I went to SKF to learn how to design a proper bearing arrangement and share their knowledge with you all. Thank you to Roger and the team at SKF for supporting the Marble Machine :)

Download the Roller Bearing pdf here:
https://cdn.skfmediahub.skf.com/api/public/0901d196802809de/pdf_preview_medium/0901d196802809de_pdf_preview_medium.pdf#cid-121486

Download the SKF SIMPRO QUICK Simulation Software here:
https://www.skf.com/group/support/eng...

The above two tools are really powerful, hopefully they can help guide your own projects correctly.

This catalogue contains detailed information on SKF rolling bearings that are typically used in industrial applications. //

When selecting bearings for any purpose, ultimately you want to be certain of achieving the required level of equipment performance – and at the lowest possible cost. In addition to the bearing rating life, there are other key factors you must consider when putting together the bearing specifications for an application. The bearing selection process helps to evaluate these key factors.

Go to section B, page 60, to learn more about bearing selection.

INNengine of Granada, Spain had produced a opposed-piston engine that packed a pretty powerful punch in an extremely tiny package.

There's no cylinder head in this motor. Also no crankshaft, no camshaft, and no valves. That's why it's no surprise that this engine tips the scales at just 85 pounds. Somehow, it still produces 120 horsepower with just half a liter of displacement, thanks to what the company calls a single-stroke combustion cycle. //

Despite having four cylinder banks, the INNengine (depending on its configuration) actually has eight pistons. This is because the engine is an opposed-piston motor, meaning that each piston's compression stroke is performed against a second piston placed in the same cylinder bank rather than a static cylinder head. It still only has four combustion chambers, though, which means it sounds similar to a four-cylinder engine.

There are no connecting rods to be seen in this motor (at least not in a traditional sense). Instead, the pistons sit on rollers that ride against a lobed circular plate which can be adjusted to affect the engine's timing and compression ratio. As the lobe reaches its peak, the piston rushes towards top-dead-center where fuel is directly injected into the cylinder and a spark plug ignites the compressed air-fuel mixture.

https://www.thedrive.com/uploads/2023/07/14/innengine-1.gif?auto=webp&optimize=high&quality=70&width=750

The mechanical configuration also allows for better engine balance. That means typical drawbacks of an internal combustion motor (often referred to as noise, vibration, and harshness) are minimalized.

Once combustion happens, the piston is pushed back against the plate and forces the plate to rotate. This motion is synced between each half of the motor via a shared shaft—meaning, no extra timing components. Both pistons in the same cylinder bank mimic one another's movements almost exactly.

When the pistons reach the bottom of their strokes, a respective intake and exhaust port is uncovered. One piston is timed to reach bottom-dead-center slightly prior to the other, this allows the exhaust gasses to escape out of the exhaust port and create a vacuum inside of the cylinder—this technique is called scavenging. Fresh air is then pulled in via the intake port as the combustion byproduct is expelled. This effectively gives the pistons double duty, performing the work normally handled by valves in a typical combustion engine—which means that the common drawback of direct injection, carbon-laced valves, is a thing of the past. //

Now, here's the thing: this motor isn't a one-stroke engine. It has a compression stroke and exhaust stroke, making it a two-stroke cycle. INNengine acknowledges this and has said that it brands the motor as such because people would assume that a two-stroke engine would need to have oil mixed in along with fuel. Most two-strokes do. The company says that the one-stroke name was suggested by an "external ICE institution" and they found it to be "catchy," so INNengine stuck with it. //

the company seems to be instead targeting the EV market as a range extender, especially since that's the way the industry is ultimately headed.

The ancient Romans were master builders and engineers, perhaps most famously represented by the still-functional aqueducts. And those architectural marvels rely on a unique construction material: pozzolanic concrete, a spectacularly durable material that gave Roman structures their incredible strength.

Even today, one of their structures – the Pantheon, still intact and nearly 2,000 years old – holds the record for the world's largest dome of unreinforced concrete.

The properties of this concrete have generally been attributed to its ingredients: pozzolana, a mix of volcanic ash – named after the Italian city of Pozzuoli, where a significant deposit of it can be found – and lime. When mixed with water, the two materials can react to produce strong concrete.

But that, as it turns out, is not the whole story. An international team of researchers led by the Massachusetts Institute of Technology (MIT) found that not only are the materials slightly different from what we may have thought, but the techniques used to mix them were also different.

