Complex Movements From Simple Inflatables, Thanks To Physics

July 24, 2022 by Donald Papp 5 Comments

Inflatable actuators that change shape based on injected pressure can be strong, but their big limitation is that they always deform in the same way.

The Kresling pattern, which inspired the actuator design.

But by taking structural inspiration from origami, researchers created 3D-printed actuators that show it is possible to get complex movements from actuators fed by only a single source of pressure. How is this done? By making the actuators physically bi-stable, in a way that doesn’t require additional sources of pressure.

The key is a modified design based on the Kresling pattern, with each actuator having a specially-designed section (the colored triangles in the image above) that are designed to pop out under a certain amount of positive pressure, and remain stable after it has done so. This section holds its shape until a certain amount of negative pressure is applied, and the section pops back in.

Whether or not this section is popped out changes the actuator’s shape, therefore changing the way it deforms. This makes a simple actuator bi-stable and capable of different movements, using only a single pressure source. Stack up a bunch of these actuators, and with careful pressure control, complex movements become possible. See it in action in two short videos, embedded just below the page break.

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Automated Hotend Swapping For Less Wasteful Multicolor Printing

July 24, 2022 by Danie Conradie 16 Comments

Multicolor printing on FDM machines can be tricky to get working flawlessly, and purging hotends when changing colors can end up wasting a lot of filament and material. To solve this problem for the popular Prusa i3 and Ender 3 printers, [BigBrain3D] developed the Swapper3D, an automated system that swaps the entire hotend when the material is changed, eliminating the need for purging almost entirely. Video after the break.

The Swapper3D works very similarly to the tool-changing systems on CNC machines, and is just as satisfying to watch. A large circular carousel on the side of the machine holds up to 25 hotends, and in practice, a pair of robotic arms pop out the previous hotend, cut the filament, and load up the specified hotend from the carousel. This means you can have a separate hotend for each color or type of filament. Since most existing hotends also integrate the heating element, [BigBrain3D] created a special hotend assembly that can be robotically removed/inserted into the heater block.

The Swapper3D is designed to be used with existing filament changers like the Prusa MMU and the Mosaic Palette. Using these systems involves a lot of purging, to the point where you sometimes end up using more filament during purging than you need for the actual part. On one five-color demo print, the Swapper3D reduced the print time by 45% and the filament used by a massive 86%. It also helps to eliminate problems like stringing and color fading in multicolor prints. With those advantages, it looks like the Swapper3D might be a worthwhile upgrade if you do a lot of multi-color printing, even though it adds quite a bit of complexity to the printer.

For larger, more expensive machines, swapping the entire toolhead is becoming more popular, with even E3D stepping into the fray.

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A 3D printed roller coaster model with light strips modelling the trains

How To Make A Model Roller Coaster Without Any Moving Parts

July 20, 2022 by Robin Kearey 5 Comments

Roller coasters are not only great fun to ride, they’re also fascinating pieces of engineering. Building your own full-size coaster is sadly beyond most people’s means, so the average enthusiast will have to settle for simulation or modelling of their own designs. [Jon Mendenhall] is one of those who specialize in building model roller coasters and simulating their motion in intricate detail. His latest project is a scale model of VelociCoaster, a Jurassic Park-themed ride in Universal’s Islands of Adventure, that simulates the coaster’s ride without using any moving parts.

[Jon] achieves this by re-creating the trains’ motion using LED strips. A total of 3000 LEDs are spread along more than nine meters of track and make a mesmerizing light show of several trains whizzing along the track, accelerating and slowing down exactly like the real thing.

In his video, [Jon] explains the process of generating an accurate 3D model of the track starting from nothing more than an overhead view of the park as well as photos taken from various angles. The surrounding terrain and buildings are also included in his 3D model, as are the 128 supports that hold the track in place. The terrain and building were made from plywood and foam using a CNC machine, while the track and supports were 3D printed.

A Teensy microcontroller runs the whole show, with the LED strips split into five separate sections to allow a high enough frame rate for smooth animations. An infrared remote is used to start and stop the ride, as well as to adjust the speed; the model supports running the trains at a physically accurate speed, but because this looks rather dull, the regular setting is about three times as fast.

Looking for more roller coaster models? [Jon] made a similarly impressive model with a powered train before, and we’ve seen several models that actually coast along their tracks.

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3D Printed Skate Trucks Do Surprisingly Okay

July 20, 2022 by Lewin Day 18 Comments

If you can buy something off the shelf, there’s a good chance that someone has tried to 3D print their own version. [Daniel Norée] did just that with skateboard trucks, whipping up a design of his own.

The main body of the trucks is 3D-printed, as is the hanger. A 195 mm M8 threaded rod is then used through the center of the trucks in order to provide an axle for fitting the wheels and bearings themselves. He 3D-printed the parts using a carbon-fiber reinforced nylon with the slicer set up to maximize strength. In testing, they rolled around the neighbourhood just fine.

[Mayer Makes] found the design online, and 3D printed some using his own transparent high-impact resin, making a cool set of clear-ish trucks. It’s a tough material, which we’ve featured on this site before.

Those trucks ended up in the hands of [Braille Skateboarding], who put them through their paces. The trucks are loose, but take a good beating around the park. Eventually one of the trucks succumbs after landing many kickfilps and ollies on the concrete.

Other great skate hacks include casting your own wheels in a 3D-printed mold. Video after the break.

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Ask Hackaday: Resin Printer Build Plates

July 20, 2022 by Al Williams 29 Comments

The early days of FDM 3D printing were wild and wooly. Getting plastic to stick to your build plate was a challenge. Blue tape and hairspray-coated glass were kings for a long time. Over time, better coatings have appeared and many people use spring steel covered in some kind of PEI. There seem to be fewer choices when it comes to resin printers, though. We recently had a chance to try three different build surfaces on two different printers: a Nova3D Bene4 and an Anycubic Photon M3. We learned a lot.

Resin Printing Review

If you haven’t figuratively dipped your toe into resin yet — which would literally be quite messy — the printers are simple enough. There is a tank or vat of liquid resin with a clear film on the bottom. The vat rests on an LCD screen and there is a UV source beneath that.

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Liquid Piston Engine Finally Works

July 15, 2022 by Al Williams 7 Comments

The first video from [3DPrintedLife] attempting to make a liquid piston engine was… well… the operative word is attempting. The latest video, though, which you can see below gets it right, at least eventually.. He has a good explanation of the changes that made the design better. Turns out, one change that made a difference was to turn a key part of the engine inside out. You can see the video below.

The first version would quickly break during operation and while the first new version didn’t work very well, it did stay in one piece which is a definite improvement.

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You Wouldn’t 3D Print A House, Would You?

July 13, 2022 by Matthew Carlson 66 Comments

Most houses built in the US today are platform construction: skinny two-by-fours are stacked and layered to create walls with studs. Each floor is framed on top of the other. It is fast, relatively cheap, and easy to learn how to do. However, it is not without drawbacks. Some estimates put the amount of waste generated per square foot (0.09 m²) at around 3.9 lbs (1.8 kg).

Timber framing is an older style where giant beams are used to create the structure of the house. Each timber is hand-carved and shaped, requiring skill and precision. Some cabins are still built this way because it is easy to source the timber locally and cutting into big logs is less work than cutting into lots of small logs. It’s relatively ecologically friendly, but slow and skilled-labor intensive.

We live in a world where there is a vast need for cheaper, faster, more eco-friendly housing, but finding a solution that can tick all the boxes is fiendishly difficult. Can 3D-printed housing accomplish all three of those goals? We’re not there yet, but we’re working on it.

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