Wire-frame image of gearbox, setup as a differential

Roller Gearbox Allows For New Angles In Robotics

May 22, 2025 by Ian Bos 18 Comments

DIY mechatronics always has some unique challenges when relying on simple tools. 3D printing enables some great abilities but high precision gearboxes are still a difficult problem for many. Answering this problem, [Sergei Mishin] has developed a very interesting gearbox solution based on a research paper looking into simple rollers instead of traditional gears. The unique attributes of the design come from the ability to have a compact angled gearbox similar to a bevel gearbox.

Multiple rollers rest on a simple shaft allowing each roller to have independent rotation. This is important because having a circular crown gear for angled transmission creates different rotation speeds. In [Sergei]’s testing, he found that his example gearbox could withstand 9 Nm with the actual adapter breaking before the gearbox showing decent strength.

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Picture of self landing drone satellite with orange and black body. Propellors are extended.

FPV Drone Takes Off From A Rocketing Start

May 15, 2025 by Ian Bos 24 Comments

Launching rockets into the sky can be a thrill, but why not make the fall just as interesting? That is exactly what [I Build Stuff] thought when attempting to build a self-landing payload. The idea is to release a can sized “satellite” from a rocket at an altitude upwards of 1 km, which will then fly back down to the launch point.

The device itself is a first-person view (FPV) drone running the popular Betaflight firmware. With arms that swing out with some of the smallest brushless motors you’ve ever seen (albeit not the smallest motor), the satellite is surprisingly capable. Unfortunately due to concerns over the legality of an autonomous payload, the drone is human controlled on the descent.

Using collaborated efforts, a successful launch was flown with the satellite making it to the ground unharmed, at least for the most part. While the device did show capabilities of being able to fly back, human error led to a manual recovery. Of course, this is far from the only rocketry hack we have seen here at Hackaday. If you are more into making the flight itself interesting, here is a record breaking one from USC students.

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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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Liquid Silicone 3D Printing Is No Joke

May 7, 2025 by Tyler August 45 Comments

They might call it Levity, but there’s nothing funny about Rapid Liquid Print’s new silicone 3D printer. It has to be seen to be believed, and luckily [3D Printing Nerd] gives us lots of beauty shots in this short video, embedded below.

Smooth, and *fast*. This bladder took 51 minutes according to the RLP website.

Printing a liquid, even a somewhat-viscous one like platinum-cure silicone, presents certain obvious challenges. The Levity solves them with buoyancy: the prints are deposited not onto a bed, but into a gel, meaning they are fully supported as the silicone cures. The fact that the liquid doesn’t cure instantly has a side benefit: the layers bleed into one another, which means this technique should (in theory) be stronger in all directions than FDM printing. We have no data to back that up, but what you can see for yourself that the layer-blending creates a very smooth appearance in the finished prints.

If you watch the video, it really looks like magic, the way prints appear in the gel. The gel is apparently a commercially-available hydrogel, which is good since the build volume looks to need ̶a̶b̶o̶u̶t̶ ̶5̶0̶0̶ ̶L̶ at least 125 L of the stuff. The two-part silicone is also industry-standard and off-the-shelf, though no doubt the exact ratios and are tweaked for purpose. There’s no magic, just a really neat technology.

If you want one, you can sign up for the waiting list at Rapid Liquid Print’s website, but be prepared to wait; units ship next year, and there’s already a list.

Alternatively, since there is no magic here, we’d love to see someone take it on themselves, the way once equally exotic SLS printers have entered the DIY world. There was a time when resin printers were new and exotic and hobbyists had to roll their own, too. None of this is to say we don’t respect the dickens out of the Rapid Liquid Print team and their achievement–it’s just that imitation is the sincerest form of flattery. Continue reading “Liquid Silicone 3D Printing Is No Joke” →

3D Print Your Own Injection Molds, Ejector Pins And All

May 5, 2025 by Lewin Day 20 Comments

3D printing is all well and good for prototyping, and it can even produce useful parts. If you want real strenght in plastics, though, or to produce a LOT of parts, you probably want to step up to injection molding. As it turns out, 3D printing can help in that regard, with injection molding company [APSX] has given us a look at how it printed injection molds for its APSX-PIM machine.

The concept is simple enough—additive manufacturing is great for producing parts with complex geometries, and injection molds fit very much under that banner. To demonstrate, [APSX] shows us a simple injection mold that it printed with a Formlabs Form3+ using Rigid 10K resin. The mold has good surface finish, which is crucial for injection molding nice parts. It’s also fitted with ejection pins for easy part removal after each shot of injection molded plastic. While it’s not able to hold up like a traditional metal injection mold, it’s better than you might think. [APSX] claims it got 500 automatic injection cycles out of the mold while producing real functional parts. The mold was used with the APSX-PIM injection molding machine squirting polypropylene at a cycle time of 65 seconds, producing a round part that appears to be some kind of lid or gear.

This looks great, but it’s worth noting it’s still not cheap to get into this sort of thing. On top of purchasing a Formlabs Form3+, you’ll also need the APSX-PIM V3, which currently retails for $13,500 or so. Still, if you regularly need to make 500 of something, this could be very desirable. You could get your parts quicker and stronger compared to running a farm of many 3D printers turning out the same parts.

We’ve seen similar projects along these lines before. The fact is that injections molds are complicated geometry to machine, so being able to 3D print them is highly desirable. Great minds and all that. Video after the break.

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3D Printing A Useful Fixturing Tool

April 24, 2025 by Lewin Day 14 Comments

When you start building lots of something, you’ll know the value of accurate fixturing. [Chris Borge] learned this the hard way on a recent mass-production project, and decided to solve the problem. How? With a custom fixturing tool! A 3D printed one, of course.

Chris’s build is simple enough. He created 3D-printed workplates covered in a grid of specially-shaped apertures, each of which can hold a single bolt. Plastic fixtures can then be slotted into the grid, and fastened in place with nuts that thread onto the bolts inserted in the base. [Chris] can 3D print all kinds of different plastic fixtures to mount on to the grid, so it’s an incredibly flexible system.

3D printing fixtures might not sound the stoutest way to go, but it’s perfectly cromulent for some tasks. Indeed, for [Chris]’s use case of laser cutting, the 3D printed fixtures are more than strong enough, since the forces involved are minimal. Furthermore, [Chris] aided the stability of the 3D-printed workplate by mounting it on a laser-cut wooden frame filled with concrete. How’s that for completeness?

We’ve seen some other great fixturing tools before, too. Video after the break.

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