Review: Battery Spot Welders, Why You Should Buy A Proper Spot Welder

Making battery packs is a common pursuit in our community, involving spot-welding nickel strips to the terminals on individual cells. Many a pack has been made in this way, using reclaimed 18650 cells taken from discarded laptops. Commercial battery spot welders do a good job but have a huge inrush current and aren’t cheap, so it’s not uncommon to see improvised solutions such as rewound transformers taken out of microwave ovens. There’s another possibility though, in the form of cheap modules that promise the same results using a battery pack as a power supply.

With a love of putting the cheaper end of the global electronic marketplace through its paces for the entertainment of Hackaday readers I couldn’t resist, so I parted with £15 (about $20), for a “Mini Spot Welder”, and sat down to wait for the mailman to bring me the usual anonymous grey package.

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Modular Box Design Eases Silicone Mold-Making

Resin casting is a fantastic way to produce highly detailed parts in a wide variety of colors and properties, and while the process isn’t complicated, it does require a certain amount of care and setup. Most molds are made by putting a part into a custom-made disposable box and pouring silicone over it, but [Foaly] was finding the process of making and re-making those boxes a bit less optimized than it could be. That led to this design for a re-usable, modular, adjustable mold box that makes the workflow for small parts considerably more efficient.

The walls of the adjustable box are four identical 3D-printed parts with captive magnets, and the base of the box is a piece of laser-cut steel sheet upon which the magnetic walls attach. The positioning and polarity of the magnets are such that the box can be assembled in a variety of sizes, and multiple walls can be stacked to make a taller mold. To aid cleanup and help prevent contamination that might interfere with curing, the inner surfaces of each piece are coated in Kapton tape.

The result is a modular box that can be used and re-used, and doesn’t slow down the process of creating and iterating on mold designs. The system as designed is intended for small parts, but [Foaly] feels there is (probably) no reason it can’t be scaled up to some degree. Interested? The design files are available from the project’s GitHub repository, and if you need to brush up a bit on how resin casting works, you can read all about it here.

An Automatic Shop Vac Dust Extractor

Finding cheap or even free tools in the second-hand adverts is probably a common pursuit among Hackaday readers. Thus many of you will like [DuctTape Mechanic], have a row of old woodworking bench tools. The experience we share with him is a lack of dust extraction, which makes his adaption of a second-hand shop vac as an automatic dust extractor for his chop saw worth a watch. Take a look, we’ve put the video below the break!

The system hooks up a relay coil to the saw’s on/off switch, which controls the vacuum’s power. It’s thus not the most novel of hacks, but there are a few things to be aware of along the way and who among us doesn’t like watching a bit of gentle progress on a workshop project? The 120V current taken by both vacuum and saw sound excessive to those of us used to countries with 230V electricity, but the relay is chosen to easily serve that load. What’s nice about the automatic system is that being at the bench is not accompanied by the constant deafening noise of the shop vac, and save for when the saw is in use the bench is both dust-free and mercifully quiet.

If you happen to have a solid state relay in your parts bin, here’s another way to achieve a similar result.

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Your 1958 Punch Card Machine Tested Tubes

We think of punched cards as old-fashioned, but still squarely part of the computer age. Turns out, cards were in use way before they got conscripted by computers. Jacquard looms are one famous example. The U.S. Census famously used punched cards for tabulating the census without anything we’d consider a computer. But in the 1950s, you might have had a punched card machine on your electronics workbench. The Hickok Cardmatic was a tube tester with a difference.

About Tube Testers

While you, as a Hackaday reader, might tear into a busted TV at your house and try to fix it, most people today will either scrap a bad set or pay someone to fix it. That’s fine today. TVs are cheap and rarely break, anyway. But this hasn’t always been the case.

In the “good old days” your expensive TV broke down all the time. Most of the parts were reliable, but the tubes would wear out. If you were the kind of person who would change your own oil, you’d probably look to see if you could spot a burned out tube and try replacing it. If you couldn’t spot it, you’d pull all the tubes out. If you were lucky, there was a diagram glued inside the cover that showed where they all went back. Then you took them to the drugstore.

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Survey Of Simple Logic Simulators

A few months ago, a tweet by [Ken Shirriff] asking about simple digital simulators caught my attention. The topic came up again in May when a repair video by [CuriousMarc] featured one such simulator called Logisim-evolution. It made me want to take a fresh look on what’s out there and which features set the different simulators apart.

So today, let’s take a quick survey of a few such simulators that I found. I’m focusing on plain logic simulators, analyzing ones and zeros using Boolean logic. They are not doing SPICE-like analog analysis of transistor logic gates, but they’re still quite handy for proofing out designs.

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Old DSLR Lens Becomes Useful Soldering Magnifier

Soldering tiny stuff is hard, if not impossible, without some optical assistance. [Ad_w00000] was having just this problem, so built himself a soldering magnifier to help.

The magnifier uses a variety of components [Ad_w00000] had lying around. For the optical side of things, an old Canon DSLR zoom lens was pressed into service as the main magnifying element. The lens was then fitted with an old laptop webcam, which was glued into an old lens extender to avoid modifying the main lens itself. The webcam is hooked up to an Asus Tinkerboard fitted with a touchscreen display to show the images. The whole lens assembly is then fitted onto an old TV stand to enable it to sit far enough above the work surface to focus properly.

The build is a great example of building something useful out of whatever you have on hand. Sometimes, that’s cheaper and quicker than spending money and waiting for something to ship. It also has the bonus that you’ll learn useful skills along the way.

We’ve seen other great soldering hacks recently, too, like this gimbal to help steady hand tremors. If you’ve got your own coming together, be sure to let us know!

Soldering Iron Plus Camera Gimbal Helps Cancel Out Hacker’s Hand Tremors

Soldering requires steady hands, so when [Jonathan Gleich] sadly developed a condition called an essential tremor affecting his hands, soldering became much more difficult. But one day, while [Jonathan] was chatting with a friend, they were visited by the Good Ideas Fairy and in true hacker fashion, he ended up repurposing a handheld camera stabilizing gimbal to hold a soldering iron instead of a camera or smartphone. Now instead of the gimbal cancelling out hand movements to keep a camera steady, it instead helps keep a soldering iron steady.

While the inner workings of the cheap gimbal unit didn’t need modification, there were a couple of things that needed work before the project came together. The first was to set up a way to quickly and easily connect and disconnect the soldering iron from the gimbal. Thanks to a dovetail-like connector, the iron can be safely stored in its regular holster and only attached when needed.

The other modification is more subtle. The stabilizer motors expect to be managing something like a smartphone, but a soldering iron is both lighter and differently balanced. That meant that the system worked, but not as well as it needed to. After using some small lead weights to tweak the mass and center of gravity of the soldering iron — making it feel and move a bit more like an iPhone, as far as the gimbal was concerned — results were improved.

The soldering iron stabilizer works well enough for now, but we don’t doubt that [Jonathan] already has further tweaks in mind. This is a wonderful repurposing of a consumer device into an assistive aid, so watch it in action in the short video embedded below.

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