Beats an Extension Cord

What does your benchtop power supply have that [Pete Marchetto]’s does not? Answer: an extension cord draped across the floor. How often have you said to yourself, “I just need to energize this doodad for a couple seconds,” then you start daisy chaining every battery in the junk drawer to reach the necessary voltage? It is not uncommon to see battery packs with a single voltage output, but [Pete] could not find an adjustable one, so he built his own and put it on Tindie.

Presumably, the internals are not going to surprise anyone: an 18650 battery, charging circuit, a voltage converter, display, adjustment knob, and a dedicated USB charging port. The complexity is not what intrigues us, it is the fact that we do not see more of them and still wind up taping nine-volt batteries together. [Editor’s note: we use one made from an old laptop battery.]

This should not replace your benchtop power supply, it does not have the bells and whistles, like current regulation, but a mobile source of arbitrary voltage does most of the job most of the time. And it’s what this build hasn’t got (a cord) that makes it most useful.

Universal Quick-Release Bar Clamps

The typical hacker can never say no to more tools. And when it comes to clamps, one just can’t have enough of them. From holding small PCB’s to clamping together large sheets of plywood, you need a variety of sizes and quantities. So it would be pretty neat if we could just 3D print them whenever needed. [Mgx3d] has done that by designing 3D printable bar clamp jaws with a quick release mechanism that can be used with standard T-slot aluminum extrusion. This allows you to create ad-hoc bar clamps of any size and length quickly.

The design consists of two pieces – the jaw and its quick release lever, and does not require any additional parts or fasteners for assembly. Both pieces can be easily 3D printed without supports. The quick release lever is a simple eccentric cam design which locks the jaw in place by pushing down on the extrusion. The design is parametric and can be easily customized for different sizes, either in OpenSCAD or via the online customizer.  The online customizer supports Misumi 15 mm and 20 mm extrusion, 1″ 1010-S and 20 mm 20-2020 from 80/20 Inc., 15 mm from OpenBeam and 10 mm from MicroRax. But it ought to be easy to create fresh designs in OpenSCAD. Check out the video after the break to see the bar-clamps in action.

If you’d like to start equipping your shop with more 3D printed tools, look no further. We’ve featured many types over the years, such as the StickVise and its Gooseneck System, this 3D printed rubber band PCB Vise, and even a 3D printed Mini-Lathe.

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Micro Chainsaw Gets a Much Needed Nitro Power Boost

When life hands you the world’s smallest chainsaw, what’s there to do except make it even more ridiculous? That’s what [JohnnyQ90] did when he heavily modified a mini-electric chainsaw with a powerful RC car engine.

The saw in question, a Bosch EasyCut with “Nanoblade technology,” can only be defined as a chainsaw in the loosest of senses. It’s a cordless tool intended for light pruning and the like, and desperately in need of the [Tim the Toolman Taylor] treatment. The transmogrification began with a teardown of the drivetrain and addition of a custom centrifugal clutch for the 1.44-cc nitro RC car engine. The engine needed a custom base to mount it inside the case, and the original PCB made the perfect template. The original case lost a lot of weight to the bandsaw and Dremel, a cooling fan was 3D-printed, and a fascinatingly complex throttle linkage tied everything together. With a fuel tank hiding in the new 3D-printed handle, the whole thing looks like it was always supposed to have this engine. The third video below shows it in action; unfortunately, with the engine rotating the wrong direction and no room for an idler gear, [JohnnyQ90] had to settle for flipping the bar upside down to get it to cut. But with some hacks it’s the journey that interests us more than the destination.

This isn’t [JohnnyQ90]’s first nitro rodeo — he’s done nitro conversions on a cordless drill and a Dremel before. You should also check out his micro Tesla turbine, too, especially if you appreciate fine machining.

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A Resistor Cutting Robot You Can Build

If you’re populating kits, it can get tiring and time consuming. Like all good repetitive processes, it should be automated. As far as cutting resistors goes, this is one way to do it, thanks to [Pablo].

