Walk The First 3D-Printed Bridge And Be Counted

Way back in 2018, we brought you news of a 3D-printed stainless steel pedestrian bridge being planned to span a Dutch canal in Amsterdam. Now it’s finally in place and open to the public — the Queen made it official and everything. MX3D printed it on their M1 Metal additive manufacturing machine that is essentially a group of robots welding layers of metal together using traditional welding wire and gas.

The partnership of companies involved originally planned to build this beautiful bridge in situ, but safety concerns and other issues prevented that and it was built in a factory instead. The bridge has been printed and ready since 2018, but a string of delays got in the way, including the fact that the canal’s walls had to be refurbished to accommodate it. Since it couldn’t be made on site, the bridge was taken there by boat and placed with a crane. After all this, the bridge is only permitted to be there for two years. Hopefully, they have the option to renew.

This feat of engineering spans 40 feet (12.2 meters) long and sits 20 feet (6.3 meters) wide. It’s equipped with sensors that measure structural stuff like strain, displacement, load, and rotation, and also has environmental sensors for air quality and temperature. All of this data is sent to the bridge’s digital twin, which is an exact replica in the form of a computer model. One of the goals is to teach the bridge how to count people. Be sure to check out our previous coverage for a couple of short videos about the bridge.

3D Printed Roller Coaster Looks Pretty Darn Fun

Rollercoasters are great fun if you can deal with the exhilaration without throwing up or otherwise screaming until you pass out. Of course, the big outdoors ones are a little hard to get to at the moment, what with a pandemic raging outside. However, [3d_coasters] has built a tabletop design that, while it’s too small to ride, is nonetheless quite impressive. (Video, embedded below.)

The coaster is of the launch design. It relies on an elastic cord that is wound up to high tension to launch the train up to speed, with the train then coasting around the rest of the curves on the track. The quality of the modelling is highly impressive, too. The doors at the boarding platform are even actuated to simulate riders boarding the train! Everything is controlled by an Arduino, a handful of micro servos, and a DC motor.

As you might imagine, this project didn’t happen overnight. 600 hours were logged in Fusion 360 developing the track, and slicing the models in Cura for 3D printing took a further 5 hours. The actual printing process itself took 800 hours, not including finishing, so this project certainly isn’t one for the faint of heart. The final model weighs a full 30 lbs.

Believe it or not, we’ve featured 3D printed rollercoasters before, too. Video after the break.

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Modified 3D-Printer Solders Through-Hole Components

Surface-mount technology has been a fantastic force multiplier for electronics in general and for hobbyists in particular. But sometimes you’ve got no choice but to use through-hole components, meaning that even if you can take advantage of SMDs for most of the design, you still might need to spend a little time with soldering iron in hand. Or not, if you’ve got a spare 3D printer lying around.

All we’ve got here is a fairly brief video from [hydrosys4], so there aren’t a lot of build details. But it’s pretty clear what’s going on here. Starting with what looks like a Longer LK4 printer, [hydrosys4] added a bracket to hold a soldering iron, and a guide for solder wire. The solder is handled by a more-or-less standard extruder, which feeds it into the joint once it’s heated by the iron. The secret sauce here is probably the fixturing, with 3D-printed jigs that hold the through-hole connectors in a pins-up orientation on the bed of the printer. With the PCB sitting on top of the connectors, it’s just a matter of teaching the X-Y-Z position of each joint, applying heat, and advancing the solder with the extruder.

The video below shows it in action at high speed; we slowed it down to 25% to get an idea of how it is in reality, and while it might not be fast, it’s precise and it doesn’t get tired. It may not have much application for one-off boards, but if you’re manufacturing small PCB runs, it’s a genius solution. We’ve seen similar solder bots before, but hats off to [hydrosys4] for keeping this one simple.

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Injection Molds From Your 3D Printer

Last time we checked in with [CrafsMan] he had bought a benchtop injection molding machine. This time, he shows off how to 3D print molds. If you have ever had to spend to make tooling for injection molding, you’ll appreciate being able to make molds relatively inexpensively.

To test his workflow, [CrafsMan] created a little 3D figurine and brought it into TinkerCad. From there he created a mold and used Lychee Slicer to print it using resin.

