Infill Injection Experiment Makes Stronger Parts

February 25, 2025 by 28 Comments

[JanTec Engineering] was fascinated by the idea of using a 3D printer’s hot end to inject voids and channels in the infill with molten plastic, leading to stronger prints without the need to insert hardware or anything else. Inspiration came from two similar ideas: z-pinning which creates hollow vertical channels that act as reinforcements when filled with molten plastic by the hot end, and VoxelFill (patented by AIM3D) which does the same, but with cavities that are not uniform for better strength in different directions. Craving details? You can read the paper on z-pinning, and watch VoxelFill in (simulated) action or browse the VoxelFill patent.

With a prominent disclaimer that his independent experiments are not a copy of VoxelFill nor are they performing or implying patent infringement, [JanTec] goes on to use a lot of custom G-code (and suffers many messy failures) to perform some experiments and share what he learned.

Using an airbrush nozzle as a nozzle extension gains about 4 mm of extra reach.

One big finding is that one can’t simply have an empty cylinder inside the print and expect to fill it all up in one go. Molten plastic begins to cool immediately after leaving a 3D printer’s nozzle, and won’t make it very far down a deep hole before it cools and hardens. One needs to fill a cavity periodically rather than all in one go. And it’s better to fill it from the bottom-up rather than from the top-down.

He got better performance by modifying his 3D printer’s hot end with an airbrush nozzle, which gave about 4 mm of extra length to work with. This extra long nozzle could reach down further into cavities, and fill them from the bottom-up for better results. Performing the infill injection at higher temperatures helped fill the cavities more fully, as well.

Another thing learned is that dumping a lot of molten plastic into a 3D print risks deforming the print because the injected infill brings a lot of heat with it. This can be mitigated by printing the object with more perimeters and a denser infill so that there’s more mass to deal with the added heat, but it’s still a bit of a trouble point.

[JanTec] put his testing hardware to use and found that parts with infill injection were noticeably more impact resistant than without. But when it came to stiffness, an infill injected part resisted bending only a little better than a part without, probably because the test part is very short and the filled cavities can’t really shine in that configuration.

These are just preliminary results, but got him thinking there are maybe there are possibilities with injecting materials other than the one being used to print the object itself. Would a part resist bending more if it were infill injected with carbon-fibre filament? We hope he does some follow-up experiments; we’d love to see the results.

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We’re Hiring: Come Join Us!

February 25, 2025 by 29 Comments

You wake up in the morning, and check Hackaday over breakfast. Then it’s off to work or school, where you’ve already had to explain the Jolly Wrencher to your shoulder-surfing colleagues. And then to a hackspace or back to your home lab, stopping by the skull-and-cross-wrenches while commuting, naturally. You don’t bleed red, but rather #F3BF10. It’s time we talked.

The Hackaday writing crew goes to great lengths to cover all that is interesting to engineers and enthusiasts. We find ourselves stretched a bit thin and it’s time to ask for help. Want to lend a hand while making some extra dough to plow back into your projects? We’re looking for contributors to write a few articles per week and keep the Hackaday flame burning.

Contributors are hired as private contractors and paid for each article. You should have the technical expertise to understand the projects you write about, and a passion for the wide range of topics we feature. You’ll have access to the Hackaday Tips Line, and we count on your judgement to help us find the juicy nuggets that you’d want to share with your hacker friends.

If you’re interested, please email our jobs line (jobs at hackaday dot com) and include:

  • One example article written in the voice of Hackaday. Include a banner image, between 150 and 300 words, the link to the project, and any in-links to related and relevant Hackaday features. We need to know that you can write.
  • Details about your background (education, employment, interests) that make you a valuable addition to the team. What do you like, and what do you do?
  • Links to your blog/project posts/etc. that have been published on the Internet, if any.

Questions? Don’t hesitate to ask below. Ladies and Gentlemen, start your applications!

Custom Frame Grabber Gets Vintage Kodak Digital Camera Back In The Game

February 25, 2025 by 6 Comments

What do you do with a four-megapixel monochrome digital camera from the 90s that needed a dedicated PC with a frame grabber card to do anything useful? Easy — you turn it into a point-and-shoot by building your own frame grabber.

At least that’s what [Frost Sheridan] did with a vintage Kodak MegaPlus 4.2i, a camera that was aimed at the industrial and scientific market at a time when everyone was still using film for snapshots. Making this workhorse ride again meant diving into the manual, luckily still available after all these years, and figuring out what pins on the 68 pin connector would be useful. [Frost] worked out the pins for serial commands plus the 10-bit parallel interface, although he settled for the eight most significant bits to make things simpler. A Teensy with some extra RAM and a serial interface chip takes care of sending commands to the camera and pulling pixels off the parallel interface, and a 128×160 LCD provides a much-needed viewfinder.

With a battery pack mounted the whole thing is reasonably portable, if a bit of a chore to use. It’s worth the effort, though; the picture quality is fantastic, with a wide dynamic range and plenty of contrast. Hats off to [Frost] for bringing this beauty back to life without making any permanent modifications to it.

