There are plenty of rocket experimenters toying with various liquid-fueled contraptions at the moment, and [Sciencish] is one of them. He grew tired of using air-pressurized fuel delivery systems in his experiments due to safety reasons, and decided to create something approximating more grown up rocket designs. The result was a 3D-printed turbopump for fuel delivery.
The design is not dissimilar from a turbocharger in a car. On one side, a turbine wheel is turned by compressed air supplied from a tank or compressor. This turbine wheel is affixed to the same axle as an impeller which draws up fuel and pumps it out, ideally into a rocket’s combustion chamber. It’s all made out of resin-printed parts, which made creating the fine geometry of the turbine and impeller a cinch.
Running on compressed air at 80 psi, the turbopump is able to deliver 1.36L of water or rubbing alcohol fuel a minute. However, unfortunately, this first pass design can only deliver 20 psi of fuel pressure, which [Sciencish] suspects will not be enough to counteract combustion chamber pressures in his rocket design. More work is required to up this figure. Paired with a nozzle and ignition source, though, and it does make for some great flames.
Overall though, the safety benefit of this turbopump comes from the fact that the fuel is kept separate from the oxidizer until it reaches the combustion chamber. This comes with far less chance of fire or explosion versus a system that stores fuel pressurized by air.
While the design isn’t yet up to scratch for rocket use, it nonetheless works, and we suspect with some improvement to tolerances and fin design that the project should move along at a quick pace.
Surfing is a fun and exciting sport but a lot of beginners can get discouraged with how little time is spent actually riding waves while learning. Not only are balance and wave selection critical skills that take time to learn, but a majority of time in the water is spent battling crashing waves to get out past the breakers. Many people have attempted to solve this problem through other means than willpower alone, and one of the latest attempts is [Andrew W] with a completely DIY surfboard with custom impeller jet drives.
The surfboard is hand-made by [Andrew W] himself using a few blocks of styrofoam glued together and then cut into a generic surfboard shape. After the rough shaping is done, he cuts out a huge hole in the back of the board for the jet drive. This drive is almost completely built by [Andrew] as well including the impeller pumps themselves which he designed and 3D printed. The pair of impellers are driven by some beefy motors and a robust speed controller that connects wirelessly to a handheld waterproof throttle to hold while surfing. Once everything was secured in the motor box the surfboard was given a final shaping and then glassed. The final touch was an emergency disconnect attached to a leash so that if he falls off the board it doesn’t speed away without him.
The build is impressive not only for [Andrew]’s shaping skills but for his dedication to a custom jet drive for the surfboard. He spent over a year refining the build and actually encourages people not to do this as he thinks it took too much time and effort, but we’re going to have to disagree with him there. Even if you want to try to build something a lot simpler, builds like these look like a lot of fun once they’re finished. The build seems flawless and while he only tested it in a lake we’re excited to see if it holds up surfing real waves in an ocean.
There are a lot of cliches about the perils of boat ownership. “The best two days of a boat owner’s life are the day they buy their boat, and the day they sell it” immediately springs to mind, for example, but there is a loophole to an otherwise bottomless pit of boat ownership: building a small robotic speedboat instead of owning the full-size version. Not only will you save loads of money and frustration, but you can also use your 3D-printed boat as a base for educational and research projects.
The autonomous speedboats have a modular hull design to make them easy to 3D print, and they use a waterjet for propulsion which improves their reliability in shallow waters and reduces the likelihood that they will get tangled on anything or injure an animal or human. The platform is specifically designed to be able to house any of a wide array of sensors to enable people to easily perform automated tasks in bodies of water such as monitoring for pollution, search-and-rescue, and various inspections. A monohull version with a single jet was prototyped first, but eventually a twin-hulled catamaran with two jets was produced which improved the stability and reliability of the platform.
All of the files needed to get started with your own autonomous (or remote-controlled) speedboat are available on the project’s page. The creators are hopeful that this platform suits a wide variety of needs and that a community is created of technology enthusiasts, engineers, and researchers working on autonomous marine robotic platforms. If you’d prefer to ditch the motor, though, we have seen a few autonomous sailboats used for research purposes as well.