The smoking guns were small, white chunks of lime that can be found in what seems to be otherwise well-mixed concrete. The presence of these chunks had previously been attributed to poor mixing or materials, but that did not make sense to materials scientist Admir Masic of MIT. //

One of the questions in mind was the nature of the lime used. The standard understanding of pozzolanic concrete is that it uses slaked lime. First, limestone is heated at high temperatures to produce a highly reactive caustic powder called quicklime, or calcium oxide.

Mixing quicklime with water produces slaked lime, or calcium hydroxide: a slightly less reactive, less caustic paste. According to theory, it was this slaked lime that ancient Romans mixed with the pozzolana.

Based on the team's analysis, the lime clasts in their samples are not consistent with this method. Rather, Roman concrete was probably made by mixing the quicklime directly with the pozzolana and water at extremely high temperatures, by itself or in addition to slaked lime, a process the team calls "hot mixing" that results in the lime clasts.

"The benefits of hot mixing are twofold," Masic said.

"First, when the overall concrete is heated to high temperatures, it allows chemistries that are not possible if you only used slaked lime, producing high-temperature-associated compounds that would not otherwise form. Second, this increased temperature significantly reduces curing and setting times since all the reactions are accelerated, allowing for much faster construction."

And it has another benefit: The lime clasts give the concrete remarkable self-healing abilities.

When cracks form in the concrete, they preferentially travel to the lime clasts, which have a higher surface area than other particles in the matrix. When water gets into the crack, it reacts with the lime to form a solution rich in calcium that dries and hardens as calcium carbonate, gluing the crack back together and preventing it from spreading further. //

It could also explain why Roman concrete from seawalls built 2,000 years ago has survived intact for millennia despite the ocean's constant battering.

You might have noticed there’s something wrong with this bike. Or you might have not.

This bicycle is missing a very important part of its frame and it would immediately break if it actually existed and someone tried to ride it.

Let me explain everything from the beginning:
back in 2009 I began pestering friends and random strangers. I would walk up to them with a pen and a sheet of paper asking that they immediately draw me a men’s bicycle, by heart. Soon I found out that when confronted with this odd request most people have a very hard time remembering exactly how a bike is made. Some did get close, some actually nailed it perfectly, but most ended up drawing something that was pretty  far off from a regular men’s bicycle.

Little I knew this is actually a test that psychologists use to demonstrate how our brain sometimes tricks us into thinking we know something even though we don’t.
 
I collected hundreds of drawings, building up a collection that I think is very precious. There is an incredible diversity of new typologies emerging from these crowd-sourced and technically error-driven drawings. A single designer could not invent so many new bike designs in 100 lifetimes and this is why  I look at this collection in such awe.  //

In early 2016 I eventually decided it was my turn to take part in this project.

I decided my job was going to be presenting the potential and the beauty inside these sketches. I selected those that I found most interesting and genuine and diverse, then rendered them as if they were real. I became the executor of these two minute projects by people who were mainly non-designers and confirmed my suspicion: everyone, regardless his age and job, can come up with extraordinary, wild, new and at times brilliant inventions.

Basically, a PID loop can be thought of very simply as an equation that takes your current state as input and gives you what you need to do to reach a desired state as output. For example, if you had a radiator and wanted to heat a room, the PID loop would take the current temperature as input and tell you how high you needed to set the radiator on a 0-100% scale to achieve a desired temperature.

The PID loop has three components, and to tune it you need to set three weights that you multiply each parameter with. That means that it’s basically output = Pprop, + Iintgr + D*deriv, where the terms are explained below:

P - proportional: This is the weight of the difference between the current position and the desired position. What this says about the radiator is “we’re still far away, we need more heat!”, so the more P you set, the higher the radiator will be set for a given temperature difference.

D - derivative: Because P is purely based on the difference between the current and target temperatures, it doesn’t know anything about inertia. So, even though your radiator will be getting closer to the target temperature, even when it’s very close, P will be saying “more heat, we’re not there yet!”, and cause you to overshoot your target, having to then go back (possibly turning the AC on, undershooting downwards, and then back upwards, oscillating like that for a long time). D helps by saying “whoa, we’re getting there, slow down with the heat”, and reducing the amount of heat you apply proportionally to how fast you’re getting to your target temperature.

I - integral: I helps in the case where you left a window open in the room, and P is saying “okay we’re pretty close so set the radiator to 10% just for that final push”, but the room is leaking so that 10% will never get you to your target temperature. I helps by saying “Okay we’ve been trying but it’s not working, we’re still far, so we actually need a bit more heat than 10%”, by looking at the constant temperature difference you’ve been having lately, despite your best efforts. Basically, I deals with accumulated error when you think you’re getting closer but all you’re doing is fighting losses, so I allows you to close that gap.