Tech In Plain Sight: Magsafe, And How To Roll Your Own

February 25, 2025 by 8 Comments

Apple likes magnets. They started out with magnetic laptop chargers and then graduated to a system that magnetically holds the phone, charges it, and can facilitate communication between the phone and a charger or other device. Even if you are like me and have no Apple devices, you can retrofit other phones to use Magsafe accessories. In fact, with a little work, you can build your own devices. Regardless, the technology is a clever and simple hack, and we are just a little sorry we didn’t think of it.

Terms

Using a magnet to attach a phone isn’t a new idea. But, historically, the phone had either a metal back or an adhesive metal plate attached that would stick to the magnet. This wouldn’t necessarily help with charging, but was perfectly fine for holding the device. The problem is, it is hard to wirelessly charge the phone through the metal.

Magsafe can do several different things. Obviously, it can attach the phone magnetically. However, since it is a ring shape, you can still have a charging coil in the middle of the ring. Better still, the Magsafe system will align the phone and charger with a satisfying click when you put them together.

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BlackBerry Keyboard Makes This Handheld Pi Stand Out

February 25, 2025 by 14 Comments

In the decade or more since small inexpensive Linux-capable single board computers such as the Raspberry Pi came to the mainstream, many a hardware hacker has turned their attention to making a portable computer using one. With such a plethora of devices having been made one might think that the Pi handheld was a done deal, but every so often along comes a new one of such quality to re-ignite the genre. So it is with [Taylor Hay]’s BlackberryPi Handheld. As you might guess from the name, it uses a BlackBerry keyboard along with a square LCD screen to create a beautifully executed Pi handheld in an almost GameBoy-like form factor.

It starts with a beautifully designed and executed case that holds a Pi and a Pimoroni HyperPixel screen. Unexpectedly this is a full-size Pi, we think a Pi 4. The keyboard is a USB enhanced Blackberry module which also has the famous trackpad, and there’s a bezel on the front to protect the screen. The power meanwhile comes from three 18650 cells inside the back of the case, with a power bank PCB. The surprise here is how simple he’s made it by careful choice of modules, the usual rats-nest of wires is missing.

The files are available so you can make your own, and he’s actively encouraging people to remix and improve it. We like this project, a lot, and after you’ve seen the video below the break, we think you will too. Oddly, this isn’t the first time we’ve seen someone try this combination.

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PCB Dielectric Constant Measurements, Three Ways

February 25, 2025 by 6 Comments

FR4 is FR4, right? For a lot of PCB designs, the answer is yes — the particular characteristics of the substrate material don’t impact your design in any major way. But things get a little weird up in the microwave range, and having one of these easy methods to measure the dielectric properties of your PCB substrate can be pretty handy.

The RF reverse-engineering methods [Gregory F. Gusberti] are deceptively simple, even if they require some fancy test equipment. But if you’re designing circuits with features like microstrip filters where the permittivity of the substrate would matter, chances are pretty good you already have access to such gear. The first method uses a ring resonator, which is just a PCB with a circular microstrip of known circumference. Microstrip feedlines approach but don’t quite attach to the ring, leaving a tiny coupling gap. SMA connectors on the feedline connect the resonator to a microwave vector network analyzer in S21 mode. The resonant frequencies show up as peaks on the VNA, and can be used to calculate the effective permittivity of the substrate.

Method two is similar in that it measures in the frequency domain, but uses a pair of microstrip stubs of different lengths. The delta between the lengths is used to cancel out the effect of the SMA connectors, and the phase delay difference is used to calculate the effective permittivity. The last method is a time domain measurement using a single microstrip with a couple of wider areas. A fast pulse sent into this circuit will partially reflect off these impedance discontinuities; the time delay between the reflections is directly related to the propagation speed of the wave in the substrate, which allows you to calculate its effective permittivity.

One key takeaway for us is the concept of effective permittivity, which considers the whole environment of the stripline, including the air above the traces. We’d imagine that if there had been any resist or silkscreen near the traces it would change the permittivity, too, making measurements like these all the more important.

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To Test A (Smart) LED

February 24, 2025 by 14 Comments

Adding LEDs to a project used to be enough to make it cool. But these days, you need arrays of addressable multi-color LEDs, and that typically means WS2812B or something similar. The problem is that while it was pretty easy to test garden-variety LEDs, these devices can be a bit harder to troubleshoot. [Gokux] has the answer, as you can see in the video below.

Testing these was especially important to [Gokux] because they usually swipe the modules from other modules or LED strips. The little fixture sends the correct pulses to push the LED through several colors when you hold it down to the pads.

However, what if the LED is blinking but not totally right? How can you tell? Easy, there’s a reference LED that changes colors in sync with the device under test. So, if the LEDs match, you have a winner. If not… well, it’s time to desolder another donor LED.

This is one of those projects that you probably should have thought of, but also probably didn’t. While the tester here uses a Xiao microcontroller, any processor that can drive the LEDs would be easy to use. We’d be tempted to breadboard the tester, but you’d need a way to make contact with the LED. Maybe some foil tape would do the trick. Or pogo pins.

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