Who doesn’t love epoxy? Epoxy resins, also known as polyepoxides, are an essential adhesive in many applications, both industrially and at smaller scales. Many polyepoxides however require the application of heat (around 150 °C for most types) in order to cure (harden), which can be complicated when the resin is applied to or inside layers of temperature sensitive materials. Now researchers at Nanyang Technological University (NTU) in Singapore have found a way to heat up resins using an alternating magnetic field (PDF), so-called magnetocuring.
As detailed in the research article by R. Chaudhary et al., they used commercially available epoxy resin and added nano particles of a MnxZn1-xFe2O4 alloy. This mixture was exposed to an alternating magnetic field to induce currents in the nano particles and subsequently produce heat that served to raise the temperature of the surrounding resin to about 160 °C in five minutes, allowing the resin to cure. There is no risk of overheating, as the nano particles are engineered to reach their Curie temperature, at which point the magnetic field no longer affects them. The exact Curie temperature was tweaked by changing the amount of manganese and zinc in the alloy.
After trying out a number of different alloy formulations, they settled on Mn0.7Zn0.3Fe2O4 as the optimal formulation at which no resin scorching occurred. As with all research it’s hard to tell when (and if) it will make it into commercial applications, but if this type of technology works out we could soon be gluing parts together using epoxy resin and an EM field instead of fumbling with the joys of two-component epoxy.
Hide glue has been around for thousands of years, and some of it is holding wood pieces three thousand years after application. It is made from animal protein, so vegetarians may want to stick to the petroleum-based adhesives. [Surjan Singh] wanted to see if its longevity made it a contender with modern epoxy by casting a couple of fiberglass car parts with the competing glues. In short, it doesn’t hold up in this situation, but it is not without merit.
Musical instrument makers and antique restorers still buy and use hide glue, but you would never expose it to heat or moisture. To its credit, hide glue doesn’t require a ventilator. All you need is boiling water and a popsicle stick, and you are in business. [Surjan] writes his findings like a narrative rather than steps, so his adventures are a delight to read. He found that a car part made with fiberglass and epoxy will withstand the weather better than the alternative because heat and humidity will soften hide glue. His Saab 96 isn’t the right application, but since it is nearly as strong as epoxy once set, you could make other fabric shapes, like a flannel nightstand or a lace coffee table, and you could shape them in the living room without toxifying yourself
No matter how you want to work with glues and substrates, Bil Herd has you covered, and here is an excellent tip for a cheap degassing setup.
While production of the Tesla Cybertruck won’t start production until 2021 (at the earliest), you can always try to build your own. Unless you have a really big spare parts drawer, though, it probably won’t be full sized, but you can at least build a model if you have a shop as well-stocked as [Emiel]. He took some time to build a model cybertruck out of a single sheet of aluminum. (Video, embedded below. You might want to turn on subtitles.)
This project is a great example of the fact that some projects that seem simple on the surface require some specialized tools to get just right. To start, the aluminum sheet was cut with a laser to get into the appropriate shape and include details like windows, and the bending points were marked with an engraver to help the bending process along. The one tool that [Emiel] was missing was a brake, but he got great results with a set of metal bending pliers.
Finishing the model didn’t go particularly smoothly, either. He had planned to braze the metal together, but the heat required kept warping the body panels. The solution was to epoxy it together and sand down the excess, and the results are hopefully stronger than brazing would have been since he added a cloth to the epoxy for extra strength. The windows are made from polycarbonate (and didn’t break during the durability test), and we hope that when [Emiel] is ready to put in a motor he uses one of his custom-built electric motors. Continue reading “The Next Best Thing To A Cybertruck”
Epoxy resins are an important material in many fields. Used on their own as an adhesive, used as a coating, or used in concert with fiber materials to make composites, their high strength and light weight makes them useful in many applications. [Tech Ingredients] decided to explore how combining basic epoxy resin with various additives can make it perform better in different roles.
The video primarily concerns itself with explaining different common additives to epoxy resin mixtures, and how they impact its performance. Adding wood flour is a great way to thicken epoxy, allowing it to form a bead when joining two surfaces. Microbeads are great to add if you’re looking to create a sandable filler. Other additive like metal powders lend the mixture resistance to degradation from UV light, while adding dendritic copper creates a final product with high thermal conductivity.
The video does a great job of not only explaining the additives and their applications, but also shares a few handy tips on best workshop practices. Things like triple-gloving and observing proper mixing order can make a big difference to your workflow and lead to better results.
We’ve seen practical applications of epoxy mixes before – with epoxy granite being a particularly popular material. Video after the break.
