3D Printing Uranium-Carbide Structures For Nuclear Applications

May 19, 2025 by Maya Posch 11 Comments

Fabrication of uranium-based components via DLP. (Zanini et al., Advanced Functional Materials, 2024)

Within the nuclear sciences, including fuel production and nuclear medicine (radiopharmaceuticals), often specific isotopes have to be produced as efficiently as possible, or allow for the formation of (gaseous) fission products and improved cooling without compromising the fuel. Here having the target material possess an optimized 3D shape to increase surface area and safely expel gases during nuclear fission can be hugely beneficial, but producing these shapes in an efficient way is complicated. Here using photopolymer-based stereolithography (SLA) as recently demonstrated by [Alice Zanini] et al. with a research article in Advanced Functional Materials provides an interesting new method to accomplish these goals.

In what is essentially the same as what a hobbyist resin-based SLA printer does, the photopolymer here is composed of uranyl ions as the photoactive component along with carbon precursors, creating solid uranium dicarbide (UC₂) structures upon exposure to UV light with subsequent sintering. Uranium-carbide is one of the alternatives being considered for today’s uranium ceramic fuels in fission reactors, with this method possibly providing a reasonable manufacturing method.

Uranium carbide is also used as one of the target materials in ISOL (isotope separation on-line) facilities like CERN’s ISOLDE, where having precise control over the molecular structure of the target could optimize isotope production. Ideally equivalent photocatalysts to uranyl can be found to create other optimized targets made of other isotopes as well, but as a demonstration of how SLA (DLP or otherwise) stands to transform the nuclear sciences and industries.

The frame of a delta 3D printer is shown. The toolhead of the 3D printer does not have a hotend installed, but instead has a frame with a circular hole in the middle.

A Toolchanging Delta 3D Printer

May 13, 2025 by Aaron Beckendorf 3 Comments

We’ve seen quite a few delta 3D printers, and a good number of toolchanging printers, but not many that combine both worlds. Fortunately, [Ben Wolpert]’s project fills that gap with a particularly elegant and precise delta toolchanger.

The hotend uses three steel spheres and triangular brackets to make a repeatable three-point contact with the toolhead frame, and three pairs of corresponding magnets hold it in place. The magnets aren’t in contact, and the three magnets on the toolhead are mounted in a rotating ring. A motorized pulley on the printer’s frame drives a cable which runs through a flexible guide and around the rotating ring.

The whole setup is very reminiscent of the Jubilee toolchanging system, except that in this case, the pulley rotates the ring of magnets rather than a mechanical lock. By rotating the ring of magnets about 60 degrees, the system can move the pairs of magnets far enough apart to remove the hotend without much force.

The rest of the toolchanging system is fairly straightforward: each tool’s parking area consists of two metal posts which slot through corresponding holes in the hotend’s frame, and the motherboard uses some RepRapFirmware macros to coordinate the tool changes. The only downside is that a cooling fan for the hotend still hadn’t been implemented, but a desk fan seemed to work well enough in [Ben]’s tests. The files for the necessary hardware and software customizations are all available on GitHub.

We’ve only seen a similar toolchanging system for a delta printer once before, but we have seen a great variety of toolchangers on the more common Cartesian systems. Don’t like the idea of changing extruders? We’ve also seen a multi-extruder printer that completely eliminates tool switching.

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Learn 15 Print-in-Place Mechanisms In 15 Minutes

May 11, 2025 by Dave Rowntree 4 Comments

3D printed in-place mechanisms and flexures, such as living hinges, are really neat when you can get them to print correctly. But how do you actually do that? YouTuber [Slant 3D] is here with a helpful video demonstrating the different kinds of springs and hinges (Video, embedded below) that can be printed reliably, and discusses some common pitfalls and areas to concentrate upon.

Living hinges are everywhere and have been used at least as long as humans have been around. The principle is simple enough; join two sections to move with a thinned section of material that, in small sections, is flexible enough to distort a few times without breaking off. The key section is “a few times”, as all materials will eventually fail due to overworking. However, if this thing is just a cheap plastic case around a low-cost product, that may not be a huge concern. The video shows a few ways to extend flexibility, such as spreading the bending load across multiple flexure elements to reduce the wear of individual parts, but that comes at the cost of compactness.

