The Nuts And Bolts Of Nuts And Bolts

If you’re a mechanical engineer, the material covered in this video on the basics of bolted joints probably won’t cover any new ground. On the other hand, if you aren’t a mechanical engineer but still need to bring a little of that discipline to your projects, there’s a lot to learn here.

If there’s one takeaway lesson from [The Efficient Engineer]’s excellent examination of the strength of bolted joints, it’s the importance of preload. Preload is the tensile force created by tightening a bolt or a screw, which provides the clamping force that keeps the joined members together. That seems pretty self-obvious, but there’s more to the story, especially with joints that are subject to cycles or loading and unloading. Such joints tend to suffer from fatigue failure, but proper preloading on the bolts in such a joint mitigates fatigue failure because the bolts are only taking up a small fraction of the total cyclical force on the joint. In other words, make sure you pay attention to factory torque specs.

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Building A Receiver With The ProgRock2 Programmable Crystal

Crystals are key to a lot of radio designs. They act as a stable frequency source and ensure you’re listening to (or transmitting on) exactly the right bit of the radio spectrum. [Q26] decided to use the ProgRock2 “programmable crystal” to build a receiver that could tune multiple frequencies without the usual traditional tuning circuitry. 

 The ProgRock2 is designed as a tiny PCB that can be dropped into a circuit to replace a traditional crystal. The oscillators onboard are programmable from 3.5KHz to 200 MHz, and can be GPS discliplined for accuracy. It’s programmable over a micro USB pot, and can be set to output 24 different frequencies, in eight banks of three. When a bank is selected, the three frequencies will be output on the Clock0, Clock1, and Clock2 pins.There was some confusion regarding the bank selection on the ProgRock2. It’s done by binary, with eight banks selected by grounding the BANK0, BANK1, and BANK2 pins. For example, grounding BANK2 and BANK0 would activate bank 5 (as 101 in binary equals 5). Once this was figured out, [Q26] was on top of things.

In his design, [Q26] hooked up the ProgRock2 into his receiver in place of the regular crystal. Frequency selection is performed by flipping three switches to select banks 0 to 7. It’s an easy way to flip between different frequencies accurately, and is of particular use for situations where you might only listen on a limited selection of amateur channels.

For precision use, we can definitely see the value of a “programmable crystal” oscillator like this. We’ve looked at the fate of some major crystal manufacturers before, too. Video after the break.

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Soldering Station Designed Around Batteries

Companies now are looking to secure revenue streams by sneakily locking customers into as many recurring services as possible. Subscription software, OS ecosystems, music streaming, and even food delivery companies all want to lock consumers in to these types of services. Battery-operated power tools are no different as there’s often a cycle of buying tools that fit one’s existing batteries, then buying replacement batteries, ad infinitum. As consumers we might prefer a more open standard but since this is not likely to happen any time soon, at least we can build our own tools that work with our power tool brand of choice like this battery-powered soldering station. Continue reading “Soldering Station Designed Around Batteries”

Auto Tape Wrapping Machine Is Amazing For Cable Management

If you’ve dived under the hood of any car built in the last 40 years, you’ve likely noticed the bundles of neatly-wrapped cables making up the car’s wiring loom. [The Q] has built a tool for handling jobs like this yourself.

The build starts with a pair of sprockets linked up with bicycle chain, and mounted to a wooden frame. A motor drives the smaller sprocket, which turns the larger sprocket in turn. The larger sprocket itself is mounted on a series of internal rollers, while it mounts a carrier for a roll of tape. As the larger sprocket turns, it will happily wrap whatever you feed through the central hole in tape in a neat and tidy manner.

For those working with automotive looms, large robot cable runs, or PC builds, a tool like this can be of great utility. [The Q} even demonstrates it put to oddball tasks, like wrapping bicycle handlebars or pipe threads. We’ve seen similar builds before, too. Video after the break.

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LED Matrix Displays Get New Look Thanks To SMD Stencils

Even if surface-mount skills aren’t in your repertoire, chances are pretty good that most of us are at least familiar with SMD stencils. These paper-thin laser-cut steel sheets are a handy way to apply a schmear of solder paste to the pads of a PCB before component placement and reflowing. But are stencils good for anything else?

It turns out they are, if you’ve got some plain old 8×8 LED matrix displays you want to jazz up a bit. In this case, [upir]’s displays were of the square pixel type, but this trick would work just as well for a matrix with circular elements. Most of the video below is a master class in Adobe Illustrator, which [upir] used to generate the artwork for his stencils. There are a lot of great tips here that make creating one simple shape and copying it over the whole array with the proper spacing a lot easier. He also details panelizing multiple stencils, as well as the workflow from Illustrator to manufacturing.

When lined up properly over the face of the LED matrix, the stencils have quite an effect. We really liked the narrow vertical bars, which make the LED display look a bit like a VFD. And just because [upir] chose to use the same simple shape over all the LEDs in a matrix doesn’t mean that there aren’t other options. We can see how you might use the same technique to create different icons or even alphanumeric characters to create custom LED displays. The possibilities are pretty much limited to your imagination.

This isn’t the first time we’ve seen [upir] teaching old displays new tricks.

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Rising To The Occasion: A Brief History Of Crewed High Altitude Balloons

Piccard inspects an instrument on his balloon (Image: Bundesarchiv, Bild 102-10382 / CC-BY-SA 3.0)

We think of human flight as a relatively modern affair, with a few claims to the first airplane all around the turn of the last century. But people flew much earlier than that by using hot air balloons as well as gas-filled ones. While the Montgolfier brothers get most of the credit for hot air ballooning in 1783, there are some reports that a Brazilian priest may have lifted himself with a balloon as early as 1709.

Regardless, we’ve had balloons a good century earlier than winged flight, if not longer. While the device is deceptively simple, it is possible to get a balloon to very high altitudes without a lot of specialized technology. Airplanes at high altitudes need a way to get enough oxygen to fuel their engines, or they have to rely on rockets. Either way, there are plenty of design and operational challenges.

Balloons, of course, can simply rise to the occasion. Auguste Piccard and an assistant took a gas-filled balloon to 15,781 meters in 1931. Their gondola was pressurized, and they were the first humans to see the curvature of the Earth and the dark sky above. That record wouldn’t stand for long, though.


The Soviet Union was keenly interested in Piccard’s flight, and the Soviet Air Force set about to build a research vessel, CCCP-1 (in English, USSR-1), that flew in 1933. The envelope was a large amount of thin fabric impregnated with latex and filled with hydrogen. The air-tight gondola presented several challenges in design. Most of the science experiments were outside, of course, and in 1933, you didn’t have an Arduino and RC servos to control things.

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Hackaday Podcast 216: FETs, Fax, And Electrochemical Fab

In this week’s podcast, non-brothers Elliot Williams and Al Williams talk about our favorite hacks of the week. Elliot’s got analog on the brain, courtesy of the ongoing Op Amp Contest, and Al is all about the retrocomputers, from a thrift-store treasure to an old, but still incredibly serviceable, voice synthesizer. Both agree that they love clever uses of mechanical parts and that nobody should fear the FET.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download your own personal copy!

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