Robot Arm Wields Laser, Cares Not For Your Safety

April 1, 2015 by Rich Bremer 44 Comments

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?

[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 into 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

April 1, 2015 by Ethan Zonca 11 Comments

[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

April 1, 2015 by Brian Benchoff 44 Comments

With the human URL [will.i.am] 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 ] 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 ] 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.

Pancakes.

Automated Robotic Target Practice

April 1, 2015 by James Hobson 12 Comments

Fan of shooting things? Jealous of proper shooting ranges? Why not build your own automated target practice rig (link dead, try the Internet Archive) 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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