Plastic milk bottles, when your project or prototype needs an urgent source of plastic, they are often the first thing to hand. Convenient and flexible, but strong at the same time and usually free, they’re the ultimate source of material in a pinch. However, when it comes to actually manipulating the HDPE plastic they’re made from, there’s often a challenge. It’s easy to cut, but not so easy to join. Conventional glues can have a hard time, making it difficult to bond.
Enter [zimitt], and a spot welding solution for joining HDPE with ease. Ok, so ‘spot welding’ might be a little optimistic given the speed of this process, but it’s useful nonetheless. To heat the plastic, a cheap soldering iron is recommended. A low wattage, straight-to-the-wall one does well, especially as they commonly have the washer-style end shown in the picture. To protect the plastic from burning, a BBQ mat is used – they’re temperature resistant and usually made with a PTFE surface.
First, place the two sheets of plastic face to face and sandwich top and bottom with the BBQ mat. Apply some heat to the mat with the soldering iron then, after a few seconds, remove the iron and provide pressure with a flat object to bond the plastic. [zimitt] used an espresso tamper for this which was ideal.
The results are impressive, and [zimitt] experiments with different plastics as well. Of course, you should exercise caution when attempting anything like this, given the health risks present when heating up different types of plastic.
HDPE is easy to recycle at home, and we’ve seen a lot of great uses: a plastic joiner’s mallet, plastic tiles, and even a filament extruder for 3D printing.
Boston Dynamics, the lauded robotics company famed for its ‘Big Dog’ robot and other machines which push mechanical dexterity to impressive limits have produced a smaller version of their ‘Spot’ robot dubbed ‘SpotMini’.
A lightweight at 55-65 lbs, this quiet, all-electric robot lasts 90 minutes on a full charge and boasts partial autonomy — notably in navigation thanks to proprioception sensors in the limbs. SpotMini’s most striking features are its sleek new profile and manipulator arm, showing off this huge upgrade by loading a glass into a dishwasher and taking out some recycling.
Robots are prone to failure, however, so it’s good to know that our future overlords are just as susceptible to slipping on banana peels as we humans are.
Continue reading “SpotMini Struts Its Stuff”
[Nate] over at Sparkfun put up a great tutorial for using the SPOT personal satellite communicator with just about any microcontroller. These personal satellite transmitters were originally intended to pair with the bluetooth module of a smart phone, allowing you to send a short 41-character message from anywhere in the world. Now, you can use these neat little boxes for getting data from remote sensors, or even telemetry from a weather balloon.
[Nate]’s teardown expands on [natrium42/a>] and [Travis Goodspeed]’s efforts in reverse-engineering the SPOT satellite communicator. The hardware works with the Globalstar satellite constellation only for uplink use. That is, you can’t send stuff to a remote device with a SPOT. After poking around the circuitry of the original, first-edition SPOT, [Nate] pulled out a much cheaper SPOT Connect from his bag of tricks. Like the previous hacks, tying into the bluetooth TX/RX lines granted [Nate] full access to broadcast anything he wants to a satellite sitting in orbit.
We’ve seen the SPOT satellite messaging service put to use in a high altitude balloon over the wilds of northern California where it proved to be a very reliable, if expensive, means of data collection. Sometimes, though, XBees and terrestrial radio just aren’t good enough, and you need a satellite solution.
The SPOT satellite service has an enormous coverage area, seen in the title pic of this post. The only major landmasses not covered are eastern and southern Africa, India, and the southern tip of South America. If anyone out there wants to build a transatlantic UAV, SPOT, and [Nate]’s awesome tutorial, are the tools to use.
Tip ‘o the hat to [MS3FGX] for sending this one in.
[Travis Goodspeed] wrote in to tell us about his work reverse engineering the Bluetooth communications on this SPOT module. He’s targeted the post as a general guide to sniffing Bluetooth transmissions, but was inspired to use the SPOT as an example after seeing this other SPOT hack. We know he’s a fan of getting things to work with his Nokia N900, and that’s exactly where he ended up with the project.
This module was manufactured to be controlled by an Android phone. But there’s no control app available for the Nokia handset. Since Android uses the open-source Bluez package for the Bluetooth protocol, it’s actually pretty easy to get your hands on the packets. After grabbing a few test sets he shows how he deciphered the packets, then wrote a quick Python script to test out his findings. After working his way through the various commands available (grabbing the SPOT serial number, getting position data from it, etc) [Travis] wrote up a frontend in QT mobility for use on the N900.
For less than $100 you can buy a little tracking module that will upload your location to a satellite. But you’ll only get latitude and longitude information. [Natrium42] spent some time reverse engineering the hardware, and the communications protocol, to allow custom data to be transferred using a SPOT module.
The flat fee for the hardware includes a one-year service plan allowing you to tack your device on the SPOT website. [Natrium42] started poking around in the transmitted data packages, and figured he could push custom messages like altitude data if he had some way to encode it as a valid latitude/longitude package. He found that location data is transmitted as two sets of three bytes each. The four least significant bits of each set get rounded by the server, leaving a total of 40 usable bits between the two data sets. He wrote encoding and decoding functions that will allow you to transfer whatever information you want.
So what is this good for? To get the process working he removed the MSP430 microcontroller from the board and is using his own replacement. So you can transmit GPS data from the onboard module, your own module, or sensor data for anything you’re able to hook up the to the replacement uC.
This is the Pinta, an autonomous sailboat built to attempt an ocean crossing from Ireland to Martinique (in the Caribbean). A group of researchers at Aberystwyth University built her as part of the Microtransat Challenge.
To keep tabs on the vessel her creators included an Iridium short burst data modem with a backup system made from a SPOT satellite tracker using a PIC microcontroller to trigger a transmission every six hours. The sailing systems are a conglomeration of a Gumstix board, GPS, a windshield wiper motor to control the sail, and a tiller pilot for steering. A set of solar panels helps to top off the lead-acid batteries that power the system.
Unfortunately the old gal has encountered problems. You can see from the tracking data that, although it sailed 500 km in the last twelve days, she is still just off the coast of Ireland. The primary tracking system has failed, which could signal a system-wide computer failure. We hope the team will eventually recover the vessel as we’re interested in finding out what caused this unfortunate turn of events.
[Fritz] built this 600 joule capacitive discharge spot welder in a case scavenged from a Lincoln plasma cutter. All of the circuitry was designed by [Fritz] and the schematics are available on his website. He has a few other welding related project also documented on his site that are worth checking out. While this isn’t the first homemade spot welder we have seen, it is definitely the first one with a case mod. If you are not up to the challenge of building one quite as complex as [Fritz]’s example, a microwave can be used as the donor appliance in simpler designs.