Cortex 2 is One Serious 3D Printed Experimental Rocket

Rocketry is wild, and [Foaly] is sharing build and design details of the Cortex 2 mini rocket which is entirely 3D printed. Don’t let that fool you into thinking it is in any way a gimmick; the Cortex 2 is a serious piece of engineering with some fascinating development.

Cortex 1 was launched as part of C’Space, an event allowing students to launch experimental rockets. Stuffed with sensors and entirely 3D printed, Cortex 1 flew well, but the parachute failed to deploy mainly due to an imperfectly bonded assembly. The hatch was recovered, but the rocket was lost. Lessons were learned, and Cortex 2 was drafted up before the end of the event.

Some of the changes included tweaking the shape and reducing weight, and the refinements also led to reducing the number of fins from four to three. The fins for Cortex 2 are also reinforced with carbon fiber inserts and are bolted on to the main body.

Here’s an interesting details: apparently keeping the original fins would result in a rocket that was “overstable”. We didn’t really realize that was a thing. The results of overstabilizing are similar to a PID loop where gain is too high, and overcorrection results in oscillations instead of a nice stable trajectory.

Cortex 2 uses a different rocket motor from its predecessor, which led to another interesting design issue. The new motor is similar to hobby solid rocket motors where a small explosive charge at the top of the motor blows some time after the fuel is gone. This charge is meant to eject a parachute, but the Cortex 2 is not designed to use this method, and so the gasses must be vented. [Foaly] was understandably not enthusiastic about venting hot gasses through the mostly-PLA rocket body. Instead, a cylindrical cartridge was designed that both encases the motor and redirects any gasses from the explosive charge out the rear of the rocket. That cartridge was SLA printed out of what looks to us like Formlabs’ High Tempurature Resin.

Finally, to address the reasons Cortex 1 crashed, the hatch and parachute were redesigned for better reliability. A servo takes care of activating the system, and a couple of reverse-polarity magnets assist in ensuring the hatch blows clear. There’s even a small servo that takes care of retracting the launch guide.

The rocket is only half built so far, but looks absolutely fantastic and we can’t wait to see more. It’s clear [Foaly] has a lot of experience and knowledge. After all, [Foaly] did convert a Makerbot printer into a CNC circuitboard engraver.

The Carbon Fiber Construction Of Large Propellers

Props for your little RC airplane or drone are effectively consumables. They’re made of plastic, they’re cheap, and you’re going to break a lot of them. When you start swinging something larger than 12 inches or so, things start getting expensive. If you’re building gigantic octocopters or big RC planes, those props start adding up. You might not think you can build your own gigantic carbon fiber propellers, but [Tech Ingredients] is here to prove you wrong with an incredible video demonstration of the construction of large propellers

The key ideas behind the build are laid out in a video demonstration for building a single prop. The base begins with a CNC wire cut foam air foil. This foam airfoil is first modified for the attachment point by cutting a plug out of the root of the airfoil which is filled with epoxy.

With the skeleton of the airfoil complete, the build then moves on to laminating the foam core with carbon fiber. The epoxy itself is West Systems Pro-Set laminating epoxy, although we suspect the ubiquitous West Systems epoxy used for all those live-edge ‘river’ coffee tables will also work as well. This epoxy is spread out on a table, the carbon fiber laid over it, and a second layer of carbon fiber (check ‘yo biases!) laid over that. This is wrapped around the foam core, then cured with an electric heating pad.

Of course, this is only a demonstration of making a single blade for a prop. The next trick is turning that single blade into a propeller. This is done with a cleverly machined hub, attached through that epoxy plug placed in the foam core. The results are just as good as any large prop you could buy, and this has the added benefit of being something you made, not bought.

This is really a master class in composite construction, and well worth an hour’s of YouTube viewing. You can check out the intro video below.

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Industrial 3D Printing Uses Layers Like We’ve Never Seen Before

We’ve seen FDM printers lay down layers by extruding plastic in a line. We’ve seen printers use sintering and lithography to melt or cure one layer at a time before more print medium moves into place for the next layer. What we’ve never seen before is a printer like this that builds parts from distinct layers of substrate.

At the International Manufacturing Technology Show last week I spoke with Eric Povitz of Impossible Objects. The company is using a “sheet lamination process” that first prints each layer on carbon fiber or fiberglass, then uses a hydraulic press and an oven to bake the part into existence before bead-blasting the excess substrate away. Check out my interview with Eric and join me below for more pictures and details.

