The Quest For The Reuleaux Triangle Bearing

April 30, 2018 by Ben James 22 Comments

[Angus Deveson] published a video on “solids of constant width” nearly a year ago. Following the release of the video, he had a deluge of requests asking if he could make a bearing from them. Since then, he’s tried a number of different approaches – none of which have worked. Until now…

What is a solid of constant width? A shape whose diameter is the same in all orientations, despite the fact that they aren’t circular. In particular, the Reuleaux Triangle is of interest; if you’ve heard of square drill bits, a Reuleaux Triangle is probably at play. Constructed from three circles, they make a neat geometrical study. When placed between two surfaces and rolled, the surfaces will stay parallel, despite the fact that the center of the triangle does not stay level.

In theory, this means they could be easily substituted for spheres in a classic roller bearing, but this turned out to be problematic – the first attempt determined how hard it was to get the shapes to roll instead of slide.

[Angus] finally arrived at a working bearing after a ton of suggestions from the community, and trying a number of attempts until he was able to achieve what he set out to do. The trick was to create a flexible insert (3D printed as well) for the center of the triangle edge, which grips the surfaces the triangle comes into contact with. A frame is also made to hold the bearings in place and allows their centers to move up and down as necessary.

If the thrill seeker within you still isn’t satisfied, maybe you should try the Reuleaux Coaster…

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Hard Drive Gives Its Life To Cool 3D Prints

April 29, 2018 by Mike Szczys 28 Comments

[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 fans article 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.

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Towards More Automated Printers

April 29, 2018 by Brian Benchoff 17 Comments

3D printers can be used in a manufacturing context. This might be surprising for anyone who has waited hours for their low-poly Pokemon print, but for low-volume plastic parts, you can actually run a manufacturing line off a few 3D printers. The problem with 3D printers is peeling the print off when it’s finished. If only there were a conveyor belt solution for a bed that wasn’t forgotten by MakerBot.

[Swaleh] may have a solution to the problem of un-automated 3D printers. He’s designing the WorkHorse 3D, a printer that uses a conveyor belt as a bed. When the print is finished, the conveyor belt rolls forward, depositing a printed part in a bin. It’s the solution to truly automated printing.

The use of conveyor belts to automate a batch of 3D prints isn’t a new idea. Way back in the Before Time, MakerBot released the Automated Build Platform, and used it in production to print off parts for Thing-O-Matics. This bit of Open Hardware was left by the wayside for some reason, and last year saw the invention of a new type of conveyor belt-based printer, The Infinite Build Volume Printer (for lack of a better name) from [Bill Steele]. This printer angles the print bed at 45 degrees, theoretically allowing for prints that are infinitely long. This idea was turned into the Printrbot Printrbelt, and the Blackbelt 3D printer was made public around the same time.

[Swaleh]’s printer is not of the infinite build volume variety. Instead of concentrating on creating long beams, most of the engineering work has gone into making a printer that’s designed to just push prints out. The conveyor belt bed is flat — and may unfortunately infringe on the MakerBot patents — but if you want a printer that’s designed to dump parts out like a very slow injection molding machine, this is the design you want.

The print queue application for this project is just a simple desktop app that serves as a buffer for G-code files. The app sends one G-code file off to the printer, rolls the bed forward, and queues up the next part. It’s simple, yes, but there aren’t too many things that do this now because there aren’t too many printers built to be factories. It’s impressive, and you can check out a few videos of this printer in action below.

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3D Printing Electronics Direct To Body

April 29, 2018 by Al Williams 11 Comments

Some argue that the original Star Trek series predicted the flip phone. Later installments of the franchise used little badges. But Babylon 5 had people talking into a link that stuck mysteriously to the back of their hand. This might turn out to be true if researchers at the University of Minnesota have their way. They’ve modified a common 3D printer to print electronic circuits directly to the skin, including the back of the hand, as you can see in the video below. There’s also a preview of an academic paper available, but you’ll have to pay for access to that, for now, unless you can find it on the gray market.

