Two tools for placing magnets with ease, one for each polarity.

An Attractive Magnet Insertion Tool

Magnets are pretty nice little tools. [EmGi] has used them in many a cool 3D printed build with great success. But getting them where you want can be really tricky. More often than not, you end up with glue all over your fingers, or the magnets fly out of place, or they stick together when you don’t want them to.

Depositing an array of 64 magnets into a 3D print to stress test the magnet-depositing tool.Well, [EmGi] created a mighty fine magnet insertion tool that you can print for yourself. It’s finger-operated and uses a single embedded magnet to place magnets wherever they’re needed.

This thing went through several designs before [EmGi] ever printed it out. Originally, there were two magnets, but there was an issue where if the tool wasn’t lifted off perfectly, it would send the magnet flying.

But now it works great, and [EmGi] even deposited an array of 64 magnets without using glue to test it out before printing a second one to handle the other polarity. Check out the build/demo video after the break.

While you’re printing and placing magnets, why not make yourself a couple of magnetic switches? You can even make ’em for keyboards.

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Walking The Plank: Add-Ons For The Bus Pirate

The Bus Pirate multi-tool has held a place of honor in many a hardware hacker’s toolbox for years, and the latest generation of the gadget powered by the Raspberry Pi RP2040/RP2350 offers significantly enhanced capabilities over the original PIC versions. We took a look at the new Bus Pirate when it started shipping back in February, and while the firmware was still in the early stages back then, it was already clear that creator [Ian Lesnet] and his team had put together a compelling product.

Over the last several months, the Bus Pirate software has improved dramatically. New features have started showing off the hardware’s capabilities, and the user experience is far improved over where it was at release. Following the firmware development is a roller coaster ride, with [Ian] sometimes pushing out several updates a day. Luckily, like the Pi Pico itself, updating the new Bus Pirate only takes a second.

But as impressive and important as those software updates have been, that’s not what we’re talking about today. In this post, we’ll take a look at one of the most exciting aspects of the new Bus Pirate — the ability to easily develop add-on modules for it.

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Insides of a multimeter, improved with a custom backlight switch.

Backlight Switch For A Better Multimeter

Frustrated by his Aldi multimeter’s backlight turning off after just 15 seconds, [Steg Steg] took matters into his own hands. His solution? He added a manual toggle switch to control the backlight, allowing it to stay on as long as needed. He began by disassembling the multimeter—removing the outer bumper and a few screws—to access the backlight, labeled “BL.” He identified the voltage regulator outputting 2.8 V, desoldered the red wire, and extended it to install the switch.

On his first try, he successfully drilled a spot for the SPST switch. To fit the switch into the multimeter’s rubber bumper, he used a circular punch, although his second hole wasn’t as clean as the first. Despite this minor setback, the modification worked perfectly, giving him complete control over his multimeter’s backlight without the original 15-second timeout.

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Are You Using Your Calipers Wrong?

It used to be that calipers were not a common item to have in an electronics lab. However, smaller parts, the widespread use of 3D printers and machining tools, and — frankly — cheap imported calipers have made them as commonplace as an ordinary ruler in most shops. But are you using yours correctly? [James Gatlin] wasn’t and he wants to show you what he learned about using them correctly.

The video that you can see below covers digital and vernier calipers. You might think digital calipers are more accurate, in practice, they are surprisingly accurate, although the digital units are easier to read.

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Fighting The Scourge Of “Screwdriver Mange”

We’ve all got our favorite hand tools, and while the selection criteria are usually pretty subjective, it usually boils down to a combination of looks and feel. In our opinion, the king of both these categories when it comes to screwdrivers is those clear, hard acetate plastic handles, which are a joy to use — at least until the plastic starts to degrade and exude a characteristically funky aroma.

