3D Printed Model Roller Coaster Accurately Simulates The Real Thing

December 30, 2021 by Robin Kearey 11 Comments

While they don’t give the physical thrill of a real one, model roller coasters are always fun to watch. However, they actually make a poor analog of a full-sized ride, as gravitational force and aerodynamic drag don’t scale down in the same way, model roller coasters usually move way faster than the same design would in the real world. [Jon Mendenhall] fixed this deficiency by designing a model roller coaster that accurately simulates a full-sized ride.

The track and cart are all made of 3D printed pieces, which altogether took about 400 hours to print. The main trick to the system’s unique motion is that the cart is motorized: a brushless DC motor moves it along the track using a rack-and-pinion system. This means that technically this model isn’t a roller coaster, since the cart never makes a gravity-powered drop; it’s actually a small rack railway, powered by a lithium-ion battery carried on board the cart. An ESP32 drives the motor, receiving its commands through WiFi, while the complete setup is controlled by a Raspberry Pi that runs the cart through a predetermined sequence.

The design of the track was inspired by the Fury 325 roller coaster and simulated in NoLimits 2. [Jon] wrote his own software to generate all the pieces to be printed based on outputs from the simulator. This included all the track pieces as well as the large A-frames holding it up; some of these were too long to fit in [Jon]’s 3D printers and had to be built from smaller pieces. The physics simulation also provided the inputs to the controller in the form of a script that contains the proper speed and acceleration at each point along the track.

The end result looks rather slow compared to other model roller coasters, but actually feels realistic if you imagine yourself inside the cart. While it’s not the first 3D printed roller coaster we’ve seen, it’s probably the only one that accurately simulates the real thing. If you’re more interested in a roller coaster’s safety systems, we’ve featured them too.

Continue reading “3D Printed Model Roller Coaster Accurately Simulates The Real Thing” →

several chocolate figurines of various sizes

Cast Your Own Holiday Chocolate Bunny, Or Rather Mouse

December 25, 2021 by Matthew Carlson 5 Comments

The art of forming and using a mold is, well, an art. The already tricky process would be made even harder by using a fickle material, like chocolate. This is exactly where [Alexandre Chappel] found himself as he tried to cast his own chocolate figurines.

The starting point was a 3D low-poly model of everyone’s favorite fictional electric mouse. He tweaked the model to add offsets so that after the model was vacuum formed, there would be something to clamp onto. [Alexandre] was left with four different pieces, and he vacuum-formed them with 1 mm PETG plastic. Electing for white chocolate to add coloring, he started heating the chocolate. Adding too much colorant resulted in a seized mess, so the process was a bit of trial and error. Finally, he poured in chocolate and spun it around to form an even layer of chocolate as a shell. The flashing lines were easy to trim with a utility knife.

The last thing to add was a little splash of color via airbrush and food-grade paint. The results are stunning, and even though the techniques are simple, the results came together nicely. The files are available on his website if you’re curious about making your own. If you’re curious about more clever casting techniques with chocolate, take a look at the creative use of diffraction grating to get iridescent chocolate.

Continue reading “Cast Your Own Holiday Chocolate Bunny, Or Rather Mouse” →

3D Prints With A Mirror Finish

December 25, 2021 by Matthew Carlson 15 Comments

As anyone who has used a 3D printer before knows, what comes off the bed of your regular FSD printer is by no means a mirror finish. There are layers in the print simply by the nature of the technology itself, and the transitions between layers will never be smooth. In addition, printers can use different technology for depositing layers, making for thinner layers (SLA, for example). With those challenges in mind, [AlphaPhoenix] set out to create an authentic mirror finish on his 3D prints. (Video, embedded below.)

As the intro hints, mirrors need very flat/smooth surfaces to reflect light. To smooth his prints, [AlphaPhoenix] first did a light sanding pass and then applied very thick two-part epoxy, allowing surface tension to do the smoothing work for him. Once dried, silver was deposited onto the pieces via a few different sprays. First, a wetting agent is applied, which prevents subsequent solutions from beading up. Next, he sprays the two precursors, and they react together to deposit elemental silver onto the object’s surface. [AlphaPhoenix] asserts that he isn’t a chemist and then explains some of the many chemical reactions behind the process and theorizes why the solutions break down a while after being mixed.

He had an excellent first batch, and then subsequent batches came out splotchy and decided un-mirror-like. As we mentioned earlier, the first step was a wetting agent, which tended to react with the epoxy that He applied. Then, using a grid search with four variables, [AlphaPhoenix] trudged through the different configurations, landing on critical takeaways. For example, the curing time for the epoxy was essential and the ratio between the two precursor solutions.

Recently we covered a 3D printed mirror array that concealed a hidden message. Perhaps a future version of that could have the mirror integrated into the print itself using the techniques from [AlphaPhoenix]?

Continue reading “3D Prints With A Mirror Finish” →

Do You Need A Cycloidal Drive?

December 25, 2021 by Elliot Williams 10 Comments

A cycloidal gear drive is one of the most mesmerizing reduction gears to watch when it is running, but it’s not all just eye-candy. Cycloidals give decent gearing, are relatively compact and back-drivable, and have low backlash and high efficiency. You probably want one in the shoulder of your robot arm, for instance.

But designing and building one isn’t exactly straightforward. Thanks, then, to [How To Mechatronics] for the lovely explanation of how it works in detail, and a nice walkthrough of designing and building a cycloidal gear reducer out of 3D printed parts and a ton of bearings. If you just want to watch it go, check out the video embedded below.

The video is partly an ad for SolidWorks, and spends a lot of time on the mechanics of designing the parts for 3D printing using that software. Still, if you’re using any other graphical CAD tool, you should be able to translate what you learned.

