Fail Of The Week: Hard Lessons In 3D-Printed Bushings For A Giant RC Car

December 25, 2018 by Dan Maloney 18 Comments

Can you turn 47 pounds (21 kg) of PLA filament into a gigantic working 3D-printed RC car? No, no you can’t — at least not if you eschew proper bearings in favor of printed bushings.

That’s the hard lesson that [Joel Telling] learned with his scaled up version of the OpenRC F1 car, an RC car that can be mostly 3D-printed. The small version still has its share of non-printed parts, mainly screws and bearings. In his video series documenting the build of the upsized version, [Joel] elaborates on some of the reasons for going with printed bushings rather than bearings, which mainly boil down to hoping that the graphite lubricant powder he added would reduce friction enough to prevent the parts from welding themselves together.

The car came out looking great, and even managed to scoot about nicely for a few seconds before its predictably noisy and unhappy demise. But what was unexpected was the actual failure mode. The plastic-on-plastic running gear seemed to handle the rolling loads fine; it was the lateral force exerted on the axle by the tension of the drive belt that was too much for the printed bushing to bear.

As [Joel] rightly points out, it’s only a failure if you fail to learn something, so kudos to him for at least giving this a try. And all that PLA won’t go to waste, of course — everything else on the car worked fine, so adding one bearing should get it back on the road. He should check out our primer on bearings for a few tips on selecting the right one.

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Henry The Hoover Gets A Weapons Upgrade

December 1, 2018 by Lewin Day 12 Comments

In this day and age of unprecedented military expenditure, we’re used to seeing weapons upgrades across all manner of war fighting hardware – tanks, helicopters, attack aircraft, you name it. We’re somewhat less accustomed to seeing the same on a domestic appliance. Regardless, we now have Henry the Hoover packing some serious heat.

Originally a mere vacuum cleaner, Henry was given movement through two motors and gearboxes sourced from a children’s ride on vehicle. A tank was created out of copper pipe to store the flammable gas (which appears to be butane, as used in cigarette lighters), and discharge is controlled with a solenoid valve. Ignition is then handled by a pair of electric ignitors fired by relay. It’s all controlled over a standard hobby radio controller, so you can stand at a safe distance while flambeeing your rug.

It’s a dangerous project, but one that is particularly fun when Henry’s dazed and amused countenance is taken into account. But then again, you might like your flamethrowers wrist mounted, instead. Video after the break.

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9 Planes Combine To Make One Giant Flexible Flier

November 28, 2018 by Adam Fabio 18 Comments

[Ran D. St. Clair] has created a unique flying machine in the Flex 9. It’s not every day that you see a completely new and unusual aircraft, but the Flex 9 definitely fits the bill. [Ran] took 9 radio controlled planes, connected them together, and made one giant plane — and with an 18-foot wingspan, giant isn’t a misnomer.

The planes that make up the Flex 9 are simple aircraft – foamboard wings, a boom, and a basic tail. The individual planes only have elevator control – no rudder, no ailerons. Power comes from a standard LiPo battery, ESC and brushless outrunner motor. The control system is interesting – every plane has a KK board flight controller running OpenAeroVTOL firmware. The center plane has a radio receiver and communicates to the other KK boards over standard servo wires. Rudder (yaw) and aileron (bank) control are achieved through mixing handled by flight controllers.

Even the couplings between the planes were carefully designed. [Ran] used an EPP foam core as a rubbery dampener, with plywood to strengthen the joint. Each joint is mounted at a 20-degree angle. As the planes bank relative to each other, the angle forces the airframe to twist, which should help the whole system stay level.

Check out the videos below for an explanation and a flight test. The Flex 9 launch isn’t exactly stable – there’s some crazy sinusoidal wobbling going on. But the mechanical and electronic dampeners quickly spring into action smoothing the flight out.

If you’d like to know more about the KK board, you can read about right here.

