Tilt-Rotor Plane Needs Flight Controller Hack To Get Airborne

Part of the charm of quadcopters is the challenge that building and flying them presents. In need of complex sensors and computational power to just get off the ground and under tremendous stresses thanks to their massively powerful motors, they often seem only barely controlled in flight. Despite these challenges, quadcopter flight has been reduced to practice in many ways, leaving hobbyists in search of another challenge.

[Tom Stanton] is scratching his creative itch with this radio-controlled tilt-rotor airplane that presents some unique problems and opportunities. Tilt-rotor planes are, as the name implies, able to swivel their propellors and transition them from providing forward thrust to providing verticle lift. With the rotors providing lift, the aircraft is able to hover and perform vertical take-off and landing (VTOL); switched to thrust mode, wings provide the lift for horizontal flight.

[Tom]’s realization of this design seems simple – a spar running through the wing holding BLDC motors and props is swiveled through 90° by a servo to transition the aircraft. Standard control surfaces on the wings and tail take care of horizontal flight. Actually getting an off-the-shelf flight controller to deal with the transitions was tricky. [Tom] ended up adding an Arduino to intercept the PWM signals the flight controller normally sends directly to the servos and speed controls to provide the coordination needed for a smooth transition. Full details in the video below, and some test flights which show that an RC VTOL is anything but a beginner’s plane.

[Tom] is proving himself to be quite the Renaissance man these days. Between air-powered piston engines, over-balance trebuchets, and popping the perfect wheelie, he seems to have covered all the bases and done his best to keep our tip line stocked.

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Wind Turbine Pushes Limits Of Desktop 3D Printing

There was a time, not so long ago, when hype for desktop 3D printing as so high that it seemed you could print anything. Just imagine it, and your handy dandy magical 3D printer could manifest it into reality. But now that more people have had first hand experience with the technology, the bubble has burst. Reality has sobered us up a bit, and today we’ve got a much better idea of what can and cannot be printed on a traditional desktop 3D printer.

But that doesn’t mean we aren’t surprised from time to time. As a perfect example, take a look at this almost entirely 3D printed wind turbine designed and built by [Nikola Petrov]. Outside of the electronics, the pole it’s mounted to, and some assorted bits and bobs, he produced all the parts on his own large-format TEVO Black Widow printer. He mentions there are a few things he would do differently if he was to build another one, but it’s hard to find much to complain about with such a gorgeous build.

To be sure, this one isn’t for the 3D printing novice. First of all, you’ll need a printer with a bed that’s at least 370 mm wide just to print the blades. [Nikola] also recommends printing the parts in ABS and coating them with acetone to smooth and harden the outside surfaces. We’d be surprised if you could print such large objects in ABS without a heated enclosure as well, so plan on adding that to your shopping list.

On the flip side though, the electronics are about as simple as they come. The blades are spinning a standard NEMA 17 stepper motor (through a 1:5 gearbox) to produce AC power. This is then fed into two W02M rectifiers and a beefy capacitor, which gives him DC with a minimum of fuss. In theory it should be capable of producing 1A at 12V, which is enough to light LEDs and charge phones. In this design there’s no battery charging circuit or anything like that, as [Nikola] says it’s up to the reader to figure out how to integrate the turbine into their system.

If you don’t think your 3D printing skills are up to the task, no worries. In the past we’ve seen wind turbines built out of ceiling fans, and occasionally, even less.

An MRI-Safe 3D Printed Pneumatic Stepper Motor

You will no doubt have seen those videos where MRI machines suck up all sorts of metallic objects with hilariously disastrous results. The magnetic field in one of these machines can easily pull in metal objects from across the room, exerting a force of several hundred pounds on any ferrous object unlucky enough to wander too close. As you can probably imagine, designing mechanical devices that can operate in such an intense magnetic field is exceptionally difficult.

But this fully 3D printed pneumatic stepper motor designed by [Foad Sojoodi Farimani] might one day change that. The PneuAct, which he presented at the recent International Conference on Robotics and Automation (ICRA) in Brisbane, Australia, manages to run at up to 850 RPM with full position control using bursts of air rather than electronic pulses. Made entirely of plastic and without any electronic components, the PneuAct can not only operate in intense magnetic fields but also areas with flammable gases where sparks could potentially cause an explosion.

We often say that a design is “fully” 3D printable, even though it might require screws or other bits of hardware. But in the case of the PneuAct, it’s truly all printed. It has to be, or else the whole thing would be ripped apart when it got to close to the MRI machine. Each and every piece of the motor is printed in ABS, and can be used without any additional machining or cleanup. No lubrication is required, and [Foad] mentions that the whole thing is so cheap that it can be disposable. Which is a huge advantage in medical environments where contamination could be a concern.