In addition, the techniques also allowed printing biologically compatible material directly on the skin wound of a mouse. The base printer was inexpensive, an Anycubic Delta Rostock that sells for about $300.

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2018’s Hottest Accessory Is A 3D Printed Air Raid Siren

April 27, 2018 by Lewin Day 11 Comments

Some say the spectre of global nuclear annihilation is closer than ever before. What better time to head to the workshop to prepare for the coming apocalypse? [MrExpert] is here with the build you need – an air raid siren you can print at home.

It’s a simple build, which makes it fun and accessible for just about anyone with a 3D printer. Rotational power is provided by a brushless outrunner motor hooked up to an ESC, controlled with a servo tester. The rotor and frame for the parts are 3D printed, and held together with a handful of standard fasteners.

Initial testing proves that yes, it does work and generates a rather earsplitting tone. The second revision improves upon this somewhat. However, the key to getting that authentic sound is in the sweep of the tone. By replacing the servo tester with an Arduino or other micro that can generate smoothly sweeping pulses to ramp the rotational speed up and down, you’ll get much closer to that genuine the-sky-is-falling timbre.

It’s certainly not rocket science, and would make a great project to whip up with the kids on a rainy weekend. While you’re at it you can share the wisdom behind the duck and cover technique, but maybe save the geopolitical rants for when they’re a bit older. We’ve seen air raid siren builds before, too – like this sturdy wooden unit.

Beat This Mario Block Like It Owes You Money

April 25, 2018 by Tom Nardi 13 Comments

People trying to replicate their favorite items and gadgets from video games is nothing new, and with desktop 3D printing now at affordable prices, we’re seeing more of these types of projects than ever. At the risk of painting with too broad a stroke, most of these projects seem to revolve around weaponry; be it a mystic sword or a cobbled together plasma rifle, it seems most gamers want to hold the same piece of gear in the physical world that they do in the digital one.

But [Jonathan Whalen] walks a different path. When provided with the power to manifest physical objects, he decided to recreate the iconic “Question Block” from the Mario franchise. But not content to just have a big yellow cube sitting idly on his desk, he decided to make it functional. While you probably shouldn’t smash your head into the thing, if you give it a good knock it will launch gold coins into the air. Unfortunately you have to provide the gold coins yourself, at least until we get that whole alchemy thing figured out.

Printing the block itself is straightforward enough. It’s simply a 145 mm yellow cube, with indents on the side to accept the question mark printed in white and glued in. A neat enough piece of decoration perhaps, but not exactly a hack.

The real magic is on the inside. An Arduino Nano and a vibration sensor are used to detect when things start to get rough, which then sets the stepper motor into motion. Through an ingenious printed rack and pinion arrangement, a rubber band is pulled back and then released. When loaded with $1 US gold coins, all you need to do is jostle the cube around to cause a coin to shoot out of the top.

If this project has got you interested in the world of 3D printed props from the world of entertainment, don’t worry, we’ve got you covered.

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Parametric Hinges With Tinkercad

April 23, 2018 by Al Williams 7 Comments

Simple tools are great, but sometimes it is most convenient to just use something easy, and since it gets the work done, you don’t try out some of the other features. Tinkercad is a great example of that kind of program. It is actually quite powerful, but many people just use it in the simplest way possible. [Chuck] noticed a video about making a 3D-printed hinge using Tinkercad and in that video [Nerys] manually placed a bunch of hinges using cut and paste along with the arrow keys for positioning. While it worked, it wasn’t the most elegant way to do it, so [Chuck] made a video showing how to do it parametrically. You can see that video below, along with the original hinge video.

There are really two major techniques [Chuck] shows. First, he adds the necessary pieces to create the hinges to the Tinkercad toolbox. That makes it really simple to add them to any of your future designs. Second, he uses a combination of numeric parameters and duplication to quickly and precisely place the hinge components across another object — in this case a Batman logo.

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