“I have discovered the secrets of the pyramids, and have found out how the Egyptians and the ancient builders in Peru, Yucatan, and Asia, with only primitive tools, raised and set in place blocks of stone weighing many tons!” –Edward Leedskalnin

Coral Castle is an unsolved megalith whose secrets of construction can be uncovered and proved using only information found on the Internet. This article presents the proof and links the technology used to construct it to a scientist’s theory for Egyptian pyramid construction that was rejected several decades ago.

THE FIFTY-NINE-STORY CRISIS, The New Yorker, 5/29/95, pp 45-53
CITY PERILS
THE FIFTY-NINE-STORY CRISIS
THE NEW YORKER, MAY 29, 1995, pp 45-53
What's an engineer's worst nightmare? To realize that the supports he designed for a skyscraper like Citicorp Center are flawed---and hurricane season is approaching.

Last May, researchers at the U.S. Naval Research Laboratory in Washington, DC revealed that elastic response and engineered gradient materials could be combined to make extremely efficient acoustic metamaterials, according to Physics Today.

Electrical engineers should understand what power factor correction is, why engineers should correct power factor, the evolution from power factor to true power factor and various power factor correction techniques

Energy in general is defined as the capacity for doing work. Power is the rate of doing work or the rate of using energy:
P=Work/t=Energy/t , where t is time.

Although casually the terms energy and power are often used interchangeably, we see that technically they have different meanings. The SI unit of energy and work (which are numerically the same) is the joule (J). A joule is the work done by a force of one newton for a distance of one meter. This unit is usually used in physics. Energy comes in many forms, such as heat, motion, gravitational, radiated solar power, and electrical. For different types of energy other physical units are also utilized. For example, the British Thermal Unit (Btu) is often used to measure the heat energy or compare fuels. One Btu is what's needed to heat one pound of water one degree F. The SI derived unit of power is watt (W). Watt is power required to produce or consume one joule of energy per second. This unit and its multiple kilowatt are usually utilized in ratings of various electric loads and sources of electricity, such as residential generators.

In the heated jungles of Central America in the early 1900s, thousands of workers toiled in the rain and mud trying to cleave Panama in half in order to join the Pacific Ocean with the Caribbean Sea. The difficult, dirty work involved more than digging and dynamiting, though. Working on the Panama Canal in the early days was about simply surviving.

How tight is hand tight torque?

Adjective. finger tight. (of a screwed connection) tightened using the fingers, and no tools, to a torque of about 15 to 20 inlb or 1.7 to 2.3 Nm.

Transparently Obvious
mechanical gifs are Physical Models you can hold in your hand

My mechanical gifs are not animated gifs of the kind you find all over the internet. Instead they are real, physical objects that serve the same purpose. They help you understand how common and uncommon machines, mechanisms, gadgets, and devices work. You can hold them in your hand and put them through their paces as fast or as slow as you like until it all makes sense. There is no substitute for the physical intuition this sort of hands-on experience gives you.

They are are also fun, beautiful, and make great gifts. They are, in short, giftable gifs!

Each model is laser-cut from crystal clear acrylic and assembled by you using the included nuts, bolts, and tools. Online assembly videos make it easy to get everything put together and working. The models work smoothly, with the satisfying sound of precision-cut, high-quality materials.

London-based Solar Water PLC recently signed an agreement with the Saudi Arabian government as part of the country's clean future $500 billion "NEOM" project. The company is building the "first desalination plant with solar dome technology", a CNN Arabia report (translated on Solar Water PLC's website) explains. //

The plant is essentially "a steel pot buried underground, covered with a dome," making it look like a ball, Solar Water CEO David Reavley told CNN Arabia. The glass dome, a form of concentrated solar power (CSP) technology, is surrounded by "heliostat" reflectors that focus solar radiation towards inwards. Heat is transferred to seawater within the dome, which evaporates and then condenses to form freshwater. The solar dome plant does not utilize polluting fibers that are typically used in reverse osmosis desalination technologies, and Reavley claims that it is cheap and fast to build at the same time as being carbon neutral.

This memo documents the fundamental truths of networking for the Internet community. This memo does not specify a standard, except in the sense that all standards must implicitly follow the fundamental truths. //

2. The Fundamental Truths

(1) It Has To Work.

