtiny2313 to implement his circuit. Tape motion is detected by a home-made rotary encoder connected to the original mechanical counter’s belt drive. To keep the pin count down, [DerSchatten13] multiplexed the LEDs on the display.

Now came the hard part, tearing into the 1530 and removing the mechanical counter. [DerSchatten13] glued in some standoffs to hold the new PCB. After rebuilding the circuit on a piece of perfboard, he installed the new parts. The final result looks great on the inside. From the outside, one would be hard pressed to tell the digital counter wasn’t original equipment.

Operation of the digital counter is identical to the analog unit – with one exception. The clear button now serves double duty. Pressing and holding it saves the current count. Save mode is indicated by turning on the decimal point. If the user rewinds the tape, the counter will stop the motor when the saved count is reached. Cueing up that saved program just got a heck of a lot easier!

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Hacklet #10 Cryptography And Reverse Engineering

August 8, 2014 by Adam Fabio 25 Comments

In honor of DEFCON, this week we’re looking at some cryptography and reverse engineering projects over at Hackaday.io Every hacker loves a hardware puzzle, and [Tom] has created a tool to make those puzzles. His Hardware Reverse Engineering Learning Platform consists of a shield with two ATmega328 chips and an I2C EEPROM. The two Atmel chips share a data bus and I2C lines. Right in the middle of all this is an ST Morpho connector, which allows an ST Nucleo board to act as a sniffer. The platform allows anyone to create a reverse engineering challenge! To successfully reverse engineer a board, it sure helps to have good tools. [coflynn] is giving that to us in spaces with The ChipWhisperer. ChipWhisperer is an open source security research platform. The heart of the system is a Xilinx Spartan 6 FPGA. The FPGA allows very high speed operations for things like VCC and clock glitching. ChipWhisperer is an entire ecosystem of boards – from LNA blocks to field probes. The entire system is controlled from an easy to use GUI. The end result is a powerful tool for hardware attacks. On the Encryption side of the house, we start by keeping the Feds at bay. The [Sector67] hackerspace has collectively created NSA AWAY. NSA AWAY is a simple method of sending secure messages over an insecure medium – such as email. A one-time use pad is stored on two SD cards, which are used by two Android devices. The message sender uses an Android device to encrypt the message. On the receive side, the message can be decoded simply by pointing an android device’s camera at the encrypted data. So easy, even a grandparent could do it! Next up is [Josh’s] Bury it under the noise floor. “Bury it” is an education for cryptography in general, and steganographic software in particular. [Josh] explains how to use AES-256 encryption, password hashing, and other common techniques. He then introduces steganography by showing how to hide an encrypted message inside an image. Anyone who participated in Hackaday’s ARG build up to The Hackaday Prize will recognize this technique. [yago] gives us encrypted voice communications with his ZRTP Hardphone. The hardphone implements the ZRTP, a protocol for encrypted voice over IP communications. The protocol is implemented by a Raspberry Pi using a couple of USB sound cards. User interface is a 16×2 Line character LCD, a membrane keypad, and of course a phone handset. Don’t forget that you need to build two units,or whoever you’re trying to call will be rather confused!

Finally we have the Mooltipass. Developed right here on Hackaday by [Mathieu Stephan] and the community at large, Mooltipass is a secure password storage system. All your passwords can be stored fully AES-256 encrypted, with a Smart Card key. Under the hood, Mooltipass uses an Arduino compatible ATmega32U4 microcontroller. UI is through a OLED screen and touch controls. That’s it for this week! Be sure to check out next week’s Hacklet, when we bring you more of the best from Hackaday.io!