If you want to make serious assemblies out of 3D printed parts, you’ll eventually need to deal with threading. The easiest way is to make a nut trap that you can either insert a standard nut into after printing or even during printing. However, there are limitations to this method. If you want a real threaded part you can print the thread, cut the thread with a tap or bolt, or use a threaded insert. [Stefan] ran some tests to see how each of those methods held up to real use. (YouTube, embedded below.) He used fifty test parts to generate data for comparison.
We like the threaded insert method where a brass insert is pushed into the plastic while hot. Special features in the insert cause the brass part to grab the plastic, making it difficult to pull the insert out or twist it within the hole. Another thing we liked was that the tests used holes printed in the horizontal and vertical plane. You can clearly see that the orientation does alter how the holes work and fail to work.
The Volkswagen Beetle, and yes the bus and the sexiest car ever made, are cars meant for the people. You can pull the engine out with a strong friend, and you can fix anything in an old Volkswagen. VW realized this, because in the 1950s and ’60s, they came up with plans for tools designed to tear apart an old VW, and these tools were meant to be manufactured in a local shop. That really turns that right to repair on its head, doesn’t it?
While working on his van, [Justin Miller] came across a reference to one of these tools meant to be made at home. The VW 681 is a seal puller, designed to be manufactured out of bar stock. It’s an old design, but now we have interesting tools like 3D printers and parametric CAD programs. Instead of making one of these DIY seal pullers with a grinder, [Justin] brought this tool from the space age into the modern age. He took the design, modelled it in OpenSCAD, and printed it out.
The VW reference book that lists this tool is Workshop Equipment for Local Manufacture, and for this seal puller, it gives perfectly dimensioned drawings that are easily modelled with a few lines of code. The only real trouble is filing down the pointy bit of the puller, but a bit of boolean operations fixed that problem. After 15 minutes of printing and a few hours finding the right documentation and writing fifteen lines of code, [justin] had a plastic VW 681 in his hands. Yes, it was probably a waste of time as a regular seal puller could have done the job, but it’s an excellent example of what can happen when manufacturers support their local repairman.
Combination locks! They’re great if you’re skilled at remembering arbitrary strings of numbers, and have a dramatic flair that’s made them a famous part of many a heist movie. They come in a wide variety of styles, and are vulnerable to a different set of attacks than the more typical pin-tumbler locks used on a household basis. If you fancy tinkering with a combination lock, why not 3D print one yourself?
It goes without saying that any lock you 3D print is going to have issues with strength. Such a lock should not be used to protect anything of real value, but it could be handy to prevent the kids getting at the Halloween candy you’re saving for October.
Regardless, 3D printing and assembling your own combination lock is a great way to learn about how they work. It’s a fun project that is also much easier than sourcing and disassembling the real thing. For a greater understanding of the underlying mechanism, this video should make the basic operation clear.
Last year, mathematician and professional optical illusionist [Kokichi Sugihara] came up with an arrow that only points one way. Technically, it’s ‘anomalous mirror symmetry’, but if you print this arrow and look at it juuuussst right, it appears this arrow only points one way.
[Ali] had the idea to turn this arrow illusion into something motorized, and for that he turned to 3D printing. The models for the illusion arrows were already available, but there had to be a way to turn a single arrow into an art installation. For that, you just need a few 9g servos. [Ali] slightly modified his servos so they would turn a full 180 degrees, and designed a magnetic mount to allow easy swap-out of these arrows.
The servos are attached to a 3D printed frame with heat-staked threaded inserts, and driven by a Pololu servo driver. The effect is great, with multiple arrows twisting and turning but still only appearing to point to the right. [Ali] put together two videos of this arrow illusion, one that’s effectively a build guide, and of course all the STLs are available in a link in the description.
Inspiration runs on its own schedule: great ideas don’t always arrive in a timely manner. Such was the case with [Daren Schwenke]’s notion for creating a 3D-printed blooming rose for his valentine, a plan which came about on February 13. Inspired by [Jiří Praus]’s animated wireframe tulip, [Daren] figured he could make a rose from clear printed petals colored by RGB LEDs. 24 hours seemed tight but sufficient, so he diligently set to work, but – after a valiant effort – finally had to extend the schedule. It’s now more than a month later, and tweaks to the design continue, but the result is nothing short of spectacular.