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Foam Airboat Is Cheap RC Fun

November 15, 2018 by Lewin Day 7 Comments

Archer fans and residents of Louisiana will already be familiar with the concept of the airboat. Put a powerful engine running an aircraft prop on a flat-bottomed hull, and you’ve got an excellent way to traverse the marshes of the American South. While a fully-fledged airboat might run you the best part of $100,000, this no-frills radio-controlled version is great fun at a much lower price.

The hull is built on a sheet of foam, which is cheap, readily available, and suitably buoyant for the task. It’s then kitted out with a brushless motor to run the prop and a servo to control the rudder. Lace it up with a radio receiver and speed controller and you’re good to go.

The build could readily be completed in well under a couple of hours, and is a great one to tackle with kids due to its mechanical simplicity. There’s room for extra creativity too – you can always substitute a watermelon if you’re feeling peckish. Video after the break. Continue reading “Foam Airboat Is Cheap RC Fun” →

Centurion Bridge Layer, Now In RC

November 14, 2018 by Lewin Day 1 Comment

Radio controlled models are great fun. Most of us have had a few RC cars as children and maybe dabbled with the occasional helicopter or drone. It’s a rare breed of modeler, however, that gets to drive a radio-controlled bridge laying tank.

The lads prepare to fight the good fight.

The model is a replica of the British Centurion Bridgelayer – a modified tank designed to allow mechanized units to readily cross rivers and similar obstacles in European battlefields. While the genuine article relied on hydraulics, the RC version takes a different tack. [hawkeye3guns] built custom linear actuators out of motors, gears, and brass to deploy the bridge.

The build shows other smart techniques of the enterprising modeler. Rather than start from scratch, the Centurion is built on a modified KV tank hull. After the modifications were complete, the tank received a lick of paint in the requisite British Army green. The final result is rather impressive.

It goes to show what can be achieved with some off-the-shelf parts and ingenuity. We’ve seen other impressive RC tanks before – like this French build with a homebrew targeting computer.

RC Boat Goes Brushless For Speed & Reliability

August 24, 2018 by Lewin Day 17 Comments

Remote control boats can be great fun, and come in all manner of forms. There are unpowered sailcraft, speedboats that scream under the power of internal combustion, and of course, those that move under electric power. The brushless motor revolution of the past 20 years in particular has proven capable of creating some exciting RC watercraft, and [Matt K] decided he wanted to get on board.

[Matt] had owned a Kyosho Jetstream 1000 for several years, but found the nitro engine to be temperamental and not the most fun for high-jinx down at the lake. An old-school brushed motor setup with mechanical speed control similarly failed to excite. However, after experiencing the power of brushless in RC planes, [Matt] knew what he had to do.

Using an online calculator, [Matt] determined that his earlier nitro powerplant was putting out roughly 900 watts. When it came to going brushless, he decided to spec a Turnigy powerplant with twice as much power, along with the requisite speed controller. There was some work to do to integrate the new motor with the original propeller driveshaft and water cooling system, but in the end [Matt] ended up with a much faster boat that is a lot less hassle to set up and run.

Perhaps though, your RC boat needs brains, over brawn? Perhaps it’s time to look at autonomy…

Video after the break.

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Giant F1 Car Is 3D Printed And Radio Controlled

April 2, 2018 by Lewin Day 16 Comments

The OpenRC F1 car is a radio control car you can 3D print and assemble yourself. You make the parts, glue them together, and then add your RC gear. That’s all well and good, but could it be done… bigger? [3D Printing Nerd] decided to tackle this one at 4x scale.

It goes without saying that this took some work. The model has to be carved up into sections that would actually fit on the printers to hand. This can take some planning to ensure the parts still come out nicely, as they may be printed in different orientations or with different slicer settings than originally intended.

That’s just the start, though. Once they’re printed, the parts need to be accurately aligned and glued together, which is a whole extra set of challenges. Urethane, epoxy and superglue adhesives are all pressed into service here to get the job done.

It’s a multipart build, as it’s a huge undertaking to 3D print anything on this scale. It’s a great example of taking a fun project, and turning up the silly factor to 11. And of course, at the end of the day, you’ve got a gigantic RC car to play with. Perhaps the only bigger RC cars we’ve seen have been… actual cars.