Typically in the RC community, radio control boats rely on small nitro engines or electric motors to get around. Fitted with traditional propellers, they’re capable of great speed and performance. Of course, there’s more than one way to skin a cat, as [Integza] shows with his latest build.
As far as the boat side of things is concerned, it’s a basic 3D printed single hull design. The innovation comes in the drivetrain, instead. The boat uses compressed air for propulsion, stored in a battery of four soda bottles, pressurized to 6 bar. The compressed air is used to drive a Tesla turbine of [Integza]’s design, which is 3D printed on a resin printer. Rather then driving a propeller, the Tesla turbine instead turns a Lily impeller, which pulls the boat through the water rather than pushing it along. The impeller uses a nature-inspired design, hence the name, and was also 3D printed, making producing its complex geometry a cinch. The guts of a toy radio control car are then used to control the boat.
Understandably, performance is less than stellar. The limited reserves of compressed air can’t propel the boat long, and the combination of the high RPM Tesla turbine and Lily impeller don’t provide a lot of thrust. However, the boat does move under its own power, demonstrating these oddball technologies while doing so.
As [Marius Hornberger] was working in his woodshop, a thunderous bang suddenly rocked the space. A brief search revealed the blower for the dust collector had shifted several inches despite being stoutly fastened down. Turns out, the blower had blown itself up when one of the impeller fins came loose. Time to revise and build a bigger, better dust collector!
[Hornberger] is thorough in describing his process, the video series chronicles where he went astray in his original design and how he’s gone about improving on those elements. For instance, the original impeller had six fins which meant fewer points to bear the operating stresses as well as producing an occasionally uncomfortable drone. MDF wasn’t an ideal material choice here either, contributing to the failure of the part.
[Mark Rehorst] has been on the hunt for the perfect 3D printer cooling fan and his latest take is a really interesting design. He’s printed an impeller and housing, completing the fan using a hard drive motor to make it spin.
We should take a step back to see where this all began. Many 3D printers us a cooling fan right at the tip of the extruder because the faster you faster you cool the extruded filament, the fewer problems you’ll have with drooping and warping. Often this is done with a small brushless fan mounted right on the print head. But that adds mass to the moving head, contributing to problems like overshoot and oscillation, especially on larger format printers that have longer gantries. [Mark] just happens to have an enormous printer we covered back in January and that’s the machine this fan targets.
Make sure you give [Mark’s] Mother of all print cooling fansarticle a look. His plan is to move the fan off of the print head and route a flexible tube instead. He tried a couple of fans, settling on one he pulled from a CPAP machine (yes the thing you wear at night to combat sleep apnea) found in the parts bin at Milwaukee Makerspace. It works great, moving quite a bit more air than necessary. The problem is these CPAP parts aren’t necessarily easy to source.
You know what is easy to source? Old hard drives. [Mark] mentions you likely have one sitting around and if not, your friends do. We have to agree with him. Assuming you already have a 3D printer (why else do you want to print this fan?), the only rare part in this mix is the ESC to make the motor spin. Turns out we just saw a BLDC driver build that would do the trick. But in [Mark’s] case he found a rather affordable driver that suits his needs which is used in the video demo below.
[Ben Krasnow’s] water vortex machine has been an exhibit in the lobby of the San Jose City Hall for quite some time now. Unfortuantely he recently had to perform some repair work on it due to the parts inside the water chamber rusting.
This is the same water vortex that we saw about a year ago. It uses a power drill to drive an impeller at the bottom of a water column to produce the vortex. That impeller was made from painted steel and after being submerged for eight months it began rusting, which discolored the water. [Ben’s] repair process, which you can watch after the break, replaces the shaft and the impeller. He reused a plastic PC cooling fan as the new impeller. The replacement shaft is stainless steel, as is all of the mounting hardware that will be in contact with water. But for us, the most interesting part of the repair is his explanation of the shaft gasket and bearings. Two thrust bearings and two radial bearings ensure that the shaft cannot move axially, which would cause a problem with the gasket. He had intended to swap out the oil seal for an all Teflon seal but the machined acrylic wasn’t conducive to the part swap. Instead, he replaced it with the same type of gasket, but bolstered the new one with some silicone to stave off corrosion.