Diaphragm Air Engine

December 2, 2020 by Danie Conradie 31 Comments

One of the tricky parts of engineering in the physical world is making machines work with the available resources and manufacturing technologies. [Tom Stanton] has designed and made a couple of air-powered 3D printed engines but always struggled with the problem of air leaking past the 3D-printed pistons. Instead of trying to make an air-tight piston, he added a rubber membrane and a clever valve system to create a diaphragm air engine.

A round rubber diaphragm with a hole in the center creates a seal with the piston at the top of its stroke. A brass sleeve and pin protrude through the diaphragm, and the sleeve seals create a plug with an o-ring, while the pin pushes open a ball which acts as the inlet valve to pressurize an intermediate chamber. As the piston retracts, the ball closes the inlet valve, the outlet valve of the intermediate chamber is opened, forcing the diaphragm to push against the piston. The seal between the piston and diaphragm holds until the piston reaches its bottom position, where the pressurized air is vented past the piston and out through the gearbox. For full details see the video after the break.

It took a few iterations to get the engine to run. The volume of the intermediate chamber had to increase and [Tom] had to try a few different combinations of the sleeve and pin lengths to get the inlet timing right. Since he wanted to use the motor on a plane, he compared the thrust of the latest design with that of the previous version. The latest design improved efficiency by 366%. We look forward to seeing it fly! Continue reading “Diaphragm Air Engine” →

Gas Powered Blender Packs Real Grunt

October 16, 2020 by Lewin Day 17 Comments

Whether you’re into fruit smoothies or icy blended cocktails, a blender comes in handy when preparing these beverages in the kitchen. But, if a small electric motor can do the job well, a noisy combustion engine can certainly do it louder. This is demonstrated ably by this project from [JT Makes It].

The build is a steel-framed contraption, mounting a small gas engine of the type you’d typically find in a weed trimmer or other garden tool. It’s attached to a shaft allowing it to spin a blender blade at up to 41,000 rpm when unloaded. A stout metal container is mounted on top, along with a plexiglass lid to ensure the contents of the bowl don’t escape when the blender is in action.

It’s a fun build, and one that has no trouble turning a bucket of apples into mush in under 60 seconds. More realistically, [JT] is able to whip up several litres of blended cocktail without major effort, which would be great for parties. Though, we do imagine the burning oil and gas fumes does somewhat spoil the taste sensation. We’ve seen similar hacks before, like this nitro-fuelled pencil sharpener. Video after the break.

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Making A Modern Version Of A Steam Engine From Antiquity

October 6, 2020 by Dan Maloney 28 Comments

Imagine traveling back in time about 2,200 years, to when nothing moves faster than the speed at which muscle or wind can move it. Think about how mind-shattering it would have been to see something like Hero’s Engine, the first known example of a steam turbine. To see a sphere whizzing about trailing plumes of steam while flames licked around it would likely have been a nearly mystical experience.

Of course we can’t go back in time like that, but seeing a modern replica of Hero’s Engine built and tested probably isn’t too far from such an experience. The engine, also known as an aeolopile, was made by the crew over at [Make It Extreme], whose metalworking videos are always a treat to watch. The rotor of the engine, which is fabricated from a pair of hemispherical bowls welded together, is supported by pipes penetrating the lid of a large kettle. [Make It Extreme] took great pains to make the engine safe, with relief valves and a pressure gauge that the original couldn’t have included. The aeolopile has a great look and bears a strong resemblance to descriptions of the device that may or may not have actually been invented by Greek mathemetician [Heron of Alexandria], and as the video below shows, when it spins up it puts on a great show.

One can’t help but wonder how something like this was invented without someone — anyone — taking the next logical step. That it was treated only as a curiosity and didn’t kick off the industrial revolution two millennia early boggles the mind. And while we’ve seen far, far simpler versions of Hero’s Engine before, this one really takes the cake on metalworking prowess.

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1/3 Scale Hybrid RC Car With A Scratch-Built 125cc V10 Engine

September 20, 2020 by Danie Conradie 20 Comments

Scale model engines are fascinating pieces of engineering, and RC cars are always awesome to play with, no matter your age. [Keith57000] has gone over the top on both, creating a seriously impressive hybrid RC car built around a custom 125 cc V10 engine.

[Keith57000] started building the V10 engine back in 2013, after completing a 1/4 scale V8. The build is documented in a forum thread with lots of pictures of his beautiful craftsmanship. Most of the mechanical components were machined on a manual lathe and milling machine. No CNC, just lots of drawings and measurements, clever use of dividing heads, and careful dial reading. The engine also features electronic fuel injection with a MegaSquirt controller.

The rest of the car is just as impressive as the power plant. The chassis is bent tube, with machined brackets and carbon fiber suspension components. Two electric skateboard motors are added to give it a bit more power. The three speed gearbox is also custom, built with gears scavenged from a pit bike and angle grinder. It uses two small pneumatic pistons to do the shifting, with a clever servo mechanism that mechanically switches the solenoid valves. Check out all fourteen build videos on his channel for more details.

An amateur project of this complexity is never without speed bumps, which [Keith57000] details in the videos and build thread. It has taken seven years so far, but it is without a doubt the most impressive RC car we’ve seen. His skill with manual machine tools is something we rarely get to see in the age of CNC. We’re looking forward to the finished product, hopefully screaming around a track with a FPV cockpit.

