You Can 3D Print A Working Reciprocating Steam Engine

December 22, 2021 by Lewin Day 12 Comments

3D prints aren’t typically known for their heat resistance. However, [Integza] noted that using the right techniques, it was possible to 3D print parts that could handle steam heat without failing. Thus, the natural progression from there was to build a piston-type steam engine.

The sliding valve alternately feeds steam to each side of the piston.

Resin prints are key here, as the melting point of such parts is much higher than that of those turned out by typical FDM printers. Try this same build using PLA for the hot parts, and you’ll quickly end up with a pile of molten goo.

To make such an engine work, valves are required to allow steam to flow into alternating sides of the piston to let it reciprocate continuously. A simple slide valve is used, allowing steam to flow to one side of the piston and the other alternately, as driven by an arm coming off the flywheel attached to the engine’s output shaft.

Tested on compressed air and steam, the engine ran continuously, chugging away enthusiastically. However, steam performance was compromised by the low pressure output of just 1.5 bar from [Integza]’s pressure cooker. Similarly, the cooker’s steam capacity was low, so the engine ran for just 15 seconds.

However, it suggests that with a better supply of steam, the printed steamer could indeed run for some time. If you’re not into the wetter engines out there, though, consider extruding a Stirling engine instead. Video after the break.

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Electric “Radial” RC Aircraft Motor

September 19, 2021 by Danie Conradie 23 Comments

For a long time radial aircraft engines, with their distinctive cylinder housings arranged in a circle, were a common sight on aircraft. As an experiment, [KendinYap], wanted to see if he could combine 3 small DC motors into a usable RC aircraft motor, effectively creating an electric radial engine.

The assembly consists of three “180” type brushed DC motors, mounted radially in a 3D printed casing. A 3D printed conical gear is attached to each motor shaft, which drives a single output gear and shaft mounted in the center with two bearings. The gear ratio is 3:1. A variety of propellers can be mounted using 3D printed adaptors. As a baseline, [KendinYap] tested a single motor on a scale with a 4.25-inch propeller on a scale, which produced 170 g of thrust at 21500 RPM. Once integrated into the engine housing, the three motors produced 490 g of thrust at 5700 RPM, with a larger propeller. Three independent motors and propellers should theoretically provide 510 g of thrust, so there are some mechanical losses when combining 3 of them in a single assembly. However, it should still be capable of powering a small RC plane. It’s also not impossible that a different propeller could yield better results.

While there is no doubt that it’s no match for a brushless RC motor, testing random ideas just to see if it’s possible is usually fun and an excellent learning experience. We’ve seen some crazy flyable RC power plants, including a cordless drill, a squirrel-cage blower, and a leaf blower.

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Japanese Rocket Engine Explodes: Continuously And On Purpose

September 2, 2021 by Lewin Day 62 Comments

Liquid-fuelled rocket engine design has largely followed a simple template since the development of the German V-2 rocket in the middle of World War 2. Propellant and oxidizer are mixed in a combustion chamber, creating a mixture of hot gases at high pressure that very much wish to leave out the back of the rocket, generating thrust.

However, the Japan Aerospace Exploration Agency (JAXA) has recently completed a successful test of a different type of rocket, known as a rotating detonation engine. The engine relies on an entirely different method of combustion, with the aim to produce more thrust from less fuel. We’ll dive into how it works, and how the Japanese test bodes for the future of this technology.

Deflagration vs. Detonation

Humans love combusting fuels in order to do useful work. Thus far in our history, whether we look at steam engines, gasoline engines, or even rocket engines, all these technologies have had one thing in common: they all rely on fuel that burns in a deflagration. It’s the easily controlled manner of slow combustion that we’re all familiar with since we started sitting around campfires. Continue reading “Japanese Rocket Engine Explodes: Continuously And On Purpose” →

See-Through Carburetor Gives A Clear Demonstration

July 6, 2021 by Danie Conradie 19 Comments

Carburetors have been largely phased out on most automobiles, but for a century they were the standard, and still are on many smaller engines. Armed with a high-speed camera and with the help of his father, [Smarter Every Day] investigates these devices by experimenting with a DIY see-through carburetor connected to a real engine.

The purpose of a carburetor is to mix gasoline and oxygen to the correct ratio for combustion inside the engine. Gasoline flow from the tank to the bowl, from where gets sucked into the venturi. The choke valve adjusts the amount of air entering the carb, while the throttle controls the amount of air-fuel mixture entering the engine. It appears that the carburetor was made from a resin 3D printed body and manifold, with an acrylic cover and PLA throttle and choke valves. It was attached to a single-cylinder engine.

