Robot Arm Wields Laser, Cares Not For Your Safety

Here at Hackaday we’ve covered a bunch of DIY laser diode projects. And for good reason, they are just cool. We’ve seen people add lasers to their 3D printers, stick one in a milling machine, use a highly modified scanner and even build a simple XY gantry specifically for the task. To say the least there is definitely a wide range of methods for moving around a laser but we’ve never seen anything like what [Sp4rky] sent in to us. He and his friends outfitted an old educational robot arm with a laser.

The robot arm is a 5 axis Armdroid 5100 picked up from eBay for a couple hundred dollars. It didn’t come with a controller but all of the stepper drivers were housed in the base of the arm. After a little tinkering around with the inputs the team was able to get the arm to move by sending serial commands from a PC, through an Arduino Mega which then sends the appropriate signals to the uni-polar stepper drivers. That was the easy part of the build.

The hard part was getting the arm to hold the laser at a consistent angle and height above the table. Inverse Kinematics to the rescue! Since the desired position of the laser, as well as the length of the arm segments is known, mathematical formulas can be derived to determine the necessary arm segment and joint positions while moving the laser around. The process flow starts out with an image in Inkscape, g-code is then generated with this plugin, then sent to the Arduino running a modified version of GRBL that has the inverse kinematic formulas. The Arduino directly controls the stepper drivers and the robotic arm moves. The Arduino also controls 3 constant-current laser drivers made from LM317 regulators. Three laser drivers, why?

Triple Laser Robot[Sp4rky] got his laser diode modules out of surplus medical equipment and, unfortunately, the rated optical wattage was quite low. Since he had 3 diodes, he decided to try to combine the 3 low power beams into one high power beam. This can be done using a prism. A prism splits sunlight it a rainbow of colors because each wavelength(color) of light that passes through the prism is bent a different amount. Since the laser diodes only put out one wavelength of light, the beam bends but does not split or diffuse. A 3D printed bracket points each laser diode at a 3-sided pyramidal prism which sends the combined beam of light straight out the bottom towards the object to be cut or engraved.

This project is cool enough that we would have covered it even if [Sp4rky] wasn’t burning a Hackaday logo. Although it doesn’t hurt for anyone wanting their project to get covered!

Reverse-Engineering a Wireless BBQ Thermometer

[Bob] has his own smoker and loves to barbecue, but doesn’t like spending all day checking on his smoker’s temperature. He thought about building his own wireless thermometer setup, which would have been pretty awesome, but then he had a better idea: why not hack an existing wireless barbecue thermometer? [Bob] purchased an off-the-shelf wireless BBQ thermometer and reverse-engineered its wireless protocol to make his own wireless thermometer setup.

The first problem [Bob] encountered was figuring out the frequency of the transmitter. Thankfully [Bob] had access to a spectrum analyzer, where he discovered the transmitter was running at 433.92MHz (a cheap RTL-SDR dongle would also get the job done). Next, [Bob] started digging into the manufacturer’s FCC filings and found that it actually called out the transmit frequency, which matched the transmit frequency he measured. He also found a ton of other helpful information in the filing, like a block diagram and full transmitter schematic.

[Bob] used a Radiometrix RF module to receive the thermometer’s signal. He hooked up the output to his logic analyzer to start decoding the protocol. After a quick visual analysis, [Bob] found that the signal was a preamble followed 13 bytes of Manchester-encoded data being transmitted at 2kbps. He started collecting data with known temperatures, created a table of the data, and began looking for patterns. After quite a bit of searching [Bob] was successfully able to find and parse the temperature values out of the data stream. [Bob] did a great job of documenting his process and results, so check out his writeup if you want to try it out yourself.

The Raspberry Pi Wearable Revolution

With the human URL [] serving as Chief Creative Director of 3D Systems, and [Martha Stewart] selling her own line of 3D printer filament through MakerBot, more and more celebrities are piling onto the hacker, maker, and DIY revolution. Now, the partnership we’ve all been waiting for: the Raspberry Pi Foundation and [The Artist Formerly Known As Prince_logo] are teaming up to produce a line of Pi-based wearable electronics. The first product from this new, fashionable line of electronics is beyond anything you would expect. It’s called the Raspberry Beret, and it’s shaping up to be a Revolution in wearables.

The wearable Raspberry Beret is exactly what you would expect: a habadasher’s masterpiece that pairs equally well with figure skating costumes and skin-tight cloud print suits. Inside, though, is a new piece of hardware based on the Raspberry Pi compute module. This module includes a Bluetooth module that will sync with any Windows phone. The Raspberry Beret also includes enough sensors that will blow away everything from a Fitbit to the new Apple Watch. The Raspberet will keep track of your heart rate, activity, and exercise routine.

The Raspberry Beret is just the beginning; the Pi Foundation and [The Artist Formerly Known As Prince_logo] are also teaming up with OSH Park to produce a limited, special edition Raspberry Pi 2. This board will be clad in the beautiful OSH Park purple soldermask and sports 4GB of eMMC Flash. This Flash will not be usable; instead it will contain a remastered edition of Purple Rain that will play as a startup chime. There will be no option to skip the chime.


