Comparing Ways To Add Threads To Your 3D Prints

January 11, 2025 by 33 Comments

Adding threads to your 3D prints is a life-changing feature, but obviously there are a lot of trade-offs and considerations when deciding on how to go about this exactly. Between self-tapping screws, printed threads, heat inserts and a dozen other options it can be tough to decide what to go with. In a recent video [Thomas Sanladerer] runs through a few of these options, including some less common ones, and what he personally thinks of them.

Confounding factors are also whether you’re printing on an FDM or resin printer, what size thread you’re targeting and how often the screw or bolt will be removed. The metal heat inserts are generally a good option for durability, but when you have big bolts you get a few other metal-based options too, including thread repair inserts and prong nuts. Tapping threads into a print can also be an option, but takes a fair bit of patience.

Slotted nuts can be an idea if you don’t mind carving a space into your model, and the comments dove on embedding nuts in the print by pausing during printing. Ultimately [Thomas] really likes to use a type of self-forming threads with just three protruding sections into the hole that the bolt taps into, which reduces the stress on the part and works well enough for parts that only have to be screwed down once or twice.

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Embedding Lenticular Lenses Into 3D Prints

January 11, 2025 by 11 Comments

A research project shows that it’s possible to create complex single-piece lenticular objects, or objects that have lenticular lenses built directly into them. The result is a thing whose appearance depends on the viewer’s viewpoint. The object in the image above, for example, is the same object from five different angles.

What’s really neat is that these colorful things have been 3D printed as single objects, no separate lenses or assembly required. Sure, it requires equipment that not just everyone has on their workbench, but we think a clever hacker could put the underlying principles to work all the same.

This lampshade (which was 3D printed as a single object) changes color and displays Good Day or Good Night depending on viewing angle.

The effect is essentially the same as what is sometimes seen in children’s toys and novelties — where a perceived image changes depending on the viewing angle. This principle has been used with a lenticular lens sheet to create a clever lenticular clock, but there’s no need to be limited by what lenses are available off the shelf. We’ve seen a custom 3D printed lenticular lens slapped onto a mobile device to create a 3D screen effect.

Coming back to the research, the objects researchers created go beyond what we’ve seen before in two important ways. First is in using software to aid in designing the object and it’s viewpoints (the plugin for Rhino 3D is available on GitHub), and the second is the scale of the effect. Each lens can be thought of as a pixel whose color depends on the viewing angle, and by 3D printing the lenses, one can fit quite a lot of them onto a surface with a high degree of accuracy.

To make these objects researchers used PolyJet 3D printing, which is essentially UV-cured resin combined with inkjet technology, and can create multi-color objects in a single pass. The lenses are printed clear with a gloss finish, the colors are embedded, and a final hit of sprayed varnish helps with light transmission. It sure beats placing hundreds of little lenses by hand.

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Tactility; The ESP32 Gets Another OS

January 11, 2025 by 11 Comments

Doing the rounds this week is a new operating system for ESP32 microcontrollers, it’s called Tactility, and it comes from [Ken Van Hoeylandt]. It provides a basic operating system level with the ability to run apps from an SD card, and it has the choice of a headless version or an LVGL-based touch UI.

Supported devices so far are some Lillygo and M5Stack boards, with intriguingly, support in the works for the Cheap Yellow Display board that’s caught some attention recently. The term “ESP32” is now a wide one encompassing Tensilica and RISC-V cores and a range of capabilities, so time will tell how flexible it is for all branches of the family.

We find this OS to be interesting, both in its own right and because it joins at least two others trying to do the same thing. There’s [Sprite_TM]’s PocketSprite mini console, and the operating system used by the series of Netherlands hacker camp badges,  We’ll be trying to get a device running it, in order to give you a look at whether it’s suitable for your projects. If it runs well on the cheaper hardware, it could be a winner!

AA Battery Performances Tested, So Get The Most For Your Money

January 10, 2025 by 38 Comments

[Project Farm] has a video in which a wide variety of AA cells are analyzed and compared in terms of capacity, internal resistance, ability to deliver voltage under load, and ability to perform in sub-freezing temperatures. Alkaline, lithium, and even some mature rechargeable cells with a couple thousand cycles under their belt were all compared. There are a few interesting results that will can help you get the most from your money the next time you’re battery shopping.

The video embedded below demonstrates a set of tests that we recommend you check out, but the short version is that more expensive (non-rechargeable) lithium cells outperform their alkaline peers, especially when it comes to overall longevity, ability to perform under high-drain conditions, and low temperatures. Lithium cells also cost more, but they’re the right choice for some applications.

