3D Printed Magnetic Stirrer Could Hardly Be Simpler

March 21, 2018 by Al Williams 11 Comments

If you’ve spent much time in a chemistry or biology lab, you’ve probably seen a magnetic stirrer. This is a little table that you put a beaker on. A little bar (often called a flea or a pill) goes in the solution and spins to stir the beaker’s contents. Simple versions are not that expensive, but nicer ones can cost a bit. [John] decided to build his own using 3D printing and the design is delightfully simple.

The electronics is nothing more than a PC fan, an off-the-shelf fan controller with a display, and a 3D printed bracket with some magnets. The flea is also 3D printed, although we’d probably buy cheap commercial fleas since they are usually coated with Teflon or some other non-reactive substance. Depending on what you are stirring, the reactivity of your 3D printed plastic and its porosity could be a concern. In addition, a commercial flea has a pivot ring that helps it spin smoothly, although we are sure the 3D printed one will work in most cases.

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Building A Static Grass Applicator

March 21, 2018 by Tom Nardi 16 Comments

A “Static Grass Applicator” is very specialized tool used by model makers to create realistic grass. Don’t feel bad if you didn’t know that, neither did we. Anyway, the idea is that you distribute a fine filament over the surface, and then use static electricity to make the “blades” of grass stand up vertically. This is a huge improvement over the old school method of manually placing the grass on the model, but the tool itself is somewhat expensive, at least for a decent one.

But thanks to avid modeler [Luke Towan], those looking to up their diorama game without breaking the bank now have a fantastically detailed guide on building their own grass applicator that is not only fairly cheap (as little as $20 USD depending on what your part bins look like), but is robust enough to last for years of service.

The heart of the device, and probably the only part you’d need to go out and buy especially for this project, is a small 12V negative ion generator. This is used to setup an electric charge between the grid of the applicator and a long wire that gets attached to the piece you’re working on. What little wiring there is simply provides a switch and some status LEDs. The design [Luke] has come up with lets the user switch between and internal 9V battery for portability, or an external 12V wall adapter for larger projects.

Building the chamber to hold the grass filament as well as the handle which houses the electronics will take longer than anything else, and even that seems pretty straightforward. Given the impressive results shown in the video after the break, it’s actually pretty surprising how simple the device is.

The setup used here reminds us of the DIY powder coating we covered a few years back.

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Make A Steam Cleaner From A Broken Clothes Iron

March 20, 2018 by Richard Baguley 2 Comments

As the old saying goes, when life gives you a broken iron, make a steam cleaner. Or something like that. Anyway, [Claudio] from [Accidental Science] had a clothes iron with a broken head that he decided to adapt into a steam blower that can be used to clean PCBs, glassware, degreasing parts or cleaning stains off the couch.

[Claudio] covers everything from tearing down the broken iron to crafting a new tip that avoids problems with water droplets condensing on the brass tip that he used first. After salvaging the switch in the head that controls the steam, he carved a wooden handle that is soaked and coated with high-temperature resin. The hot end was then reinstalled, and the whole thing put together.

This build should be approached with some caution, though: anything that mixes high-pressure steam with electricity has the potential to go wrong in unpleasant ways, so be careful out there.

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DIY Power Supply And TS100 Outlet Combo Shows Off Great Layout

March 19, 2018 by Donald Papp 18 Comments

Here’s a combination of two important electronics workbench tools into a single, cleanly-assembled unit. [uGen] created a DC power supply complete with a plug for the popular TS100 soldering iron, and it looks great! Most of the main components are familiar offerings, like a LM2596 DC to DC buck converter board and a DPS3003 adjustable DC power supply unit (we previously covered a DIY power supply based around the similar DPS5005.) The enclosure is an economical, featureless desktop instrument case whose panels were carefully cut to fit the necessary components. There’s one limitation to the combo: the unit uses a switch to either power an attached TS100 iron, or act as a general DC power supply. It cannot do both at once. So long as one doesn’t mind that limitation, it’s a nice bundle made from very affordable components.

It’s easy for something to look like a hack job, but to look clean and professional involves thoughtful measurement, planning, and assembly. Fortunately, [uGen] has supplied all the drawings and bill of materials for the project so there’s no need to start from scratch. Also, don’t forget that if the capabilities of the DPS power supply units leave you wanting a bit more, there is alternative firmware in the form of OpenDPS; it even offers a remote control feature by adding an ESP8266.

3D Printed Stethoscope Makes The Grade

March 17, 2018 by Tom Nardi 22 Comments

On the off chance that initiatives like the Hackaday Prize didn’t make it abundantly clear, we believe strongly that open designs can change the world. Putting technology into the hands of the people is a very powerful thing, and depending on where you are or your station in life, can quite literally mean the difference between life and death. So when we saw that not only had a team of researchers developed a 3D printable stethoscope, but released everything as open source on GitHub, it’s fair to say we were pretty interested.

The stethoscope has been in development for several years now, but has just recently completed a round of testing that clinically validated its performance against premium brand models. Not only does this 3D printed stethoscope work, it works well: tests showed its acoustic performance to be on par with the gold standard in medical stethoscopes, the Littmann Cardiology III. Not bad for something the researchers estimate can be manufactured for as little as $3 each.

All of the 3D printed parts were designed in OpenSCAD (in addition to a Ruby framework called CrystalSCAD), which means the design can be evaluated, modified, and compiled into STLs with completely free and open source tools. A huge advantage for underfunded institutions, and in many ways the benchmark by which other open source 3D-printable projects should be measured. As for the non-printed parts, there’s a complete Bill of Materials which even includes links to where you can purchase each item.

The documentation for the project is also exceptional. It not only breaks down exactly how to print and assemble the stethoscope, it even includes multi-lingual instructions which can be printed out and distributed with kits so they can be assembled in the field by those who need them most.

From low-cost ultrasounds to truly personalized prosthetics, the future of open source medical devices is looking exceptionally bright.

[Thanks to Qes for the tip]

A Pin Pusher To Make Life Easier

March 15, 2018 by Lewin Day 67 Comments

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?

Building A Portable Solar-Powered Spot Welder: Nearly Practical!

March 15, 2018 by Sean Boyce 18 Comments

Last time, we covered storing and charging a 3000 Farad supercapacitor to build a solar-powered, portable spot welder. Since then, I’ve made some improvements to the charging circuit and gotten it running. To recap, the charger uses a DC-DC buck converter to convert a range of DC voltages down to 2.6 V. It can supply a maximum of 5 A though, and the supercapacitor will draw more than that if allowed to.

Capacitor charge current decreases with time as the capacitor charges. Source: Hyperphysics

After some failed attempts, I had solved that by passing the buck converter output through a salvaged power MOSFET. A spare NodeMCU module provided pulse width modulated output that switched the MOSFET on for controlled periods of time to limit the charging current. That was fine, but a constant-voltage charger really isn’t the right way to load up a capacitor. Because the capacitor plates build up a voltage as it charges, the current output from a constant-voltage charger is high initially, but drops to a very low rate in the end.

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