The build is actually cribbed from earlier work by a gang called [oomlout]. Parts for these cutters are made with either lasercut or CNC milled sheet stock. A stepper motor is used to transport the resistor tape, and the cutting blades are moved by standard hobby servos. The use of servos for the blades allows the action to be controlled precisely without having to go to the effort of implementing extra limit switches and circuitry.

Control is by an Arduino Uno, with an A4988 driver controlling the stepper. Servo control is achieved with the Uno’s onboard peripherals. There’s a video below of the machine in operation, which shows it to be a simple and efficient tool for the job.

This build turns an otherwise maddeningly basic chore into a set-and-forget operation. We’ve seen other work in this area before from the [oomlout] team, too. Video after the break.

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What to do with Your Brand New Ultrasonic Transducer

We wager you haven’t you heard the latest from ultrasonics. Sorry. [Lindsay Wilson] is a Hackaday reader who wants to share his knowledge of transducer tuning to make tools. The bare unit he uses to demonstrate might attach to the bottom of an ultrasonic cleaner tank, which have a different construction than the ones used for distance sensing. The first demonstration shows the technique for finding a transducer’s resonant frequency and this technique is used throughout the video. On the YouTube page, his demonstrations are indexed by title and time for convenience.

For us, the most exciting part is when a tuned transducer is squeezed by hand. As the pressure increases, the current drops and goes out of phase in proportion to the grip. We see a transducer used as a pressure sensor. He later shows how temperature can affect the current level and phase.

Sizing horns is a science, but it has some basic rules which are well covered. The basic premise is to make it half of a wavelength long and be mindful of any tools which will go in the end. Nodes and antinodes are explained and their effects demonstrated with feedback on the oscilloscope.

We have a recent feature for an ultrasonic knife which didn’t cut the mustard, but your homemade ultrasonic tools should be submitted to our tip line.

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A Pin Pusher To Make Life Easier

Picture the scene: you’ve whipped up an amazing new gadget, your crowdfunding campaign has gone well, and you’ve got a couple hundred orders to fill. Having not quite hit the big time, you’re preparing to tackle the production largely yourself. Parts begin to flood in, and you’ve got tube after tube of ICs ready to populate your shiny new PCBs? After the third time, you’re sick and tired of fighting with those irksome little pins. Enter [Stuart] with the answer.

It’s a simple tool, attractively presented. Two pieces of laser cut acrylic are assembled in a perpendicular fashion, creating a vertical surface which can be used to press pins out of IC tubes. [Stuart]’s example has rubber feet, though we could easily see this built into a work surface as well.

The build highlights two universal truths. One, that laser cutters are capable of producing elegant, visually attractive items almost effortlessly, something we can’t say about the garden variety 3D printer. Secondly, all it takes is a few little jigs and tools to make any production process much easier. This is something that’s easy to see in the many factories all over the world – special single-purpose devices that make a weird, tricky task almost effortless.

In DIY production lines, testing is important too – so why not check out this home-spun test jig?

Tachometer Uses Light, Arduinos

To measure how fast something spins, most of us will reach for a tachometer without thinking much about how it works. Tachometers are often found in cars to measure engine RPM, but handheld units can be used for measuring the speed of rotation for other things as well. While some have mechanical shafts that must make physical contact with whatever you’re trying to measure, [electronoobs] has created a contactless tachometer that uses infrared light to take RPM measurements instead.

The tool uses an infrared emitter/detector pair along with an op amp to sense revolution speed. The signal from the IR detector is passed through an op amp in order to improve the quality of the signal and then that is fed into an Arduino. The device also features an OLED screen and a fine-tuning potentiometer all within its own self-contained, 3D-printed case and is powered by a 9 V battery, and can measure up to 10,000 RPM.

The only downside to this design is that a piece of white tape needs to be applied to the subject in order to get the IR detector to work properly, but this is an acceptable tradeoff for not having to make physical contact with a high-speed rotating shaft. All of the schematics and G code are available on the project site too if you want to build your own, and if you’re curious as to what other tools Arduinos have been used in be sure to check out the Arduino-based precision jig.

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