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Move Over, Lithophane: 3D Printed 3D Photos With Gaussian Splats

May 10, 2025 by Tyler August 24 Comments

If you had asked us yesterday “How do you 3D Print a Photo”, we would have said “well, that’s easy, do a lithophane”– but artist, hacker and man with a very relaxing voice [Wyatt Roy] has a much more impressive answer: Gaussian splats, rendered in resin.

Gaussian splats are a 3D scanning technique aimed at replicating a visual rather than geometry, like the mesh-based 3D-scanning we usually see on Hackaday. Using photogrammetry, a point cloud is generated with an associated 3D Gaussian function describing the colour at that point. Blend these together, and you can get some very impressive photorealistic 3D environments. Of course, printing a Gaussian smear of colour isn’t trivial, which is where the hacking comes in.

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Best Practices For FDM Printing

May 10, 2025 by Al Williams 38 Comments

If you’ve been designing parts for 3D printing, you probably have some tricks and standards for your designs. [Rahix] decided to write out a well-thought-out set of design rules for FDM prints, and we can all benefit.

One of the things we liked about the list is that it’s written in a way that explains everything. Every so often, there’s a box with a summarized rule for that topic. At the end, there’s a list of all the rules. The rules are also in categories, including part strength, tolerance, optimization, integration, machine elements, appearance, and vase mode.

For example, section two deals with tolerance and finish. So, rule R2.8 says, “Do not use circular holes for interference fits. Use hexagon or square holes instead.”

We also appreciate that [Rahix] touched on some of the counter-intuitive aspects of designing for FDM printing. For example, you might think adding voids in your part will reduce the filament and time required to print it, but in many cases it can have the opposite effect.

Some of these — maybe even most of these — won’t surprise you, but you still might take away a tidbit or two. But having it all down in a checklist and then the ability to scroll up and find the rationale for the rule is great.

Do you have any rules you’d add? Or change? Let us know. Meanwhile, we were eyeing our favorites about adding machine elements to prints.

Scan Your Caliper For Physical Part Copies

May 9, 2025 by Al Williams 60 Comments

We’ve certainly seen people take a photo of a part, bring it into CAD, and then scale it until some dimension on the screen is the same as a known dimension of the part. We like what [Scale Addition] shows in the video below. In addition to a picture of the part, he also takes a picture of a vernier caliper gripping the part. Now your scale is built into the picture, and you can edit out the caliper later.

He uses SketchUp, but this would work on any software that can import an image. Given the image with the correct scale, it is usually trivial to sketch over the image or even use an automatic tracing function. You still need some measurements, of course. The part in question has a vertical portion that doesn’t show up in a flat photograph. We’ve had good luck using a flatbed scanner before, and there’s no reason you couldn’t scan a part with a caliper for scale.

This is one case where a digital caliper probably isn’t as handy as an old-school one. But it would be possible to do the same trick with any measurement device. You could even take your picture on a grid of known dimensions. This would also allow you to check that the distances at the top and bottom are the same as the distances on the right and left.

Of course, you can get 3D scanners, but they have their own challenges.

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3D Printed TPU Bellows With PLA Interface Layers

May 8, 2025 by Maya Posch 22 Comments

Of all FDM filament types, flexible ones such as TPU invite a whole new way of thinking, as well as applications. Case in point the TPU-based bellows that the [Functional Part Friday] channel on YouTube recently demonstrated.

The idea is quite straightforward: you print TPU and PLA in alternating layers, making sure that the TPU is connected to its previous layer in an alternating fashion. After printing, you peel the PLA and TPU apart, remove the PLA layers and presto, you got yourself bellows.

There were some issues along the way, of course. Case in point the differences between TPU from different brands (Sainsmart, Sunlu) that caused some headaches, and most of all the incompatibility between the Bambu Lab AMS and TPU that led to incredibly brittle TPU prints. This required bypassing the feed mechanism in the AMS, which subsequently went down a rabbit hole of preventing the PTFE tube from getting sucked into the AMS. Being able to print TPU & PLA at the same time also requires a printer with two independent extruders like the Bambu Lab H2D used here, as both materials do not mix in any way. Great news for H2D and IDEX printer owners, of course.

As for practical applications for bellows, beyond printing your own 1900s-era camera, accordion or hand air bellows, you can also create lathe way covers and so on.

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