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DIY Fume Extractor Keeps Air Clean While You Solder

Soldering is a key skill to learn when building electronics, but it’s also a process that can put out a lot of fumes. The best way to deal with this is to use a fume extractor. Of course, you can always make your own, as [Open Green Energy] ably demonstrates. It’s a guided build of the design [rdmmkr] published on Thingiverse.

The build relies on a 120mm case fan for suction, and it’s combined with a activated carbon filter to best capture the harmful fumes from the soldering process. The fan is neatly installed inside a 3D printed enclosure of custom design, which also includes a removable tray which holds the filter material. The fan is run from a DC power supply via a barrel jack, and a basic speed controller is installed to allow the fan to be turned up higher for more suction, or lower to reduce noise.

It’s a useful item to have around the home workshop, and it’s something that you could easily whip up at home with parts from the junk bin if you’re so inclined. The benefit of 3D printing is that you can easily alter the design to suit whatever parts you have on hand.

We’ve seen a few fume extractor builds over the years, from the simple and basic to the very fancy. Video after the break.

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DIY Camera Dolly Costs More Time Than Money

A camera dolly can be fantastic filmmaking tool, and [Cornelius] was determined to create his own version: the “Dope” DIY Dolly. The result not only upped his production quality, but was also entirely in line with his DIY approach to filmmaking in general.

A basic dolly design is straightforward enough: a flat platform with wheels, and some aluminum tubing upon which to roll. But while dolly assemblies are easy to purchase or rent, [Cornelius] found that his DIY version — which used easily sourced parts and about 80 hours worth of 3D printing — provided perfectly acceptable results, while opening the door to remixing and sharing with like-minded filmmakers.

Interested? Download the STL files to get started on your own version. As for the track, smooth metal pipe is best, but sometimes track made from PVC can do the job. [Cornelius] has a few additional STL files for those planning to make a base from 1″ PVC pipe, and those are on a separate download link near the bottom of the project page (here’s that link again.) Watch the Dope Dolly in action in the brief video embedded below.

On the other hand, if you prefer your DIY camera equipment to be on the smaller and more complicated end of the spectrum, be sure to check out this multi-axis camera slider.

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SOL75 Uses AI To Design Standard Mechanical Parts

[Francesco] developed a parametric design tool called SOL75 which aims to take the drudgery out of designing the basic mechanical parts used in projects. He knows how to design things like gears, pulleys, belts, brackets, enclosures, etc., but finds it repetitive and boring. He would rather spend his time on the interesting and challenging portions of his project instead.

The goal of SOL75 is to produce OpenSCAD and STL files of a part based on user requirements. These parameters go beyond the simple dimensional and include performance characteristics such as peak stress, rigidity, maximum temperature, etc. The program uses OpenSCAD to generate the geometries and a core module to evaluate candidate designs. In an attempt to overcome the curse of dimensionality, [Francesco] has trained an AI oracle to quickly accept or reject candidate solutions.

In the realm of parametric design aids, you have projects like NopSCADlib which dimensionally parameterize a large collection of common objects by numbers alone ( a 100 cm long, 6.35 mm diameter brass tube with 1.22 mm wall thickness ) or industry standard specifications ( a 10 mm long M3 socket head cap screw ). This approach doesn’t take into account whether the object will hold up in your application nor does it consider any 3D printing issues. At the other extreme, there are the generative design and optimization tools found in professional packages like Fusion 360 and SolidWorks which can make organic-looking items that are optimized precisely for the specified conditions.

SOL75 seems to fall in the middle, combine characteristics of both approaches. It gives you the freedom to select dimensional parameters and performance requirements, yet bounds the solution space by only offering objects that have been prepared ahead of time by domain experts — if you ask for an L-bracket, you’ll get an L-bracket and not something that looks like a spider web or frog leg.

Once you compile the design, SOL75 generates the OpenSCAD and/or STL files and a bill of materials. But wait — there’s more– it also makes a thorough design handbook documenting the part in great detail, including the various design considerations and notes on printing. Here is a demonstration link for an electronics enclosure which is pretty interesting. There is also an example of using SOL75 to make a glider, which you can read about on the Hackaday.io project page.

For now, [Francesco] has only made SOL75 available in a register-by-email online Beta version, as he’s still undecided on what form the final version will be. Do you have any success (or failure) stories regarding generative designs? Let us know in the comments below.