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3D-Printed Punch and Die Stand up to Steel

When you think of machine tooling, what comes to mind might be an endmill made of tungsten carbide or a punch and die made of high-speed steel. But surely there’s no room in the machine tool world for 3D-printed plastic tools, especially for the demanding needs of punching parts from sheet metal.

As it turns out, it is possible to make a 3D-printed punch and die set that will stand up to repeated use in a press brake. [Phil Vickery] decided to push the tooling envelope to test this, and came away pleasantly surprised by the results. In fairness, the die he used ended up being more of a composite between the carbon-fiber nylon filament and some embedded metal to reinforce stress points in the die block. It looks like the punch is just plastic, though, and both were printed on a Markforged Mark 2, a printer specifically designed for high-strength parts. The punch and die set were strong enough to form 14-gauge sheet steel in a press brake, which is pretty impressive. The tool wasn’t used to cut the metal; the blanks were precut with a laser before heading to the press. But still, having any 3D-printed tool stand up to metal opens up possibilities for rapid prototyping and short production runs.

No matter what material you make your tooling out of, there’s a lot to know about bending metal. Check out the basics in our guide to the art and science of bending metal.

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Vacuum Molding with Kitchen Materials

Vacuum pumps are powerful tools because the atmospheric pressure on our planet’s surface is strong. That pressure is enough to crush evacuated vessels with impressive implosive force. At less extreme pressure differences, [hopsenrobsen] shows us how to cleverly use kitchen materials for vacuum molding fiberglass parts in a video can be seen after the break. The same technique will also work for carbon fiber molding.

We’ve seen these techniques used with commercially available vacuum bags and a wet/dry vac but in the video, we see how to make an ordinary trash bag into a container capable of forming a professional looking longboard battery cover. If the garbage bag isn’t enough of a hack, a ball of steel wool is used to keep the bag from interfering with the air hose. Some of us keep these common kitchen materials in the same cabinet so gathering them should ’t be a problem.

Epoxy should be mixed according to the directions and even though it wasn’t shown in the video, some epoxies necessitate a respirator. If you’re not sure, wear one. Lungs are important.

Fiberglass parts are not just functional, they can be beautiful. If plastic is your jam, vacuums form those parts as well. If you came simply for vacuums, how about MATLAB on a Roomba?

Thank you [Jim] who gave us this tip in the comments section about an electric longboard.

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Pi Handheld With a Mindblowing Enclosure

The Raspberry Pi is possibly the world’s most popular emulation platform these days. While it was never intended to serve this purpose, the fact remains that a small, compact computer with flexible I/O is ideally suited to it. We’ve featured a multitude of builds over the years using a Pi in a mobile form factor to take games on the go. [Michael]’s build, however, offers a lot more than a few Nintendo ROMs and some buttons from eBay. It’s a tour de force in enclosure design.

The build starts with the electronics. In 2017 it’s no longer necessary to cobble together five different accessory boards to handle the controls, battery charging, and display. Boards like Kite’s Super All In One exist, handling everything necessary for a handheld game console. With this as a starting point, he then set out to recreate Nintendo’s classic Game Boy, with a few tweaks to form and function.

It’s a textbook example of smart planning, design, and execution. We are taken through the process of creating the initial CAD drawings, then combining 3D printed parts with wood and carbon fibre for a look that is more akin to a high-end piece of hi-fi gear than anything related to gaming. The attention to detail is superb and the write-up makes it look easy, while [Michael] shares tips on how to safely cut carbon fibre to make your own buttons.

The final results are stunning, and it’s a great example of why a fine piece of wood is always a classy way to go for an enclosure. For another great example, try this walnut keyboard, or check out the roots of the Raspberry Pi Game Boy movement.

Delivery Drone Aims To Make Package Handoffs Safer Than Ever

Picture this: you’re at home and you hear a rapping on your door. At last!– your parcel has arrived. You open the door, snatch a drone out of the air, fold it up, remove your package, unfold it and set it down only for it to take off on its merry way. Hand-delivery courier drones might be just over the horizon.

Designed in the [Laboratory of Intelligent Systems] at Switzerland’s École Polytechnique Fédérale de Lausanne and funded by [NCCR Robotics], this delivery drone comes equipped with its own collapsible carbon fibre shield — it fold up small enough to fit in a backpack — and is able to carry packages such as letters, small parcels, and first aid supplies up to 500 g and to 2 km away!

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