It’s amazing that 3D printing has made sophisticated gearbox designs like this possible to fabricate at home. This stuff used to be confined to the high-end machine shops of fancy robotics firms, and now you can make one yourself this weekend. Not exotic or unreliable enough for you? Well, then, buy yourself some flexible filament and step on up to the strain wave, aka “harmonic drive”, gearbox.

Thanks to serial tipster [Keith] for the tip!

Continue reading “Do You Need A Cycloidal Drive?” →

ESP8266 Based WiFi Game Boy Cartridge Browses WikiPedia

December 18, 2021 by Dave Rowntree 8 Comments

[Sebastian Staacks] came across his old Game Boy and was wondering (as you do) what happened to recent attempts at getting a WiFi interface wedged into a standard cartridge. After a while the conclusion was that people had been scuppered by approaching the problem in a way that made it too hard. Obviously that meant it was necessary to follow through and build something, which is precisely what he did with his WiFi Game Boy Cartridge.

A trend lately has been to hook up a fast microcontroller to a bus, then move the whole interfacing shenanigans into software. This works fine in some circumstances, but for the GB interface, it’s not so easy. The GB is powered by the Sharp LR35902, running at a smidge over 4 MHz, but its machine cycle takes four clocks giving an instruction rate of only 1 MHz. The cartridge interface presents the raw CPU bus directly. This is both good and bad. It’s good, because it enables all kinds of expansion modules, like cameras, printers, and other custom peripherals, but it’s bad because the burden of interfacing with the CPU, at its full speed, lies squarely in the cartridge’s remit.

Rather than trying to hook this bus directly to a fast microcontroller, [Staacks] has taken a different approach; by decoding the address bus with discrete logic, it was easy to derive chip selects for an embedded ESP8266 as well as a socketed EEPROM. The clock for the former was also gated and sent into the ESP8266, generating an interrupt to wake it up. The EEPROM stores a simple application whose job is to present an OSD keyboard and send requests to Wikipedia, via the ESP8266 WiFi stack. The resulting text is then displayed on the 160×144 dot matrix display. The interrupt latency of the ESP8266 was mitigated by the application simply discarding the first data byte sent to it, and retrying the access. This way the ESP8266 could spend the majority of its time dealing with wireless duties, only pausing to swap a byte now-and-then with the application. A simple solution which appears to actually work! If you’re up for building one of these and writing your own applications, you can wander over to GitHub, clone yourself a copy and crack on!

We’ve seen a few attempts at doing this before, [davedarko] tried with this project, and if you search hackaday.io you’ll get loads of GB hacks to browse. Finally a recent twitter thread also points to another effort to do something similar with Wi-Fi, but development is still ongoing. We’ll check back later!

Continue reading “ESP8266 Based WiFi Game Boy Cartridge Browses WikiPedia” →

DIY Mechanical Flux Dispenser Syringe Has Fine Control

December 17, 2021 by Donald Papp 16 Comments

[Perinski]’s design for a mechanical flux dispenser uses some common hardware and a few 3D printed parts to create a syringe with fine control over just how much of the thick stuff gets deposited. The design is slick, and there’s a full parts list to accompany the printed pieces. [Perinski] even has some useful tips on how to most effectively get flux into 5 mL syringes without making a mess, which is a welcome bit of advice.

There is also a separate companion design for a magnetic syringe cap. Not only does it have an O-ring to keep things sealed and clean, but the tip of the cap has a magnet embedded into it, so that it can be stowed somewhere safe while the dispenser is in use, and doesn’t clutter the workspace.

This is all a very interesting departure from the design of most syringe dispensers for goopy materials, which tend to depend on some kind of pneumatic action. Even so, we’ve also seen that it’s possible to have a compact DIY pneumatic dispenser that doesn’t require a bulky compressor.

If you can’t quite figure out how the ergonomics of [Perinski]’s design are intended to work one-handed, you’re not alone. One holds the syringe in their hand, and turns the large dial in small increments with a thumb to control extrusion. [Perinski] demonstrates it close-up around the 4:50 mark, but if you have a few minutes it is worth watching the entire video, embedded below.

Continue reading “DIY Mechanical Flux Dispenser Syringe Has Fine Control” →

A Nested Gear Clock

December 12, 2021 by Matthew Carlson 11 Comments

One of the most common projects we see here at Hackaday is a clock. It could just be that we as humans are fascinated by the concept of time or that making a piece of functional art appeals to our utilitarian sense. In that spirit, [Alexandre Chappel] set out to make a large mechanical clock with complex gears.

The initial design was made in Fusion360 over a week and then in a somewhat bold move, [Alexandre] started up the CNC and cut all the parts out of valchromat. The basic idea of the clock is that the numbers move on the clock, not the hands. So the clock should show 10:25 instead of moving hands to the 10 and the 5. Most of the clock is made of up stacked gear assemblies, geneva drives, and many bearings. A single stepper motor drives the whole clock, which [Alexandre] admits is a bit of a cheat since trying to add springs and an escapement would add complexity to an already complex clock. He did have to adjust and recut a few gears but most of the assembly came together nicely. Some 3d printed numbers dropped into the CNCed slots offers much-improved readability.

A few problems became apparent once the system was together. The numbers don’t quite line up perfectly, which is unfortunate. He mentioned that tighter tolerances on the gears would likely help there. A fatal design flaw on the smallest disk became apparent as it needs to turn a sixth of the circle whereas the outer circle is just turning a tenth of the circle. Mechanical advantage isn’t in [Alexandre’s] favor and the stepper skips some steps and it slowly makes its way towards the next second digit of the hour.

If you’re looking for more beautiful artistic clocks, why not check out this circuit sculpture one?

Continue reading “A Nested Gear Clock” →