Kritik sah

That’s not what an NTC should be reading. (Credit: The Repair Forge, YouTube) It’s no real secret that battery packs for power tools aren’t the foremost when it comes to user serviceability, so if said battery pack suddenly stops charging outside of warranty, you generally just e-waste it. That’s what [The Repair Forge] could have done for the Makita battery pack in question, but instead it was opened up for a diagnosis and fix. Rather than the charger throwing up an error with this specific battery, it would flash its red LED and run its fan, but never actually start the charging process. Apparently the charger seems to think that the battery is either too hot or cold to be charged, which already gives a big hint as to what might be wrong. Using the open source PocketOBI tool it’s possible to query the battery, which showed that one of the internal thermistors reported the battery being at a chilly -30°C while the other a more reasonable 28°C. After p...

Gears are usually the biggest contributors to backlash in a mechanical system, but they’re far from the only culprits. Ball bearings are a less obvious source of imprecision, since any gaps between the balls and the races can lead to axial wobble. Precision mechanisms can eliminate this by pairing two ball bearings, holding the outer races fixed, and applying a preload force to the inner traces. [Chronova Engineering], however, has a different solution, for which he split a ball bearing in half . Besides taking up more room, thermal expansion also means that it’s difficult to apply a consistent preload force between two ball bearings. Instead, to make a self-contained preloaded bearing, [Chronova Engineering] first disassembled a single ball bearing. The most difficult part of this is taking apart the ball cage; the two parts of this are normally riveted together, but he managed to find a crimped cage and pry it apart. After taking the bearing completely apart, he cut the outer trace...

In the world of children’s toys there are many offerings which are meant to look like devices used by older kids or even adults, with the Fisher Price Laugh & Learn Lil’ Gamer toy bearing quite the resemblance to Nintendo’s iconic Game Boy. Although this factoid could be filed away as amusing trivia before passing said toy to a child for its requisite physical abuse by said child, a purported adult can still have a lot of fun with this toy by modding it into a real Game Boy, as [KOUZEX] recently did . Part of the challenge here is to not just treat it as an unconventional replacement shell for a genuine Game Boy, but to retain as much of the child toy’s look and feel as possible. This includes things like buttons and even the weird sliding blocks on the side. For the functional components a Game Boy Color with a busted screen was chosen as a donor, with the GBC mainboard fitting almost perfectly inside its new shell. Wires were then soldered to bridge Nint...

The formula for a Raspberry Pi camera is by now a straightforward one: take a Pi and camera module, add a display, buttons, and battery, and you’re done. This doesn’t mean that there’s no scope for more though, and [Irtaza2009] has one in the PiShot . It’s a few months old now but the repository is still being updated. The 3D printed case follows a compact camera form factor with the screen on the rear, and a cold shoe on top. Inside is a Pi Zero 2 W and a Camera Module 3, with an 18650 cell and battery management/power supply board. The buttons are tactile switches hooked up to GPIOs, and the screen is an ST7789 SPI display. For software there’s a Python script, which should do the job. We’ve not tested this one, but our experience is that slowness is the Achilles’ heel of Python based Pi cameras. We hope this one has managed to eke out some performance. An interesting upgrade to this device would be to use an HQ camera module, for a mirror-...

You’ve seen fiber-reinforced-plastic before, no doubt, but perhaps never quite like in this video by [Whitburn Studio]: it’s still got the usual resin, but instead of glass or carbon fibers, he’s using printed Japanese cotton to create strong, lightweight and good looking parts for the interior of his RV– specifically the countertops. The technique is very similar to the sort of moldless composite work Burt Rutan pioneered in aircraft use. The fiber-reinforced plastic is formed around a positive ‘buck’ that remains inside the final part, adding stiffness and some backing. Unlike Rutan’s designs, which used pure Styrofoam inside, [Whitburn] is using a sandwhich of two layers of thin ply (3.6 mm) with XPS foam in between. Adding plywood means you don’t need many layers of fiber– again, that’s a decorative cotton, here– to get a surface that won’t dent into the styrofoam when you drop a coffee cup on it. Indeed, wit...

A recent addition to mountain bikes is the dropper seat post. This invention is in the vein of office swivel chairs, allowing the seat height to be adjusted with a simple handlebar mounted lever. They are rather fascinating inventions ranging in complexity from simple mechanical systems, to electronic monstrosities actuated by Bluetooth. Inspired by the panoply of possibilities, [kane components] set forth to create such a home-built dropper post.  Inspired by woodworking bar clamps, [kane’s] design utilizing angled plates binding against a rail inside the dropper post. Two pairs of plates sitting at opposite angles resist opposite forces from either the rider sitting on the post, or the return spring. A simple cable actuated cam moves the plates to a nonbinding position when the lever is actuated, and springs return the plates to a binding rest-state. The return is handled by an air spring pressurized against a piston at the bottom of the shaft. Though 3D printing could be us...