Dissolve Steel Drill Bits in Alum from the Grocery

Breaking a stud or a bolt is a pretty common shop catastrophe, but one for which a fair number of solutions exist. Drill it out, shoot in an extractor, or if you’re lucky, clamp on some Vise-Grips and hope for the best. But when a drill bit breaks off flush in a hole, there aren’t a lot of options, especially for a small bit. If the stars align, though, you may follow this video guide to dissolve the drill bit and save the part.

Looks like [Adam Prince] lucked out with his broken bit, which he was using to drill the hole for a pin in a small custom brass hinge. It turns out that a hot solution of alum (ammonium aluminum sulfate), which is available in the spice rack of your local supermarket, will dissolve the steel drill bit without reacting with the brass. Aluminum is said to be resistant to the alum as well, but if your busted bit is buried in steel, you’re out of luck with this shop tip.

We’re a bit disappointed that [Adam]’s video ends somewhat abruptly and before showing us the end result. But a little Googling around reveals that this chemical technique is fairly well-known among a group that would frequently break bits in brass – clockmakers. It remains to be seen how well it would work for larger drill bits, but the clocksmiths seem to have had success with their tiny drills and broaches.

As for the non-dissolved remains of the broken bit, why not try your hand at knife making?

Build Your Own Function Generator

[Scullcom] has posted the second part of his function generator build tutorial. [Scullcom] previously posted the first part of this build which covered the XR2206 monolithic function generator IC on which his design is based. In this part [Scullcom] covers the output stages and final assembly.

We’ve covered digital and analog function generator builds before. [Scullcom]’s design complements these well by providing a detailed description of the design he used, and has provided full schematics and code from the Arduino Nano used in this project. The design covers audio frequencies (~40Hz to 30KHz) with square, sine and triangle wave outputs. While the XR2206 can’t compete with modern DDS function generators, if you’re a hacker on a budget and looking for a fun project this may be just the thing for you. And even if you don’t decide to build the one, you might find [Scullcom]’s description of the output stage interesting.

Great project [Scullcom] and we look forward to your next build!

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Pimp My Geiger Counter

In case your blissfully unaware of the radiation levels in your own home and city, did you know you can buy Arduino compatible Geiger Counters? They aren’t even that expensive! But, like any Arduino compatible board –they need a bit of dressing up to look like the real deal. [Folkert van Heusden] shows us his design, complete with directional LEDs and a laser cut enclosure.

He bought his first Geiger counter module a few years ago from Sparkfun — they retail for about 150 bones so they aren’t exactly cheap. But then he found an equivalent one on Aliexpres for about a quarter the cost — what did he have to lose? Really, he just wanted a cheap one he could walk around with and maybe scare his coworkers.  Continue reading “Pimp My Geiger Counter”

Upgraded LiPo Lawnmower Now Has Plenty of Juice

Back in 2010, [Dave] took a stand. He gave up his dependence on gasoline for his lawn mower, and bought a CubCadet CC500 48V lead acid powered electric lawnmower. Within two years, the batteries had already kicked the bucket. Unwilling to let go, he replaced half of the batteries, but that wasn’t enough. It now took him two charging cycles to mow his lawn once

Enough was enough. He had to replace the whole set — but this time, with LiPo.

As an avid lover of drones, he’s been using LiPo batteries for other things for quite a while. He did some calculations and figured he would only need about 10,000mAh at 48V for a 40 minute run time, which would still be a pretty pricey upgrade. So instead he started with 2 x 22.2V 5,200mAh packs instead ($200). As it turned out, that was more than enough.

The circuitry in the CubCadet was pretty straight forward, so it was almost a drop in replacement, minus the need to use a different charger. He added in a switch to flip between charging and mowing modes to allow him to use the LiPo charger without damaging anything.

