Stephanie Kwolek: Saving Lives with Kevlar

Almost a really bad day in the woods.

Like most accidents, it happened in an instant that seemed to last an eternity. I had been felling trees for firewood all afternoon, and in the waning light of a cold November day, I was getting ready to call it quits. There was one tiny little white pine sapling left that I wanted to clear, no thicker than my arm. I walked over with my Stihl MS-290, with a brand new, razor sharp chain. I didn’t take this sapling seriously — my first mistake — and cut right through it rather than notching it. The tree fell safely, and I stood up with both hands on the saw. Somehow I lost my footing, swiveled, and struck my left knee hard with the still-running chainsaw. It kicked my knee back so hard that it knocked me to the ground.

In another world, that would likely have a been a fatal injury — I was alone, far from the house, and I would have had mere minutes to improvise a tourniquet before bleeding out. But as fate would have it, I was protected by my chainsaw chaps, full of long strands of the synthetic fiber Kevlar.

The chain ripped open the chaps, pulled the ultrastrong fibers out, and instantly jammed the saw. I walked away feeling very stupid, very lucky, and with not a scratch on me. Although I didn’t realize it at the time,  I owed my life to Stephanie Kwolek.

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Making Prints More Resilient With Fibre-Filled Filament

For all that we love 3D printers, sometimes the final print doesn’t turn out as durable as we might want it to be.

Aiming to mimic the properties of natural structures such as wood, bone, and shells, a research team lead by [Jennifer A. Lewis] at Harvard John A. Paulson School of Engineering and Applied Sciences’ Lewis Lab have developed a new combined filament and printing technique which they call rotational 3D printing.

Minuscule fibres are mixed in with the epoxy filament and their controlled orientation within the print can reinforce the overall structure or specific points that will undergo constant stresses. To do so the print head is fitted with a stepper motor, and its precisely programmed spin controls the weaving of the fibres into the print. The team suggests that they would be able to adapt this tech to many different 3D printing methods and materials, as well as use different materials and printed patterns to focus on thermal, electrical, or optical properties.

Be it adding carbon nano-tubes or enlisting the expertise of spiders to refine our printed materials, we’re looking forward to the future of ever stronger prints. However, that doesn’t mean that existing methods are entirely lacking in endurance.

[Thanks for the tip, Qes!]

Behind the Scenes at a Pair of Cell Sites

Those who fancy themselves as infrastructure nerds find cell sites fascinating. They’re outposts of infrastructure wedged into almost any place that can provide enough elevation to cover whatever gap might exist in a carrier’s coverage map. But they’re usually locked behind imposing doors and fences with signs warning of serious penalty for unauthorized access, and so we usually have to settle for admiring them from afar.

Some folks, like [Mike Fisher] aka [MrMobile], have connections, though, and get to take an up close and personal tour of a couple of cell sites. And while the video below is far from detailed enough to truly satisfy most of the Hackaday crowd, it’s enough to whet the appetite and show off a little of what goes into building out a modern cell site. [Mike] somehow got AT&T to take him up to a cell site mounted in the belfry and steeple of the 178-year old Unitarian Church in Duxbury, Massachusetts. He got to poke around everything from the equipment shack with its fiber backhaul gear and backup power supplies to the fiberglass radome shaped to look like the original steeple that now houses the antennas.

Next he drove up to Mount Washington in New Hampshire, the highest point in the northeast US and home to a lot of wireless infrastructure. Known for having some of the worst weather in the world and with a recent low of -36°F (-38°C) to prove it, Mount Washington is brutal on infrastructure, to which the tattered condition of the microwave backhaul radomes attests.

We appreciate the effort that went into this video, but again, [Mike] leaves us wanting more details. Luckily, we’ve got an article that does just that.

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Vacuum Molding with Kitchen Materials

Vacuum pumps are powerful tools because the atmospheric pressure on our planet’s surface is strong. That pressure is enough to crush evacuated vessels with impressive implosive force. At less extreme pressure differences, [hopsenrobsen] shows us how to cleverly use kitchen materials for vacuum molding fiberglass parts in a video can be seen after the break. The same technique will also work for carbon fiber molding.

