Layer Line Removal Putty Reviewed

[Teaching Tech] is not alone in hating layer lines in 3D prints and also hates sanding. He recently tried Incredafill putty, a UV-curable putty that you can use to cover up lines in prints. Once covered and cured, you sand the putty smooth. You can see what he thought of the product in the video below.

As many people suggested in the video comments, you can pull the same trick with UV resin thickened with some other substance. We’ve even covered using diluted resin to get a similar effect. The putty has more of the appearance of hair cream or some kind of ointment, so it was easy to spread around with a gloved finger. A brush also worked. UV curing was done by a small flashlight or the handy sun. However, you’ll see later that he used a UV curing station and that works well if you have one.

Of course, even after applying the putty, you still have to sand. We are assuming the sanding is easier than trying to sand the actual layer lines smooth. On the other hand, the resin dust is probably pretty toxic, so there is a trade-off involved.

The results did look good. Of course, since there was still sanding involved, how good it looks will depend on your sanding tools, your technique, and — perhaps most importantly — your patience. Sanding can do a lot for 3D prints. We might not trust it completely with resin dust, but you could get rid of at least some of the dust with a downdraft table.

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Hackaday Podcast 158: Phased Array Physics, CRTs Two Ways, A Micro Microcontroller, And A Surgically Implanted Red Herring

Join Editor-in-Chief Elliot Williams and Staff Writer Dan Maloney as they take a look at the week’s top stories, taken straight off the pages of Hackaday. What happens when you stuff modern parts into a 90’s novelty PC case? Nothing good, but everything awesome! Is there any way to prevent PCB soil moisture sensors from being destroyed by, you know, soil moisture? How small is too small for a microcontroller, and who needs documentation anyway? We also cast a jaundiced eye — err, ear — at an electronic cheating scandal, and if you’ve ever wondered how phased arrays and beam steering work, gazing into a pan of water might just answer your questions. We also share all our soldering war stories, and hey — what’s with all these CRT projects anyway?

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct Download (52 MB, but sounds like at least 58 MB!)

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Ballpoint Typewriters

So you want to minimize finger movement when you type, but don’t have three grand to drop on an old DataHand, or enough time to build the open-source lalboard? Check out these two concept keebs from [SouthPawEngineer], which only look like chord boards.

Every key on the home row is a five-way switch — like a D-pad with straight down input. [SouthPawEngineer] has them set up so that each one covers a QWERTY column. So like, for the left pinky switch, up is Q, right is A, down is Z, and left is 1. Technically, the split has 58 keys, and the uni has 56.

Both of these keebs use KB2040 boards, which are Adafruit’s answer to the keyboard-building craze of these roaring 2020s. These little boards are of course easy to program with CircuitPython, which supports KMK, an offshoot of the popular QMK. Thanks for the tip, [foamyguy]!

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Haptic Feedback “Rifle” Lets You Take Aim In VR

There was a time when virtual reality seemed like it would remain in the realm of science fiction at least for the foreseeable future. Then we were blessed with products like the Power Glove and Virtual Boy which seemed to make it more of a reality, if not a clunky and limited one. Now, though, virtual reality is taking more of a center stage as the technology for it improves and more and more games are released. We can see no greater proof of this than the fact that some gamers are building their own custom controllers to interact with the virtual world in more meaningful ways, like this game controller specifically built for first-person shooter games.

The controller is based on an airsoft gun but completely lacks the ability to fire a projectile, instead using the gun as a base for building the controller. In fact, the gun’s operation is effectively reversed in order to immerse the player into the game by using haptic feedback provided by pressurized air. The air is pumped in to what would be the front of the barrel and is discharged through the receiver when a trigger pull is detected in order to generate a recoil effect. The controller includes plenty of other features as well, including the ability to reload ammunition, change the firing mode, and track motion thanks to its pair of integrated Oculus controllers.