(2) No matter how hard you push and no matter what the priority, you can't increase the speed of light.

(2a) (corollary). No matter how hard you try, you can't make a baby in much less than 9 months. Trying to speed this up might make it slower, but it won't make it happen any quicker.

(3) With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead.

(4) Some things in life can never be fully appreciated nor understood unless experienced firsthand. Some things in networking can never be fully understood by someone who neither builds commercial networking equipment nor runs an operational network.

(5) It is always possible to aglutenate multiple separate problems into a single complex interdependent solution. In most cases this is a bad idea.

(6) It is easier to move a problem around (for example, by moving the problem to a different part of the overall network architecture) than it is to solve it.

(6a) (corollary). It is always possible to add another level of indirection.

(7) It is always something

(7a) (corollary). Good, Fast, Cheap: Pick any two (you can't have all three).

(8) It is more complicated than you think.

(9) For all resources, whatever it is, you need more.

(9a) (corollary) Every networking problem always takes longer to solve than it seems like it should.

(10) One size never fits all.

(11) Every old idea will be proposed again with a different name and a different presentation, regardless of whether it works.

(11a) (corollary). See rule 6a.

(12) In protocol design, perfection has been reached not when there is nothing left to add, but when there is nothing left to take away.

Now, as engineers, technical people or specialists in general, we hate to be told what to do exactly. We love it when you let us know what you want to achieve and when you need it, so we can get on with it and make it happen. If you also tell us why you need it, we might opine you actually don’t and there is a better way of doing it.

Just don’t tell us exactly how, because that is our job. In other words, tell us the desired outcome, relevant constraints, timeline, motivation and we’ll do our best.

Or at least that is how we like to feel about how we work. In fact we might disagree a lot with the what, the why and the when, and we can be super stubborn and difficult. But the idea remains — let us do our job, and we’ll deliver better results than when you micromanage us. //

On the flip side of the coin however.. many/most of us aren’t well equipped to pick up hints, interpret your stories as orders, or read between the lines to figure out your real meaning. Sorry. Something had to give when we learned 15000 pages of expert and arcane knowledge, and this was it.

And we might not even apologise — communicating indirectly about technical matters is asking for trouble. If you indicate vaguely what you want, you are likely to exactly not get it.

So on behalf of subject matter experts that are frankly somewhat wonky & geeky: please know we require slightly different handling than your other colleagues. Talking to us in hints and stories may be polite, but we might not pick up that you are sending us a serious message or asking us to do specific things. Do not put your important message between the lines.

When in doubt: be explicit. It will almost never hurt. Just leave us some room on the “how”.

‘How is it that despite 100 years of engineering advances, the same project now took five times as long? Did we just forget how to build things?’ //

Bridges, roads, and other modern infrastructure projects in the United States take exceptionally longer to complete compared to those in other nations. A new video from Kite and Key creators breaks down exactly why a combination of government regulations and bad management causes such lengthy delays in assembling the transportation and urban foundation of American cities.

The Golden Gate Bridge and Empire State building are just two examples of speedy and successful construction projects in the United States, the video begins, but now significantly smaller buildings, bridges, and other proposals are taking an abnormally long time to finish. //

“Better safety isn’t the reason that America is falling behind. After all, countries like Germany and Canada, build new infrastructure, much faster and cheaper than we do. And they do it without a body count,” the narrator explained.

In reality, it is a fatal combination of government regulation and bad management that is killing American infrastructure plans and creating decades of setbacks. The video shows how laws such as the National Environmental Policy Act were “well-intentioned” at the time of their creation yet ultimately fail to accomplish much but delaying new construction.

“Its goal was to make sure that new construction factored in environmental concerns … maybe it’s all worth it to protect the planet right? But here’s the craziest part: nothing about NEPA actually requires that. All you have to do is identify environmental issues. There’s nothing that forces you to actually do anything about them. In fact, in some cases, these regulations actually make us less green,” the narrator continued, noting examples such as in Montana, where the U.S. Forest Service delayed cutting back forests and a wildfire burned “nearly half the land” during the NEPA waiting period.

The first form calculates the pressure or friction loss along a given length of pipeline with a specified inside diameter. The second form calculates the minimum pipe size to limit pressure loss to a specified value.

Additional friction pressure losses occur due to fittings. These losses in-effect add extra additional length to the total pipeline. Use this calculator to estimate how much additional length needs to be added to the overall pipe length below in order to estimate these additional losses. Learn more about the units used on this page.