PCB holders are great tools. Not only is the PCB Solder Fren from [PistonPin] a nice DIY design, it offers some insight into the parts design process with FreeCAD.
The PCB holder uses 3D-printed parts, M5 hardware, a length of 2020 aluminum extrusion, and one spring to create a handy and adjustable design that accommodates a variety of PCB sizes and shapes. If the ends of the extrusion are threaded, the end caps can be screwed in. Otherwise, a little glue ought to do the trick.
Want a little more insight into what making a part like this involves? [Jo Hinchliffe] at FreeCAD reached out to [PistonPin] for more detail and has a blog post explaining the workflow and steps involved in this part. As a bonus, STEP files and the FreeCAD project file are all included!
Not only is FreeCAD simple to use, but it’s also flexible enough to accommodate custom, niche extensions like a Rocketry workbench, so be sure to give it a look for your open-source CAD needs.
The main design challenge was creating a tread system that would allow for the required rotation. [James] designed in the ability for each link to rotate about 18 degrees, and ensured plenty of open space on the upper side of the drive train to accommodate a full 180 degree twist. It took a little fine-tuning and looks a bit trippy, but in the end works about as well as a regular tread system.
[James] shows off a good technique to keep in mind when constructing big assemblies like this tank. It takes a lot of time and material to print large pieces, and in such cases it’s especially important to minimize rework. [James] therefore designs smaller, separate pieces as interfaces to other parts. This way, if changes are needed down the line (for example, to adjust motor placement or change tension on parts), only a smaller interface piece needs to be redone instead of having to re-print a huge part.
The unit uses an Arduino Mega, two 24 V gearmotors to drive each tread independently, an RC radio receiver, and some beefy BTS7960 DC motor drivers to drive the motors.
[Ivan Miranda] is taking a very interesting approach to a marble clock. His design is a huge assembly that uses black and white marbles to create a (sort of) dot matrix display. It’s part kinetic art and part digital clock, all driven by marbles.
Here’s how it works: black and white marbles feed into a big elevator. This elevator lifts marbles to the top of the curved runs that make up the biggest part of the device. The horizontal area at the bottom is where the time is shown, with white and black marbles making up the numerical display. But how to make sure the white marbles and black marbles go in the right order?
The solution to that is simple. Marbles feed into the elevator in an unpredictable order. An array of sensors detects the color of each marble. Solenoids simply eject any marble that isn’t in the right place. For example, if the next marble for track n needs to be white, then simply kick out any black marbles in that position until there’s a white one. Simple, effective, and guarantees plenty of mesmerizing moving parts.
Of course, this means that marble ejection and marble color sensing need to be utterly reliable, and [Ivan] ran into problems with both. Marble ejection took some careful component testing and selection to get the right solenoids. Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots.
You can watch the clock in action in the video embedded below just under the page break. We recommend giving it a look, because [Ivan] does a great job of showing all of the little challenges that reared their heads, and how he addressed them. There are still a few things to address, but he expects to have those licked by the next video. In the meantime, [Ivan] asks that if anyone knows a source for high quality glass marbles in bulk, please let him know. Low quality ones vary in size and tend to get stuck.
Some things are small and fragile enough that they cannot be held or touched by even the steadiest of hands. Such cases call for a micromanipulator, and [BYU CMR]’s DIY micromanipulator design can be 3D printed and assembled with the help of some common hardware, and a little CA glue.
You may recall an ultra-tiny Nerf-like blaster recently; clearly such a tiny mechanical device cannot be handled directly, yet needed to be loaded and have its trigger pressed. A micromanipulator is exactly the tool for such a job. This design is in fact the very same one used to move and manipulate that tiny blaster at a microscopic level.
The design doesn’t include any end effectors — those depend on one’s application — but there is a mount point for them and the manipulator can effectively move it in X, Y, and Z axes by turning three different knobs. In addition, because the structural parts can be 3D printed and the hardware is just some common nuts and screws, it’s remarkably economical which is always a welcome thing for a workshop.
[Ric Real] is entering the 2023 Hackaday Prize with the Gen5X, a generatively designed 3D printed five-axis 3D printer. The concept is not a new one, with the type of construction being seen a few times here and there. In addition to the usual three directions of motion, we’re familiar with, with the cartesian bot design, these types of machines add an additional two rotation axes, one which can swing the build platform front and back around the X-axis, and a second that provides rotation around the Z-axis. These combined motions give rise to some very interesting capabilities, outside of our familiar 3D printing design constraints.
As for the generative side of things, this is a largely theoretical idea. Essentially the concept is that the machine’s design can be iteratively updated and optimised for performance to fit into the constraints of available hardware such as motors and other ‘vitamins’ needed to create the next generation of machines. The design files should be parameterised enough such that this optimisation process can be automated, potentially via input from AI, but we suspect we’re a way off from that yet. Whether this project as yet satisfies any of these lofty goals remains to be seen, but do keep an eye on it if you’re so inclined. There is a Fusion 360 project here to dig into, but if you’re not interested in the research side of the project, but just want to build a 5-axis machine to play with, then you can find the project source on the GitHub Page.
3D printed materials have come a long way in the last decade or so as printers have become more and more mainstream. Printers can use all kinds of different plastics with varying physical characteristics, and there are even printers now for other materials like concrete and metal. But even staying within the realm of the plastic printer can do a lot of jobs you might not expect. [Camden Bowen] recently 3D printed a single-piston engine which nearly worked, and is back with some improvements to it thanks to a small carburetor.
The carburetor itself isn’t 3D printed (although not from lack of trying) — it’s on loan from a weed eater, and is helping to solve a problem with the fuel-air mixture of his original design. Switching from butane to a liquid fuel also solved some problems as well, and using starter fluid also helped to kick off the ignition. Although it ran for a short period of time over several starts, the valve train suffered some damage with the exhaust valves melting in place to the head. This is actually a problem common to any internal combustion engine like this, especially if the fuel-air mixture is too lean, there’s incomplete combustion, the valves aren’t adjusted properly, or any number of other problems. In this case it seems to have been caused by improper engine timing.
It’s actually noteworthy though that the intake valves weren’t burned, meaning that if the engine can be tuned to allow for complete combustion before the exhaust gasses leave the combustion chamber, the plastic 3D printed head and valve train will likely survive much longer operational periods. We’ll certainly look forward to the next iteration of this engine build to see if that’s the case. If 3D printed piston engines aren’t your speed, though, take a look at this jet engine which uses a 3D printed compressor.
Sometimes we have a new part or piece of tech that we want to use, and it feels like a solution looking for a problem. Upon first encountering NFC Tags, [nalanj] was looking for an application and thought they might make a great update to old-fashioned plant markers in a garden. Those are usually small and, being outside 24/7, the elements tend to wear away at what little information they hold.
[nalanj] used a freeform data structuring service called Cardinal to set up text information fields for each plant and even photos. Once a template has been created, every entry gets a unique URL that’s perfect for writing to an NFC tag. See the blog post on Cardinal’s site for the whole process, the thought behind the physical design of the NFC tag holder, and a great application of a pause in the 3D print to encapsulate the tags.
NFC tags are super hackable, though, so you don’t have to limit yourself to lookups in a plant database. Heck, you could throw away your door keys.