We’ve seen these techniques used with commercially available vacuum bags and a wet/dry vac but in the video, we see how to make an ordinary trash bag into a container capable of forming a professional looking longboard battery cover. If the garbage bag isn’t enough of a hack, a ball of steel wool is used to keep the bag from interfering with the air hose. Some of us keep these common kitchen materials in the same cabinet so gathering them should ’t be a problem.

Epoxy should be mixed according to the directions and even though it wasn’t shown in the video, some epoxies necessitate a respirator. If you’re not sure, wear one. Lungs are important.

Fiberglass parts are not just functional, they can be beautiful. If plastic is your jam, vacuums form those parts as well. If you came simply for vacuums, how about MATLAB on a Roomba?

Thank you [Jim] who gave us this tip in the comments section about an electric longboard.

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Hackaday Prize Entry: An Optical Power Meter

This is the type of crowd that’s famous for building their own test equipment. If you need a way to program a flash chip, don’t go out and buy one — you can just build one. Need a spectrum analyzer? You can build that out of copper clad board. For his Hackaday Prize entry, [oakkar7] is building an optical power meter, capable enough to do futzy fiber work, but still completely DIY.

When you get into networking and telecom connections that don’t begin with the letters ‘RJ’, you start to stumble upon SPF transceivers. These ‘small form factor pluggable’ devices are little modular transceivers capable of handling fiber, Gigabit Ethernet, and other slightly weirder bit pipes. When used with fiber, they can measure optical power in dBm and watts, and can be debugged by a UART.

[oakkar]’s optical power meter uses these SPF transceivers, tied together with a fairly simple circuit consisting of an Arduino, a few tact switches, a Nokia LCD, and an FTDI UART. The key in tying all of this together is an Arduino library for SPF and DDM (Digital Diagnostics Monitoring), giving the user access to all the configuration bits in these transceivers.

While the circuit is simple enough to be built on a piece of perfboard, [oakkar] really knocked it out of the park with the enclosure on this one. With just a little bit of laser cut acrylic and a few standoffs, [oakkar] has a device that actually looks professional, and has most of the capabilities of fancier, more expensive tools.

Victorians and Fiber, Louisville’s Quest For Fast Internet

It was a dark and stormy afternoon, the kind you get on the east side of the country. I was drinking a coffee, sitting in a camping chair in front of my door, and watching like a hawk for the treacherous cable man to show up. This day there would be no escape. There would be no gently rapping the door with a supple sheepskin leather glove before scurrying away for another union mandated coffee break. I was waiting, I was kind of grumpy, and by God today would be the day. Today would be the day that after hours on hold, after three missed appointments, after they lost my records twice; I would get an answer on whether or not they could actually service internet to my apartment. If I was lucky, and the answer was yes, then approximately two to three thousand years later they would run a cable from the telephone pole to my house and I could stop commandeering WiFi from the pizza shop across from me.

It’s important to note that I was in the middle of the city. I wasn’t out in the boonies. Every house on the block but mine had cable. While this is dumb, it begins to make more sense when you dive into the history. Louisville, Kentucky is a strange place. It used to be the gateway to the west. Ships would crawl up its river until they reached the falls. Then porters would charge an exorbitant fee to carry all those goods down to the bottom of the falls where they would be loaded on a ship and be sent ever westward. Resulting in every rich merchant, captain, and manufacturer in the region having a nice house there. Ever wonder why the Derby is in Louisville and the Queen comes to visit sometimes? It probably has something to do with it having the highest concentration of Victorian buildings and mansions outside of New York City.

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Ethernet over telephone wire

When [Bobo1on1] upgraded his Internet connection from ADSL to Fiber he ran into an issue of actually getting that speed to his desktop computer though his LAN setup. Before he had been using a telephone extension wire which ran from where the DSL entered the house, through a splitter, to his computer where the modem was located. Now that the router used by the fiber system is located at teh entry point, he has no easy way to run Ethernet cable to his computer room. Wifi is predictably slower than the 50mbit WAN connection, and he was unable to use the telephone cable as Ethernet directly.

The solution turns out to be a pair of TP-Link home plug adapters. These are designed to use your home’s mains wiring for data transfer. But [Bob] rigged it up so that they can push 224 mbits/sec over the telephone wire. Since you can’t run mains voltage through the telephone wire he had to hack a method to separate power for the devices from the data I/O. This was done with an external power supply and some passive components for filtering. The drawback is that this is half-duplex so up/down communications cannot happen at the same time.