Continue reading “Using Additives For Better Performing Epoxy”
Chip decapping videos are a staple of the hacking world, and few things compare to the beauty of a silicon die stripped of its protective epoxy and photographed through a good microscope. But the process of actually opening that black resin treasure chest seems elusive, requiring as it does a witch’s brew of solvents and acids.
Or does it? As [Curious Marc] documents in the video below, a little heat and some finesse are all it takes, at least for some chips. The method is demonstrated by [Antoine Bercovici], a paleobotanist who sidelines as a collector of old chips. After removing chips from a PCB — he harvested these chips from an old PlayStation — he uses hot air to soften the epoxy, and then flexes the chip with a couple of pairs of pliers. It’s a bit brutal, but in most of the Sony chips he tried for the video, the epoxy broke cleanly over the die and formed a cleavage plane that allowed the die to be slipped out cleanly. The process is not unlike revealing fossils in sedimentary rocks, a process that he’s familiar with from his day job.
He does warn that certain manufacturers, like Motorola and National, use resins that tend to stick to the die more. It’s also clear that a hairdryer doesn’t deliver enough heat; when they switched to a hot air rework station, the success rate went way up.
The simplicity of this method should open the decapping hobby up to more people. Whether you just want to take pretty pictures or if reverse engineering is on your mind, put the white fuming nitric acid down and grab the heat gun instead.
Continue reading “Chip Decapping The Easy Way”
A staple of consumer devices for decades, seven segment displays are arguably one of the most recognizable electronic components out there. So it’s probably no surprise they’re cheap and easy to source for our own projects. But that doesn’t mean there isn’t room for personal interpretation.
[MacCraiger] wanted to build a wall clock with the classic seven segment LED look, only his idea was to make it slightly larger than average. With RGB LED strips standing in for individual LEDs, scaling up the concept isn’t really a problem on a technical level; the tricky part is diffusing that many LEDs and achieving the orderly look of a real seven segment display.
All those segments perfectly cut out of a sheet of plywood come courtesy of a CNC router. Once the rectangles had been cut out, [MacCraiger] had to fill them with something that could soften up the light coming from the LEDs mounted behind them. He decided to break up a bunch of glass bottles into small chunks, lay them inside the segments, and then seal them in with a layer of clear epoxy. The final look is unique, almost as though the segments are blocks of ice.
At first glance the use of a Raspberry Pi Zero to control the LED strips might seem overkill, but as it turns out, [MacCraiger] has actually added in quite a bit of extra functionality. The purists might say it still could have been done with an ESP8266, but being able to toss some Python scripts on the Linux computer inside your clock certainly has its appeal.
The big feature is interoperability with Amazon’s Alexa. Once he tells the digital home assistant to set an alarm, the clock will switch over to a countdown display complete with digits that change color as the timer nears zero. He’s also written some code that slowly shifts the colors of the digits towards red as the month progresses, a great way to visualize at a glance how close you are to blowing past that end of the month deadline.
We’ve seen something of a run on custom multi-segment displays recently. Just last month we saw a clock that used some incredible 25-segment LED displays, complete with their own unique take on the on epoxy-filled diffusers.
Continue reading “Huge Seven Segment Display Made From Broken Glass”
Usually corroded buttons on a piece of electronic equipment wouldn’t be that big a deal to repair, but as [Haris Andrianakis] recently found out, things can get a little tricky when they are sealed inside a device meant to operate in a marine environment. Figuring out how to get into the case to clean the buttons up is only half the battle, when you’re done you still need to close it back well enough that the elements can’t get in.
The device in question is a tachometer intended for a Yamaha outboard motor, and the buttons are sealed between the guage’s face and the compartment in the rear that holds the electronics. Pulling the guts out of the back was no problem, but that didn’t get [Haris] any closer to the defective buttons. In light of the cylindrical design of the gauge, he decided to liberate the front panel from the rest of the unit with his lathe.
Removing the face was a delicate operation, to put it mildly. The first challenge was getting the device mounted securely in the chuck, but then the cutting had to be done very carefully so as not to damage the housing. Once he cut through the side far enough to get the face off, the actual repair of the buttons was fairly straightforward. But how to get it back together?
After a few missteps, [Haris] finally found a solution that have him the results he was looking for. He 3D printed a ring that fit the front of the gauge tightly, hot glued it into place, and used it as a mould to pour in black epoxy resin. Once the epoxy had cured, the mould was cut off and the gauge went back on the lathe so he could trim away the excess. He had to do some hand sanding and filing to smooth out the bezel, but overall the end result looks very close to factory.
We get it, there’s a lot to consider when you add a lathe to your workshop. But hacks like these are wonderful reminders of how many tricks these versatile machines are really capable of.
Continue reading “Lathe And 3D Printer Help Repair Buried Buttons”