3D Printed Rigid Chain Mechanism

December 8, 2020 by Danie Conradie 34 Comments

One of the major advantages of 3D printing is the ability to quickly test and then iterate on mechanical designs. [gzumwalt] does a lot of this, and has recently been working on various versions of a rigid chain mechanism. (Video, embedded below.)

A rigid-chain mechanism is one way of fitting a long beam into a small box. It works similar to a zipper, meshing two separate “chains” with specially teeth designed to form a rigid beam. Due to clearances between the teeth, the beam tends to be a bit floppy. [gzumwalt] made various sizes of the mechanism, and also reduced the clearances on later versions to reduce the flop. He also integrated it into a cool “snake in a basket” automaton (second video below) by adding a reversible gearbox and a binary snap-action switch.

One possible use for this type of mechanism is for autonomously assembling long structures in space, as one of the 2017 Hackaday Prize finalist projects, ZBeam, proposed.

[gzumwalt] has not made the files available for download yet, but you can keep and eye on his Instructables pages for updates. He got a number of fascinating 3D printed devices already available, like a domino laying machine or a WiFi controlled rover.

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Food Safe Printing Techniques

December 7, 2020 by Al Williams 10 Comments

One thing that always provokes spirited debate around the Hackaday bunker is just how dangerous is it to use 3D printed plastic in contact with food. We mostly agree it isn’t a good thing, but we also know some people do it regularly and they don’t drop dead instantly, either. [Jakub] decided to do some testing and make some recommendations. There’s even a video explaining the results.

Unlike a lot of what we’ve read about this topic in the past, [Jakub’s] post is well-researched and does actual testing including growing bacteria cultures from cups used for milk. He starts out identifying the EU and US regulations about what you can call food-grade. There’s also recognition that while a base plastic might be safe for contact with food, there’s no way to know exactly what additives and other things are in the plastic to change its properties and color.

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A Case For Project Part Numbers

December 2, 2020 by Sonya Vasquez 32 Comments

Even when we share the design files for open source hardware, the step between digital files and a real-world mechatronics widget is still a big one. That’s why I set off on a personal vendetta to find ways to make that transfer step easier for newcomers to an open source mechantronics project.

Today, I want to spill the beans on one of these finds: part numbers, and showcase how they can help you share your project in a way that helps other reproduce it. Think of part numbers as being like version numbers for software, but on real objects.

I’ll showcase an example of putting part numbers to work on one of my projects, and then I’ll finish off by showing just how part numbers offer some powerful community-building aspects to your project.

A Tale Told with Jubilee

To give this idea some teeth, I put it to work on Jubilee, my open source toolchanging machine. Between October 2019 to November 2020, we’ve slowly grown the number of folks building Jubilees in the world from 1 to more than 50 chatting it up on the Discord server. Continue reading “A Case For Project Part Numbers” →

Advanced Printer Control Aims To Stop Idle Waste

November 29, 2020 by Lewin Day 21 Comments

3D printers are capable of creating complex geometries with a minimum of fuss, but one of the tradeoffs is the long period of time it takes to print a part. Often, printers are left to run for many hours with a minimum of supervision to complete their tasks. This can leave printers idling for long periods of time after their work is finished. Noting this, [TheGrim] put together the Advanced Printer Control.

The aim of the APC is to monitor 3D printers, and shut them off when their work is complete. The aim is to avoid leaving printers running for hours after their prints are finished, which causes needless wear on fans and screens which can have a limited life. This is achieved by putting an ESP8266 in charge of the printer’s AC power supply, via a triac. It measures the current drawn by the printer when idling and in use to set a baseline. Then, whenever the printer drops back to idle levels, a timer begins. When the timer runs out, the printer is switched off. There’s also an option to automatically trigger shutdown with an I/O pin, too.

It’s a project that aims to extend printer life and save power, too. Of course, if you’re really worried about power draw, you could use a solar powered printer instead. If you’ve got your own printer controller hacks, be sure to drop us a line.

Cleaner Laser Cutting With A 3D-Printed Nozzle

November 25, 2020 by Donald Papp 24 Comments

[Nervous System] does a lot of laser cutting, and [Jesse] shared a fascinating experimental improvement to their laser cutter that consists of a 3D-printed nozzle for cleaner cuts. You can see the results for yourself above, where the difference between the two cuts is striking.

[Jesse]’s modification doesn’t affect the laser beam itself; it is an improvement on the air assist, which is the name for a constant stream of air that blows away smoke and debris as the laser burns and vaporizes material. An efficient air assist is one of the keys to getting nice clean laser cuts, but [Jesse] points out that a good quality air assist isn’t just about how hard the air blows, it’s also about how smoothly it does so. A turbulent air assist can make scorch marks worse, not better.

3D-printed nozzle to promote laminar air flow on the left, stock nozzle on the right.

As an experiment to improve the quality of the air flowing out the laser nozzle, [Jesse] researched ways to avoid turbulence by creating laminar flow. Laminar flow is the quality of a liquid having layers flowing past one another with little or no mixing. One way to do this is to force liquid through individual, parallel channels as it progresses towards a sharply-defined exit nozzle. While [Jesse] found no reference designs of laminar flow nozzles for air assists, there were definitely resources on making laminar flow nozzles for water. It turns out that interest in such a nozzle exists mainly as a means of modifying Lonnie Johnson’s brilliant invention, the Super Soaker.

Working from such a design, [Jesse] created a custom nozzle to help promote laminar flow. Sadly, a laser cutter head carries design constraints that make some compromises unavoidable; one is limited space, and another is the need to keep the laser’s path unobstructed. Still, after 3D printing it in rigid heat-resistant resin, [Jesse] found a dramatic improvement in the feel of the air exiting the nozzle. Some test cuts confirmed a difference in performance, which results in a noticeably cleaner kerf without scorching around the edges.

One of the things [Nervous System] does is make their own custom puzzles, so any improvement to laser cutting helps reliability and quality. When production is involved, just about everything matters; a lesson [Nervous System] shared when they discussed making the best plywood for creating their puzzles.

Big Nerf Bazooka Packs A Wallop

November 20, 2020 by Lewin Day 4 Comments

Nerf blasters are a fun toy, often confiscated from children once they hit one too many precious ornaments around the home in the midst of battle. [Ivan Miranda] is bigger than most children however, and set about building a much larger blaster.

The bazooka-like design uses a several meters of 160mm PVC pipe, firing “darts” constructed out of foam yoga rollers and buffing pads. The build uses a littany of 3D printed components in its construction, both as part of the firing mechanism and as jigs to help machine the pipe. A large plunger is used to propel the darts, which is pulled back against the tension of thick rubber tubes before being released by the trigger mechanism.

It’s an intimidating device, to be sure. However, we suspect its short range, huge size, and slow reload time should stop it from breaking the meta-game at your local Nerf battles. That said, we still wouldn’t want to take a shot from this bad boy to the head. Hackers do love a good Nerf build, and they’re particularly popular in sentry applications. Video after the break.

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3D Printable Cloth Takes Advantage Of Defects

November 20, 2020 by Al Williams 24 Comments

Normally, a 3D printer that under extrudes is a bad thing. However, MIT has figured out a way to deliberately mix full extrusions with under extruded layers to print structures that behave more like cloth than normal 3D printed items. The mesh-like structure apparently doesn’t require any modification to a normal 3D printer, just different software to create special code sequences to create the material.

Called DefeXtiles, [Jack Forman] is producing sheets and complex structures that appear woven. The process is known as “blob-stretch” because of the way the plastic makes blobs connected by fine filaments of plastic.

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