Print-in-Place Engine Aims To Be The Next Benchy

August 27, 2020 by Dan Maloney 19 Comments

While there are many in the 3D-printing community who loudly and proudly proclaim never to have stooped to printing a 3DBenchy, there are far more who have turned a new printer loose on the venerable test model, just to see what it can do. But Benchy is getting a little long in the tooth, and with 3D-printers getting better and better, perhaps a better benchmarking model is in order.

Knocking Benchy off its perch is the idea behind this print-in-place engine benchmark, at least according to [SunShine]. And we have to say that he’s come up with an impressive model. It’s a cutaway of a three-cylinder reciprocating engine, complete with crankshaft, connecting rods, pistons, and engine block. It’s designed to print all in one go, with only a little cleanup needed after printing before the model is ready to go. The print-in-place aspect seems to be the main test of a printer — if you can get this engine to actually spin, you’re probably set up pretty well. [SunShine] shares a few tips to get your printer dialed in, and shows a few examples of what can happen when things go wrong. In addition to the complexities of the print-in-place mechanism, the model has a few Easter eggs to really challenge your printer, like the tiny oil channel running the length of the crankshaft.

Whether this model supplants Benchy is up for debate, but even if it doesn’t, it’s still a cool design that would be fun to play with. Either way, as [SunShine] points out, you’ll need a really flat bed to print this one; luckily, he recently came up with a compliant mechanism dial indicator to help with that job.

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80 Years From Invention, China Is Struggling With Jet Engines

July 28, 2020 by Lewin Day 128 Comments

The jet engine has a long and storied history. Its development occurred spontaneously amongst several unrelated groups in the early 20th Century. Frank Whittle submitted a UK patent on a design in 1930, while Hans von Ohain begun exploring the field in Germany in 1935. Leading on from Ohain’s work, the first flight of a jet-powered aircraft was in August 27, 1939. By the end of World War II, a smattering of military jet aircraft had entered service, and the propeller was on the way out as far as high performance aviation is concerned.

With the invention of the jet engine so far in the past, one could be forgiven for thinking that the technology has long been mastered around the world. However, recent reports show that’s not the case. China is a great example, facing issues with the development of jet engines for their indigenous military aircraft.

Closely Guarded Secrets

China’s development of ballpoint pen tips was a national news story in 2017. Source: Xinhua

In the age of the Internet and open source, technology moves swiftly around the world. In the consumer space, companies are eager to sell their product to as many customers as possible, shipping their latest wares worldwide lest their competitors do so first. In the case of products more reliant on infrastructure, we see a slower roll out. Hydrogen-powered cars are only available in select regions, while services like media streaming can take time to solve legal issues around rights to exhibit material in different countries. In these cases, we often see a lag of 5-10 years at most, assuming the technology survives to maturity.

In most cases, if there’s a market for a technology, there’ll be someone standing in line to sell it. However, some can prove more tricky than others. The ballpoint pen is one example of a technology that most of us would consider quaint to the point of mediocrity. However, despite producing over 80% of the world’s ballpoint pens, China was unable to produce the entire pen domestically. Chinese manufactured ballpoint tips performed poorly, with scratchy writing as the result. This attracted the notice of government officials, which resulted in a push to improve the indigenous ballpoint technology. In 2017, they succeeded, producing high-quality ballpoint pens for the first time.

The secrets to creating just the right steel, and manipulating it into a smooth rolling ball just right for writing, were complex and manifold. The Japanese, German, and Swiss companies that supplied China with ballpoint tips made a healthy profit from the trade. Sharing the inside knowledge on how it’s done would only seek to destroy their own business. Thus, China had to go it alone, taking 5 years to solve the problem.

There was little drive for pen manufacturers to improve their product; the Chinese consumer was more focused on price than quality. Once the government made it a point of national pride, things shifted. For jet engines, however, it’s somewhat of a different story.

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How To Get Into Cars: Nat Atmo Engine Mods

May 19, 2020 by Lewin Day 54 Comments

While the car world is obsessed with everything boosted these days, many still yearn for the smooth power delivery and sonorous tone of a naturally aspirated engine. Of course, everyone still wants to go fast, so here’s how you go about getting more power out of your car without bolting on a big turbo or whining supercharger.

Intakes: This Can Get Pretty Invovled

A modified intake installed on a Honda S2000. Also referred to as “cold-air intakes”, they aim to suck in air at lower temperature which helps produce more power – hence the shield between the air filter and exhaust.

The intake is one of the first modifications made by many budding car enthusiasts. Throwing on a chromed intake pipe with a big pod filter was the mod to have back in the Fast and Furious era. Power gains can be had, though typically these are minor – on the order of 5-10 horsepower at most. It all depends on the car in question. A BMW M5 V10 was designed for high performance, with a highly advanced intake with individual throttle bodies from the factory. It’s unlikely any eBay parts are going to unlock horsepower that BMW’s engineers didn’t already find. Conversely, early Mazda Miatas are known to have a restrictive intake, largely due to the flap-type air flow meter. Replacing this with a freer-flowing setup has merit.

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