All of the parts for this controller are either 3D printed or readily available off-the-shelf, making this an ideal platform for customization and improvement. There’s also a demo game available from Unity which allows for a pretty easy setup for testing. While the controller looks like an excellent way to enjoy an FPS virtual reality experience, if you’re looking for a more general-purpose controller we are also starting to see a lot of development on that end as well.

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DIY bagpipe made from a latex glove and some straws.

Ring In The New Year With DIY Bagpipes

Remember early on in the pandemic when people would don protection just short of a full hazmat suit to go out, and wore rubber gloves to the grocery store? Was that just us? The point is, we are surely not alone in having an excess of latex gloves left over, and pitifully few uses for them aside from the usual — gross jobs around the house, and making hand-shaped ice cubes.

Circular breathing, explained.Well, here’s something a little more fun: DIY bagpipes. No matter how you feel about the sounds they produce, the way that bagpipes work is pretty interesting. In the video embedded after the break, [Charlie Engelman] shows us how they work and compares them to saxophonist Kenny G’s little jazz mouth.

See, Mr. G can circular breathe, which means he can hold a note for as long as he wants. Basically, he is able to keep a reserve of air in his mouth for playing the thing, while at the same time inhaling new air.

If we bring this back around to bagpipes, the bladder is akin to Kenny G’s mouth. It always contains air, so it perpetually releases air through the sound pipes that stick up. In the case of the glove pipe, the glove is the bladder, and the pipes are made of drinking straws. Check it out after the break — we think the sound is far more tolerable than real bagpipes.

We’ve seen bagpipes made from common household items before (if you consider a couple of plastic recorders to be common household items), and we’ve also seen real bagpipes go electromechanical.

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Twin jet engines mounted on tank treads

Big Wind Is The Meanest Firefighting Tank You Ever Saw

As the Iraqi army retreated at the end of the first Gulf War, they took the term “scorched Earth policy” quite literally. Kuwaiti oil wells were set alight en masse, creating towering infernos that blackened the sky.

As it turns out, extinguishing a burning oil well is no easy feat. In the face of this environmental disaster, however, a firefighting team from Hungary made a name for themselves out on the desert sands, astride a jet-engined tank named Big Wind.

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accelerometer, oled, and PocketBeagle create a gesture-controlled calculator

The Calculator Charm: Calculatorium Leviosa!

Have you ever tried waving your hand around like a magic wand and summoning a calculator? We would guess not since you’d probably look a little silly doing so. That is unless you had [Andrei’s] cool gesture-controlled calculator. [Andrei] thought it would be helpful to use a calculator in his research lab without having to take his gloves off and the results are pretty cool.

His hardware consists of a PocketBeagle, an OLED, and an MPU6050 inertial measurement unit for capturing his hand motions using an accelerometer and gyroscope. The hardware is pretty straightforward, so the beauty of this project lies in its machine learning implementation.

[Andrei] first captured a few example datasets to train his algorithm by recreating the hand gestures for each number, 0-9, and recording the resulting accelerometer and gyroscope outputs. He processed the data first with a wavelet transform. The intent of the transform was two-fold. First, the transform allowed him to reduce the number of samples in his datasets while preserving the shape of the accelerometer and gyroscope signals, the key features in the machine learning classification. Secondly, he was able to increase the number of features for the classification since the wavelet transform resulted in both approximation and detailed coefficients which can both be fed into the algorithm.

Because he had a small dataset, he used the Stratified Shuffle Split technique instead of the test train split method which is generally more suited for larger datasets. The Stratified Shuffle Split ensured approximately the same number of train and test samples for each gesture. He was also very conscious of optimizing his model for running on a portable processing unit like the PocketBeagle. He spent some time optimizing the parameters of his algorithm and ultimately converted his model to a TensorFlowLite model using the built-in “TFLiteConverter” function within TensorFlow.

Finally, in true open-source fashion, all his code is available on GitHub, so feel free to give it a go yourself. Calculatorium Leviosa!

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