The end goal of this giant rapid prototyping machine is to print buildings. We’re not holding our breath for a brand new Flintstones-esque abode, but their whimsical suggesting of printed buildings on the moon seems like science fiction with potential. The machine operates similar to a RepRap but instead of plastic parts, it prints stone by binding sand with epoxy. This method is not revolutionary, but hasn’t really been seen in applications larger than a square meter or so. It’s fun to see the things we dabble in heading for industrial production applications.
Above is a video detailing one method for populating a two sided surface mount PCB. We covered using a stencil to apply solder paste for a PCB a few weeks ago. In the comments there was a debate about the virtue of using stencils as well as a question about how two sided boards are populated. This was a good question because reflowing a board twice can cause components on the underside to fall off.
[Wim L’s] comment mentions that there are a couple of methods for two sided population. In the video you will see that a stencil is not being used, but instead, paste is applied by a pedal actuated syringe. The paste is applied to the underside of the board first, then a teeny dot of epoxy is added to hold the component in place. Each part is then positioned normally and baked in a reflow oven. This process both reflows the solder, and cures the epoxy. When the board is reflowed a second time, the epoxy holds the bottom components in place as the top solder reaches its melting point.
This method of applying solder paste is slower than using a stencil. But if done correctly, every component can get the amount of solder needed.
[Amnon] is learning the hard way that water and electronics don’t always like to play nicely together. He’s been working on creating a swimming fish that uses three servos to flex a sheet of fish-shaped polycarbonate. This photo doesn’t really do the project justice but you can get a better idea of what he’s accomplished by watching the videos after the break.
The three servos along with some distance sensors for obstacle avoidance are all controlled by a PIC 16F877A microcontroller. [Amnon] tried out three different waterproofing methods; coating the device in varnish, dipping it in hot glue, and dipping it in epoxy. The first two resulted in water damage to the electronics, but the third managed to work. It kept the water out, but also prevents reprogramming of the controller.
Although not successful, we would have loved to see the process of dipping the fish in a churning vat of molten glue. Once perfected, this may be the perfect platform for carrying our weapons of doom.
Continue reading “Polycarbonate fish uses three servos to swim”
[fibra] has been slowly building a custom controller for his motorcycle. It’s an automated chain oiling system that varies application based on RPM. The LCD can show wheel RPM, voltage, time, date, air, and engine temperature. A separate driver board has a MOSFET for controlling the oiling valve. The real gold here is the attention to detail. He built a one off circuit board. The case is laser cut acrylic that he then shaped. The box is molded smoothly into the original instrument cluster using epoxy. It’s excellent work that could be mistaken for a commercial product.