Now all he needs to do is give it an Internet connection or maybe make it remote-controlled…

Field Expedient Stick Welder from Cordless Tool Battery Packs

The self-proclaimed and actual “smartest idiot on YouTube” is back with another entry from the “don’t try this at home” file. [AvE] recently did a teardown of a new DeWalt cordless drill-driver, and after managing to get everything back together, he was challenged by a viewer to repurpose the 20V battery packs into an impromptu stick welder.

AvE_short[AvE] delivered – sort of. His first attempt was with the two battery packs in parallel for higher current, but he had trouble striking an arc with the 1/8″ rod he was using. A freeze-frame revealed an incredible 160A of short-circuit current and a welding rod approaching the point of turning into plasma. Switching to series mode, [AvE] was able to strike a reasonable arc and eventually lay down a single splattery tack weld, which honestly looks better than some of our MIG welds. Eventually his rig released the blue smoke, and the postmortem teardown of the defunct packs was both entertaining and educational.

While we can’t recommend destroying $100 worth of lithium-ion battery packs for a single tack weld, it’s interesting to see how much power you’re holding in the palm of your hand with one of these cordless drills. We saw a similar technique a few years back in a slightly more sophisticated build; sadly, the YouTube video in that post isn’t active anymore. But you can always stay tuned after the break for the original [AvE] DeWalt teardown, wherein blue smoke of a different nature is released.

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The Internet of Soldering Irons

The Internet of Things needs — well — things. Do you really need your paper shredder hooked up to the Internet? Maybe. But [Vegard Paulsen] put something on the network that every hacker can relate to: his soldering iron.

In typical hacker fashion, fixing a broken digital display on the soldering station turned into a development project that allows [Vegard] to monitor the temperature of his soldering iron on his phone. He found a handy source of power on the station’s PC board and connected a NodeMCU WiFi device (that uses the ubiquitous ESP8266 and an onboard Lua interpreter).

internet-of-soldering-irons-meterThe data pushes out to the Thingspeak server which handles pushing data out to the bigger network, and data representation (like the cool Google gauge in the picture). The best part: [Vegard] gets a phone notification when he accidentally leaves his soldering iron on. How perfect is that?

One unique challenge he faced was soldering the power wires to the soldering station. This could be a problem because the iron tip is grounded so making the joint while the iron was energized would probably blow a fuse (or worse). Luckily, [Vegard] thought ahead and devised a plan that apparently worked.

We’ve seen other examples of how easy NodeMCU and Thingspeak work to put the mundane on the Internet. It seems particularly appropriate to hack a soldering iron, though.

Frankensteined Cordless Drill Lives Again

With tools, especially cordless tools, you’re going to pay now or pay later. On one hand, you can spend a bunch of money up front and get a quality tool that will last a long time. The other option is purchasing a cheap cordless tool that won’t last long, having to replace it later and thus spending more money. With cheap cordless tools it is common for the battery to fail before the physical tool making that tool completely unusable. Sure, another battery could be purchased but sometimes they cost just as much as the tool and battery combo originally did. So what’s a cordless tool user to do?

[EngergySaver] had a set of DeWalt cordless tools with a bunch of working batteries. He also had a cheap drill where the battery had died. His bundle of tools included two flashlights, one of which the case physically broke in half, probably from a clumsy drop. Instead of tossing the broken flashlight pieces in the garbage, [EngergySaver] kept them around for a while. Then one day he had the idea of combining the base of the broken DeWalt flashlight with the top of the old battery-less drill. He had the parts so why not?

The battery pack was 18 volt and the cheap drill expected 16.8 volts. [EngergySaver] figured the voltages were close enough and decided not to worry about the difference during his hack. He started by disassembling both the drill and flashlight down to the bare plastic housings. He marked an appropriate place to splice the handles and made some cuts. After the wiring was spliced together and the tool casings reassembled, a piece of sheet metal was cut and bent around the handle at the joint between flashlight and drill. Hose clamps hold the sheet metal tight around the handles, keeping the new hybrid tool together. And although we’re not crazy about the sheet metal and hose clamp method, it seems to be working just fine. With a little work and ingenuity [EngergySaver] resurrected an old tool for our favorite price; $0.