We first saw a discussion of the idea over on Hack Chat, and followed as it evolved into a project on hackaday.io. There, you can read the full details of the trials and tribulations that had to be endured to make this project happen. From a printer that wouldn’t boot, through testing PLA, TPU, and nylon filament, trying a number of different approaches for springs and hinges to operate the petals, and wiring the delicate DotStar LEDs with magnet wire, you can get a really good sense of the amount of experimentation it takes to complete a project like this. If you know anyone who still thinks 3D printing is as easy as clicking a button, send them over to read the logs on this project.
An early try at forming PLA petals
What finally materialized is a terrific combination of common hacker technologies. The petals are printed flat in nylon, then formed over a hot incandescent chandelier bulb. The stem and leaves are also printed, but the side stem has a piece of magnet wire embedded in the print as a capacitive touch sensor; when the leaf is touched, the rose blossom opens or closes. Magnet wire for the LEDs and a connecting rod for the mechanics run through the main stem to the base, where a 9g servo is responsible for controlling the bloom. The whole thing is controlled, naturally, with an Arduino. To move the project along a little more quickly, [Daren] enlisted the help of another Hack Chat denizen, [Morning.Star], who did an amazing job on the software without any access to the actual hardware.
Be sure to check out the video of the rose in action, after the break.
When you really start fine-tuning your 3D printer, you might start to notice that even the smallest things can have a noticeable impact on your prints. An open window can cause enough of a draft to make your print peel up from the bed, and the slightly askew diameter of that bargain basement filament can mess up your extrusion rate. It can be a deep rabbit hole to fall down if you’re not careful.
One element that’s often overlooked is the filament spool; if it’s not rotating smoothly, the drag it puts on both the extruder and movement of the print head can cause difficult to diagnose issues. For his custom built printer, [Marius Taciuc] developed a very clever printable gadget that helps the filament roll spin using nothing but the properties of the PLA itself. While the design might need a bit of tweaking to work on your own printer, the files he’s shared should get you most of the way there.
All you need to do is print out the hubs which fit your particular filament spools (naturally, they aren’t all a standard size), and snap them on. The four “claws” of the hub lightly contact a piece of 8 mm rod enough to support the spool while limiting the surface area as much as possible. The natural elasticity of PLA helps dampen the moment that would result if you just hung the hub-less spool on the rod.
The STL files [Marius] has provided for his low-friction hubs should work fine for anyone who’s interested in trying out his design, but you’ll need to come up with your own method of mounting the 8 mm rod in a convenient place. The arms he’s included are specifically designed for his customized Prusa Mendel, which is pretty far removed from contemporary desktop 3D printer design. Something to consider might be a piece of 8 mm rod suspended over the printer, with enough space that you could put a couple spools on for quick access to different colors or materials.
We often think of 3D printing as a way to create specific components in our builds, everything from some hard-to-find little sprocket to a custom enclosure. More and more of the projects that grace the pages of Hackaday utilize at least a few 3D printed parts, even if the overall build itself is not something we’d necessarily consider a “printed” project. It’s the natural progression of a technology which at one time was expensive and complex becoming increasingly available to the maker and hacker.
But occasionally we see 3D printing used not to create new devices, but recreate old ones. A perfect example is the almost entirely 3D printed telegraph system created by [Matt]. Projects like this help bring antiquated technology back to a modern audience, and can be an excellent educational tool. Showing someone a diagram of how the telegraph worked is one thing, but being able to run off a copy on your 3D printer and putting a working model in their hands is quite another.
[Matt] acknowledges that he’s hardly the first person to 3D print a telegraph key, but says that he’d never seen the complete system done before. The key is perhaps the component most people are familiar with from film and old images, but alone it’s really nothing more than a momentary switch. To actually put it to use, you need a telegraph sounder on the receiving end to “play” the messages.
The sounder is a somewhat more complex device than the key, and uses an electromagnet to pull down a lever and produce an audible clicking noise. In the most basic case, the coil is directly connected to the key, but in a modern twist [Matt] has added a MOSFET into the circuit so the electromagnet is triggered locally within the sounder. This prevents sparks from eroding the contacts in the key, and alleviates problems associated with current loss over long wire runs.