But perhaps we can change that if these experiments on screwdriver “mange” hold up. That’s [357magdad]’s unappealing but accurate description of the chemical changes that eventually occur in the strong, hard, crystal-clear handles of your favorite screwdrivers. The polymer used for these handles is cellulose acetate butyrate, or CAB, which is mostly the same cellulose acetate that replaced the more explode-y cellulose nitrate in things like pool balls and movie film, except with some of the acetate groups replaced with a little butyric acid. The polymer is fine at first, but add a little UV light and over time the outer layer of CAB decomposes into a white flaky cellulose residue while the butyric acid volatilizes, creating the characteristic odor of vomitus. Lovely.

In the video below, [357magdad] takes a look at different concoctions that all allegedly cure the mange. TL, DW; it was a dunk in household ammonia that performed the best, well ahead of other common agents like vinegar and bleach. The ammonia — or more precisely, ammonium hydroxide — works very quickly on the cellulose residue, dissolving it readily and leaving the handle mange-free and looking nearly new after some light scrubbing. None of the other agents came close, although acetone did manage to clear up the mange a bit, at the cost of softening the underlying CAB in a process that’s probably similar to acetone smoothing ABS prints.

As for the funky smell, well, the results were less encouraging. Nothing really got rid of the pukey smell, even a roll in baking soda. We suspect there won’t be much for that, since humans can detect it down to 10 parts per million. Consider it the price to pay for a nice-looking screwdriver that feels so good in your hand. Continue reading “Fighting The Scourge Of “Screwdriver Mange””

Handheld Oscilloscope Meter Reviewed

We live in a time where there’s virtually no excuse not to have some kind of oscilloscope. As [IMSAI Guy] shows in a recent video, for what you might expect to pay for a decent meter, you can now get one that includes a scope. There are several options out there but it is hard to know how much to spend to get the best possible product. The Zoyi ZT-702S that he looks at costs under $80. But is it worth it?

Scopes that connect to your PC are often very inexpensive. You can also find little toy scopes that use a microcontroller and a little LCD screen. Even though the specs on these are usually appalling, they will still let you visualize what’s happening in a circuit. Sure, you want an expensive bench scope with lots of channels sometimes, but often, you just need to see a signal in broad strokes. Having a scope and a meter together is very handy.

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Custom Pneumatic Cylinders Lock This Monitor Arm In Place

Few consumer-grade PCs are what you’d categorize as built to last. Most office-grade machines are as likely as not to give up the ghost after ingesting a few too many dust bunnies, and the average laptop can barely handle a few drops of latte and some muffin crumbs before croaking. Sticking a machine like that in the shop, especially a metal shop, is pretty much a death sentence.

And yet, computers are so useful in the shop that [Lucas] from “Cranktown City” built this neat industrial-strength monitor arm. His design will look familiar to anyone with a swing-arm mic or desk light, although his home-brew parallelogram arm is far sturdier thanks to the weight of the monitor and sheet-metal enclosure it supports. All that weight exceeded the ability of the springs [Lucas] had on hand, which led to the most interesting aspect of the build — a pair of pneumatic locks. These were turned from a scrap of aluminum rod and an old flange-head bolt; when air pressure is applied, the bolt is drawn into the cylinder, which locks the arm in place. To make it easy to unlock the arm, a pneumatic solenoid releases the pressure on the system at the touch of a button. The video below has a full explanation and demonstration.

While we love the idea, there are a few potential problems with the design. The first is that this isn’t a fail-safe design, since pressure is needed to keep the arm locked. That means if the air pressure drops the arm could unlock, letting gravity do a number on your nice monitor. Second is the more serious problem [Lucas] alluded to when he mentioned not wanting to be in the line of fire of those locks should something fail and the piston comes flying out under pressure. That could be fixed with a slight design change to retain the piston in the event of a catastrophic failure.

Problems aside, this was a great build, and we always love [Lucas]’ seat-of-the-pants engineering and his obvious gift for fabrication, of which his wall-mount plasma cutter is a perfect example.

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