Automated Robotic Target Practice

Fan of shooting things? Jealous of proper shooting ranges? Why not build your own automated target practice rig with a few servos and an ATMega168?

[Cowboy Bob] of Making Stuff decided he needed a practice target, and wanted to make it a bit more interesting than throwing up some beer cans on a fence. He’s created a highly durable 10-target “Robo-Target” which can be remote controlled or automated.  A thick piece of 1/4″ angle steel makes up the main frame of it, so if you’re practicing with hand guns it’ll take the abuse. If you’re just using  an air soft or paintball gun you probably don’t need to make it this beefy.

Five servo motors swing paper five targets back and forth on 3D printed swing arms — and since each target has a front and a back side, it gives you 10 different things to shoot at. In challenge mode it’ll even show you two targets at a time which will require you to quickfire in order to get both!

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20 MPH IKEA Poäng Chair With Aerospace-Inspired Control Panel

Spending time at work sitting on the same drab chair can get boring after a while, even if you’re lucky to use a comfortable recliner. If you want to win the Office Olympics, you need something with a bit of pep. [StuffAndyMakes] wanted to build a completely ridiculous motorized office chair. A couple of years in the making, and he’s ready to unleash the 20 MPH IKEA Poäng chair with aerospace-inspired control panel!

The OfficeChairiot MkII, as he has christened it aptly,  is a motorized IKEA Poäng comfy chair. It uses off-the-shelf scooter parts to roll around : Batteries, motors, chains, sprockets, tires, axles, and  bearings. The OfficeChairiot MkII is basically three main parts – the Chassis, the Control Panel and the comfy chair. One of the main parts of the chassis is the motor controller  – The Dimension Engineering Sabertooth 2×60 motor controller – which is also used in beefy battlebots. It’s capable of carrying 1,000 lbs. of cargo and can feed the drive system up to 60 amps per motor channel .

The brain on the chassis is an Arduino Mega which can be controlled via a hand held remote. The Mega also receives data from various sensors for motor temperature, power wire temperature, ambient air temperature, wheel RPM’s, Accelerometer’s, seat occupancy and GPS data. The firmware is designed to ensure safety. The hand held remote needs to ping the on-board Arduino twice a second. If it doesn’t hear from the Remote for whatever reason, the unit stops and turns off the lights.

The Control Panel is one crazy collection of switches, buttons, displays, a missile switch, a master key switch – in all over 30 switches and buttons. All of the devices on the panel are controlled via a second Arduino Mega, helped by a custom multiplexer board to help connect the large number of devices.

Here are a few more features the OfficeChairiot MkII boasts of :

  • 1.5 Horsepower from two 500W scooter motors
  • 20W stereo and MP3 sound effects
  • Weapons sounds, 15 different fart sounds, car alarm, horns, etc.
  • All LED lighting: Headlights, turn signals, 88 undercarriage RGB LEDs
  • Plenty of homemade PCB’s
  • Custom built aluminum body panels (with help from Local Motors, the people behind the 3D printed car)

Aside from the handcrafted wood chassis and circuits boards and firmware, it’s all off-the-shelf stuff. [StuffAndyMakes] plans on open-sourcing the schematics, C++ code and CAD drawings – so post some comments below to motivate him to do so soon. We’d sure like to see a few more of these being built, so that Office Chair racing becomes a competitive sport. Check out the video after the break.

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Visualizing Digital Logic With EL Wire

[Bob] and [Aubrey] run the System Source Computer Museum a little north of Baltimore, Maryland. For an exhibit, they thought a visual representation of digital logic and came up with a two-bit binary adder. Yes, it’s just a full adder and exactly what you would find somewhere in the second or third chapter of any digital logic textbook. The way they’re illustrating how a full adder works is the killer feature here: they’re using EL wire for all of the wires connecting the gates.

The full adder is implemented with an Arduino Mega, but the interface is the real show here. On the left side of the display there are four illuminated toggle switches that show virtual electrons flowing through EL wires, through gates and finally out to a seven-segment display. The EL wires are controlled with an EL Escudo Dos shield – a good thing, since there are a lot of lines between switches, gates, and outputs.

You can check out [Aubrey]’s demo video that also shows off how they built it below. If you’re around Baltimore, you can check out the display at the museum.

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Poking Around Textiles With Your Multimeter

Looking for a fun wearable electronics project? While you can buy specific fabric and conductive thread for your projects, sometimes you can even find conductive fabric where you might not expect it!

In this latest video by Adafruit, [Becky Stern] goes undercover at a fabrics store with her trusty multimeter to find some new material that can be used for electronics projects! While pickings are slim, she made some useful discoveries — most metallic fabrics aren’t conductive, but some are — You’ll definitely need to take your multimeter with you.

Another funny quirk is that some fabrics are only conductive in one direction! Which could make for a really cool project that seemingly defies conventional wiring — or you can sew a conductive thread perpendicular to the continuity to connect it all together.

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