Some brands performed better and others worse, but outside of a couple stinkers most were more or less comparable. Price however, was not.

As for how different brands stack up against one another, many of them are more or less in the same ballpark when it comes to performance. Certainly there are better and worse performers, but outside of a couple of stinkers the rest measure up reasonably well. Another interesting finding was that among rechargeable cells that were all several years (and roughly 2,200 charge-discharge cycles) old, a good number of them still performed like new.

Probably the single most striking difference among the different cells is cost — and we’re not just talking about whether lithium versus alkaline AAs are more cost-effective in the long run. Some brands simply cost twice as much (or more!) than others with comparable performance. If you’re in a hurry, jump to [Project Farm] presenting the final ranked results at 19:45 in.

Relying on brand recognition may save you from buying complete junk, but it’s clearly not the most cost-effective way to go about buying batteries.  These findings are similar to an earlier effort at wide-scale battery testing which also determined that factoring in price-per-cell was too significant to ignore.

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The Engineer Behind Mine Detection

January 10, 2025 by 8 Comments

According to [Joanna Goodrich]  in IEEE Spectrum, prior to World War II, soldiers who wanted to find land mines, simply poked at the ground with pointed sticks or bayonets. As you might expect, this wasn’t very safe or reliable. In 1941, a Polish signals officer, [Józef Stanislaw Kosacki], escaped to Britain and created an effective portable mine detector.

[Kosaci] was an electrical engineer trained at the Warsaw University of Technology. He had worked as a manager for the Polish National Telecommunication Institute. In 1937, the government tasked him with developing a machine that could detect unexploded grenades and shells. The machine was never deployed.

When Germany invaded Poland in 1939, [Kosacki] returned to military service (he had done a year of compulsory service earlier). He was captured and kept in a prison camp in Hungary. But he managed to escape in late 1939 and joined the Polish Army Corps in Britain, teaching Morse code to soldiers.

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Springs And Things Make For A Unique Timepiece

January 10, 2025 by 10 Comments

You never know when inspiration is going to strike, and for [Ekaggrat Singh Kalsi], it struck while he was playing with one of his daughter’s hair ties. The result is a clock called “Bezicron” and it’s a fascinating study in mechanical ingenuity.

The hair ties in question are simple objects, just a loose polymer coil spring formed into a loop that can be wrapped around ponytails and the like. In Bezicron, though, each digit is formed by one of these loops fixed to the ends of five pairs of arms. Each pair moves horizontally thanks to a cam rotating between them, changing the spacing between them and moving the hair tie. This forms each loop into an approximation of each numeral, some a little more ragged than others but all quite readable. The cams move thanks to a geared stepper motor on the rightmost digit of the hours and minutes section of the clock, with a gear train carrying over to the left digit. In between is the colon, also made from springy things pulsing back and forth to indicate seconds. The video below shows the clock going through its serpentine motions.

For our money, the best part of this build is the cams. Coming up with the proper shape for those had to be incredibly tedious, although we suspect 3D printing and rapid iterative design were a big help here. Practice with cam design from his earlier Eptaora clock probably helped too.

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Bit-Banging The USB-PD Protocol

January 10, 2025 by 14 Comments

For one-off projects, adding a few integrated circuits to a PCB is not too big of a deal. The price of transistors is extremely low thanks to Moore and his laws, so we’re fairly free to throw chips around like peanuts. But for extremely space-constrained projects, huge production runs, or for engineering challenges, every bit of PCB real estate counts. [g3gg0] falls into the latter group, and this project aims to remove the dedicated USB-PD module from a lighting project and instead bit-bang the protocol with the ESP32 already on the board.

The modern USB power delivery (PD) protocol isn’t quite as simple as older USB ports that simply present a 5V source to whatever plugs itself into the port. But with the added complexity we get a lot more capability including different voltages and greater power handling capabilities. The first step with the PD protocol is to communicate with a power source, which requires a 1.2V 600kHz signal. Just generating the signal is challenging enough, but the data encoding for USB requires level changes to encode bits rather than voltage levels directly. With that handled, the program can then move on to encoding packets and sending them out over the bus.

After everything is said and done, [g3gg0] has a piece of software that lets the ESP32 request voltages from a power supply, sniff and log PD communication, and inject commands with vendor defined messages (VDM), all without needing to use something like a CH224K chip which would normally offload the USB-PD tasks. For anyone looking to save PCB space for whatever reason, this could be a valuable starting point. To see some more capabilities of the protocol, check out this USB-PD power supply that can deliver 2 kW.