Eggs are perhaps the most beloved staple of breakfast. However, they come with a flaw, they are incredibly messy to work with. Cracking in particular leaves egg on one’s hands and countertop, requiring frequent hand washing. This fundamental flaw of eggs inspired [Stuff Made Here] to fix it with an over-engineered egg cracking robot.
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.
Sometimes a kid wakes up on Christmas morning and runs downstairs, only hoping to see one thing: a shiny new wind tunnel. This past December, that’s exactly what [SparksAndCode]’s son found under beside the tree, complete with a bag of scarves, ping-pong balls, and other fun things to launch through it (in the name of physics, of course).
The real story here starts about a week before Christmas, when [SparksAndCode]’s son was enthralled by a similar device at a science museum. At his wife’s suggestion, [SparksAndCode] got to work designing a and building a wind tunnel with hardware-store parts, his deadline looming ahead. The basic structure of the tunnel is three rods which support plywood collars. The walls are formed by plastic sheets rolled inside the collars to make a tube. Underneath, a Harbor Freight fan supplies a nice, steady stream of air for endless entertainment.
After finding a few bugs during his son’s initial beta testing on Christmas morning, [SparksAndCode] brought the wind tunnel back into the shop for a few tweaks and upgrades, including a mesh cover on the air intake to stop things from getting sucked into the fan. The final result was a very functional (and fun!) column of air. Looking for even more function (but not necessarily less fun)? We’ve got you covered too with this home-built research wind tunnel from a few years back.
Continue reading “Homemade Toy Wind Tunnel Blows (Really Well)”
Strength. Rigidity. Dependability. The ability to bear weight without buckling. These are all things that we look for when we build a mechanical structure. And in today’s Retrotechtacular we take a closer look at the answer to a question: “What’s in A Shape?”
As it turns out, quite a lot. In a wonderful film by the prolific Jam Handy Organization in the 1940’s, we take a scientific look at how shape affects the load bearing capacity of a beam. A single sided piece of metal, angle iron, C-channel, and boxed tubing all made of the same thickness metal are compared to see not just just how much load they can take, but also how they fail.
The concepts are then given practical application in things that we still deal with on a daily basis: Bridges, cars, aircraft, and buildings. Aircraft spars, bridge beams, car frames, and building girders all benefit from the engineering discussed in this time capsule of film.
None of the concepts in this video are suddenly out of date, because while our understanding of engineering has certainly progressed since this film was made, these basic concepts remain the same. As such, they will apply to any structural or mechanical devices that we make, be it 3d printed, CNC routed, welded, glued, vacuum formed, zip tied, duct taped, bailing wired, or hot glued.
Keep your eyes open for a wonderful sights and sounds of a rare Boeing 314 Clipper landing on water and a 1920’s Buffalo Springfield Steam Roller demonstrating how wonderful the film’s sponsor, Chevrolet, makes their automobile frames.
Continue reading “Retrotechtacular: Understanding The Strength Of Structural Shapes”
Tis The Season, for those who are so inclined, to loft themselves to the top of a steep snow-covered hill and then go downhill, really fast. And if something gets in their way, turn. Whether they be on skis, a snowboard, or some other means, getting down usually involves using gravity. Getting up, on the other hand, usually involves a ski lift. And in the video by [kalsan15] after the break, we learn how technology has stepped in to make even the most inaccessible slopes just a lift ride away.
In its most simple form, a ski lift is two pulleys connected by a steel cable. The pulley at the bottom of the hill is powered, and the pulley at the top of the hill serves as an idler. Attached to the steel cable are some means for a person to either sit down or grab a handle and be hoisted to the top of the hill.
Such a simple arrangement works fine if the geography allows for it, but what if there are turns, or there need to be multiple idlers to keep the wire taut but also close to the ground? Again, the most basic ski lifts have limitations. If the cable turns left around the idler, then the attachment for the handle or chair has to be on the right, making a right turn around the idler an impossibility.
How then can this problem be solved? We won’t spoil the outcome, but we recommend checking out [kalsan15]’s video for an excellent description of the problem and the solution that’ll leave you wondering “Why didn’t I think of that!?”
If you don’t find this hacky enough, then take a moment to learn how you too can not just make a gas-powered ski lift for your cabin in the woods, but then ride your slope down on your DIY Ski Bike!
Ask any electronics hobbyist or professional what the simplest building blocks of electronic circuits are, and they’ll undoubtedly say resistors, capacitors, and inductors. Ask a mechanically-inclined person the same question about their field and the answer will probably be less straightforward. Springs would make the list for sure, but then… hmm. Maybe gears? 80/20 aluminum extrusions?
As it turns out, there are a handful of fundamental building blocks in the mechanisms world, and they’re functionally very similar, and mathematically identical, to the Big Three found in electrical engineering.
Before we look at the components themselves, let’s step back a moment and think about voltage and current. Voltage is a potential difference between two points in a circuit, sometimes called electromotive force (EMF). It turns out that EMF is an apt term for it, because it is roughly analogous to, well, force. Voltage describes how “hard” electrons are being “pushed” in a circuit. In much the same vein, current describes the rate of electric charge flow. Continue reading “Building Blocks: Relating Mechanical Elements To Electronic Components”
We have to admire a YouTube channel with the name [Less Boring Lectures]. After all, he isn’t promising they won’t be boring, just less boring. Actually though, we found quite a few of the videos pretty interesting and not boring at all. The channel features videos about mechanical engineering and related subjects like statics and math. While your typical electronics project doesn’t always need that kind of knowledge, some of them do and the mental exercise is good for you regardless. A case in point: spend seven minutes and learn about 2D and 3D vectors in two short videos (see below). Or spend 11 minutes and do the whole vector video in one gulp.
These reminded us of Kahn Academy videos, although the topics are pretty hardcore. For example, if you want to know about axial loading, shear strain, or free body diagrams, this is a good place to look.