The high-speed footage is incredible, and clearly shows the operation of the carburetor and makes it incredibly easy to understand. If you’re interested, he also uploaded a second video with almost 80 minutes of detailed footage.

[Smarter Every Day]’s infectious curiosity has led to numerous fascinating projects, including a supersonic baseball canon and the backward bicycle.

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Can The Solenoid Engine Power A Car?

June 26, 2021 by Bryan Cockfield 12 Comments

[Emiel] aka [The Practical Engineer] makes all kinds of fun projects in his fully-featured shop, and one of his tangents has been building a series of solenoid engines. These engines mimic the function of an internal combustion engine, with each solenoid acting as a piston. The only problem with [Emiel]’s concept engines, though, was that he never actually put them into a vehicle to prove their effectiveness. This build finally proves that they can work at powering a vehicle.

The project starts with a new engine. [Emiel] chose a V4 design using four solenoids and an Arduino-based controller. After some trouble getting it to operate properly, he scavenged a small circuit board he built in his V8 solenoid engine to help with timing. With that installed, the solenoids click away and spin the crankshaft at a single constant speed. The vehicle itself was mostly 3D printed, with two aluminum tubes as support structures to mount the engine. Even the wheels were 3D printed with a special rubber coating applied to them. With a small drive train assembled, it’s off to the races for this tiny prototype.

While the small car doesn’t have steering and only goes at a constant speed, the proof of concept that these tiny electric engines actually work is a welcomed addition to [Emiel]’s collection of videos on these curious engines. Of course they’re not as efficient as driving the wheels directly with an electric motor, but we all know there’s no fun in that. If you haven’t seen his most intricate build, the V8 is certainly worth checking out, and also shows off the timing circuitry he repurposed for this car.

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Differential Drive Doesn’t Quite Work As Expected

June 6, 2021 by Bryan Cockfield 10 Comments

Placing two motors together in a shared drive is a simple enough task. By using something like a chain or a belt to couple them, or even placing them on the same shaft, the torque can be effectively doubled without too much hassle. But finding a way to keep the torque the same while adding the speeds of the motors, rather than the torques, is a little bit more complicated. [Levi Janssen] takes us through his prototype gearbox that attempts to do just that, although not everything works exactly as he predicts.

The prototype is based on the same principles as a differential, but reverses the direction of power flow. In something like a car, a single input from a driveshaft is sent to two output shafts that can vary in speed. In this differential drive, two input shafts at varying speeds drive a single output shaft that has a speed that is the sum of the two input speeds. Not only would this allow for higher output speeds than either of the two motors but in theory it could allow for arbitrarily fine speed control by spinning the two motors in opposite directions.

The first design uses two BLDC motors coupled to their own cycloidal drives. Each motor is placed in a housing which can rotate, and the housings are coupled to each other with a belt. This allows the secondary motor to spin the housing of the primary motor without impacting the actual speed that the primary motor is spinning. It’s all a lot to take in, but watching the video once (or twice) definitely helps to wrap one’s mind around it.

The tests of the drive didn’t go quite as planned when [Levi] got around to measuring the stall torque. It turns out that torque can’t be summed in the way he was expecting, although the drive is still able to increase the speed higher than either of the two motors. It still has some limited uses though as he notes in the video, but didn’t meet all of his expectations. It’s still an interesting build and great proof-of-concept otherwise though, and if you’re not clear on some of the design choices he made there are some other builds out there that take deep dives into cycloidal gearing or even a teardown of a standard automotive differential.

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Tiny Gasoline Engine Fitted With A Custom Billet Waterpump

May 31, 2021 by Lewin Day 31 Comments

We don’t typically use gasoline engines smaller than 50 cc or so on a regular basis. Below that size, electric motors are typically less messy and more capable of doing the job. That doesn’t mean they aren’t cute, however. [JohnnyQ90] is a fan of tiny internal combustion engines, and decided to whip up a little water pump for one of his so it could do something useful besides make noise.

The pump is built out of billet aluminium, showing off [JohnnyQ90]’s machining skills. The two pieces that make up the main body and cover plate of the pump are impressive enough, but the real party piece is the tiny delicate impeller which actually does the majority of the work. The delicate curves of the pump blades are carefully carved out and look exquisite when finished.

The pump’s performance is adequate, and the noise of the tiny gasoline engine makes quite a racket, but it’s a great display of machining skill. If so desired, the pump could also do a great job for a small liquid delivery system if hooked up to a quiet electric motor, too. The aluminium design has the benefit of being relatively leak free when assembled properly, something a lot of 3D printed designs struggle to accomplish.

We’ve seen [JohnnyQ90]’s micro engine experiments before, too — like this small generator build. Video after the break.

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