Design-wise the PneuAct is essentially an expanded version of the 3D printed air motors we’ve seen previously, but it would be fair to say that none has ever been studied so closely before.

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Smoothing PLA With Two Paints

There was a time when most 3D printers used ABS plastic. It stinks, is probably bad for you, and tends to warp unless printed in a heated enclosure. So most people have gone to something else, mostly PLA. But ABS also dissolves in a readily-available solvent, acetone, and this is useful for smoothing the layer artifacts from a 3D print. [3DSage] has a technique that works for PLA or — he says — probably any filament. You can see what he’s doing in the video below.

The video starts out with a recap of things most Hackaday readers will already know. But hang in there because at about 1:20, he reveals his method.

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Restoring An Atari 800 XL That’s Beyond Restoring

Sometimes the best way to get a hacker to do something is to tell them that they shouldn’t, or even better can’t, do it. Nothing inspires the inquisitive mind quite like the idea that they are heading down the road less traveled, if for nothing else to say that they did it. A thrown gauntlet and caffeine is often all that stands between the possible and the impossible.

Preparing the PCB for epoxy injection

So when [Drygol] heard a friend comment he had an old Atari 800 XL that was such poor shape it couldn’t be repaired, he took on the challenge of restoring the machine sight unseen. Luckily for us, his pride kept him from backing down when he saw the twisted and dirty mess of a computer in person. He’s started documenting the process on his blog, and while this is only the first phase of the restoration, the work he’s done already is impressive enough that we think you’ll want to follow him along on his quest.

There’s no word on what happened to this miserable looking Atari, but we wouldn’t be surprised if it was run over by a truck. The board was cracked and twisted, with some components missing entirely. The first step in this impossible restoration was straightening the PCB, which [Drygol] did by clamping it to some aluminum bar stock and heating the whole board up to 40C (104F) for a few days. Once the got most of the bend out, he used a small drill bit to put holes in the PCB laminate and inject epoxy to add some strength. It’s an interesting technique, and the results seem to speak for themselves.

Once the board was straight, he went through replacing blown passive components and broken chip sockets. All the ICs were pulled and treated to an isopropyl alcohol and acetone bath in an ultrasonic cleaner to get them looking like new again. The CPU was cooked and needed to get swapped out, but otherwise it was smooth sailing, and before long he had the machine booted up. While most would have been satisfied to just get this far, [Drygol] considers this to be the easy part.

He next straightened out the metal shielding with a mallet, sanded it down, and sprayed it with a new zinc coating. The plastic around the keyboard and the metal trim pieces were also removed, cleaned, and refinished where necessary. Rather than going for perfection, [Drygol] intentionally left some issues so the machine didn’t look 100% pristine. It’s supposed to be a functional computer, not a museum piece behind glass.

We’ll have to wait until the next entry in this series to see how he repairs the absolutely devastated case. Any rational person would just use a case from a donor machine, but we’ve got a feeling [Drygol] might have something a little more impressive in mind.

In the meantime we’ve got plenty of incredible restorations to keep you occupied, from this sunken VIC-20 to a Pi-packing Osborne.

Cams And Pushrods Improve 3D-Printed Compressed Air Engine

Some folks just can’t leave well enough alone, and that often ends up being a good thing. Such is the case with this 3D-printed compressed air engine, which just keeps getting better.

The design has changed a lot since we first covered [Tom Stanton]’s attempts at reviving the powerplant from the glory days of the Air Hogs line of toys, which he subsequently built a plane around. The engine was simple, with a ball valve that admitted air into the cylinder when a spring mounted to the top of the piston popped it out of the way. That spring has always bothered [Tom], though, compelling him to go back to the drawing board. He wanted to replace the ball valve with one actuated by a cam and pushrod. This would increase the complexity of the engine quite a bit, but with the benefit of eliminating the fail point of the spring. With a few iterations in the design, he was able to relocate the ball valve, add a cam to the crankshaft, and use a pushrod to open the valve. The new design works much better than the previous version, sounding more like a lawnmower than a 3D-printed engine should. Check out the design process and some tests in the video below.

And speaking of lawnmowers that run on compressed air

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3D Printing Watertight Containers

Most normal 3D prints are not watertight. There are a few reasons for this, but primarily it is little gaps between layers that is the culprit. [Mikey77] was determined to come up with a process for creating watertight objects and he shared his results.

The trick is to make the printer over extrude slightly. This causes the plastic from adjacent layers to merge together. He also makes sure there are several layers around the perimeters.

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