how-to

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Hardware hacking how-tos

Build A Tiny Hot Wire Foam Cutter

February 8, 2018 by 34 Comments

Let’s face it: cutting foam with a knife, even a serrated plastic knife meant for the job, is a messy pain in the ass.  This is as true for insulation board as it is for the ubiquitous expanded polystyrene kind of foam used for everything from coffee cups to packaging material.

Those stick-type hot wire cutters from the craft store that plug into the wall aren’t much better than a knife. The actual cleaving of foam is easier, but dragging a long, hot flexible wand through rigid foam just right, without making burn marks, is pretty frustrating. It’s not like you can hold the other end to keep it steady. A foam cutter built like a coping saw but held parallel to the wire would offer much better control.

[Techgenie]’s handheld hot wire foam cutter is a simple build based on a single 18650 and a piece of nichrome wire. While this is probably not the most Earth-shattering hack you’ll see today, it’s a useful tool that can be made in minutes with items on hand. Laptop chargers are full of 18650s, and nichrome wire can be sourced from old toasters, hair dryers, or space heaters.

You shouldn’t use just any old wire for this, though, or the battery will get hot and potentially explode. Nichrome wire has a high resistance, and that’s exactly what you want in a tool that essentially shorts a battery to make heat. [Techgenie] used a momentary button instead of a switch, which is a good way to stay safe while using it. It wouldn’t hurt to add some protection circuitry and take the battery out when you’re done. Burn past the break to watch him build it and cut a few tight turns with ease.

If you have bigger, more complicated foam-cutting jobs in mind, why not build a CNC version out of e-waste?

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A Freeze Dryer You Can Build In Your Garage

February 7, 2018 by 41 Comments

What do trail mix, astronaut ice-cream, and cryogel have in common? This may sound like the introduction to a corny riddle, but they are all things you can make in your garage with a homemade freeze dryer. [The Thought Emporium] built his own freeze dryer with minimum fuss and only a few exotic components like a vacuum pump and a high-quality pressure gauge. The video is also posted after the break which contains a list for the parts and where they can be purchased.

Freeze drying uses a process called cryodesiccation or lyophilization. Below a certain pressure, water skips the liquid phase and goes directly to a gas, so frozen items can transition from ice to dry without a soggy step. When you jump the liquid phase, objects hold their shape when they were frozen, and since no heat is used, you don’t carmelize your sugars.

A freeze-dryer like this has three parts. The first is the pump which doesn’t need any explanation. Next to the pump there must be a water trap. This chilly compartment recondenses the water vapor, so it doesn’t get inside the pump or saturate the things you’re trying to dry. Lastly, there is the drying chamber where your items are placed to have their moisture taken out.

Astronaut ice cream has been made on Hackaday before. [The Thought Emporium] has also been seen including a piece on making your own graphene.

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Disco Bulb Keeps The Party Spinning

January 27, 2018 by 12 Comments

Even if you don’t like disco, you might like the slick moves that went into this project. [W&M] built a miniature motorized mirror ball inside of a standard incandescent light bulb, and the results are something to dance about.

Short of blowing a glass bulb, building a motor, and growing the wood, this is about as scratch-built as it gets. Much of the woodworking is done on a metal lathe, and this includes the base of the mirror ball itself. As with all good thing-in-a-bottle builds, the ball is too big to go in the bulb, so [W&M] quartered it, drilled a few holes, and ran a string through the pieces so they can be carefully glued and drawn back together into a sphere. He even cut up mirror tiles and painstakingly applied them with tweezers.

This disco bulb is meant to be hung from the ceiling and wired into mains like a regular mirror ball. [M&W] stuffed the guts from a small USB wall charger into the handmade beech base to provide clean power for both the geared motor that spins the ball and the tiny LED that illuminates it. Slip into your best leisure suit (or sweat suit, we won’t judge) and hustle past the break to watch the build video.

We don’t see a lot of disco balls around here, but we did see a disco icosahedron once.

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Using Lasagna To Make Cost-Saving Molds

January 25, 2018 by 7 Comments

Building a one-off prototype is usually pretty straightforward. Find some perfboard and start soldering, weld up some scrap metal, or break out the 3D printer. But if you’re going to do a production run of a product then things need to have a little more polish. In [Eric Strebel]’s case this means saving on weight and material by converting a solid molded part into something that is hollow, with the help of some lasagna.

What [Eric] walks us through in this video is how to build a weep mold. First, the solid part is cast in silicone. Using the cast, some “sheet clay” is applied to the inside which will eventually form the void for the new part’s walls. The clay needs to be flush with the top of the mold, though, and a trick to accomplish this task is to freeze the mold (next to the lasagna) which allows the clay to be scraped without deforming.

From there, the second half of the mold is poured in, using special channels that allow the resin to “weep” out of the mold (hence the name). This two-part process creates a much more efficient part with thin walls, rather than the expensive solid prototype part.

[Eric] is no stranger around these parts, either. He’s an industrial designer with many tips and tricks of the profession, including a method for building a machining tool out of a drill press and a vise as well as some tips for how to get the most out of a low-volume production run of a product you might be producing.

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DIY Dungeon Crawler Game Plays On Single LED Strip

January 24, 2018 by 23 Comments

A delightful version of a clever one-dimensional game has been made by [Critters] which he calls TWANG! because the joystick is made from a spring doorstop with an accelerometer in the tip. The game itself is played out on an RGB LED strip. As a result, the game world, the player, goal, and enemies are all represented on a single line of LEDs.

How can a dungeon crawler game be represented in 1D, and how is this unusual game played? The goal is for the player (a green dot) to reach the goal (a blue dot) to advance to the next level. Making this more difficult are enemies (red dots) which move in different ways. The joystick is moved left or right to advance the player’s blue dot left or right, and the player can attack with a “twang” motion of the joystick, which eliminates nearby enemies. By playing with brightness and color, a surprising amount of gameplay can be jammed into a one-dimensional display!

Code for TWANG! is on github and models for 3D printing the physical pieces are on Thingiverse. The video (embedded below) focuses mainly on the development process, but does have the gameplay elements explained as well and demonstrates some slick animations and sharp feedback.

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The (Unnecessary?) Art Of Connector Crimping

January 20, 2018 by 54 Comments

The “Completion Backwards Principle” is a method of reasoning through a problem by visualizing the end result and then working your way backwards from that point. The blog post that [Alan Hawse] has recently written about the intricacies of crimping wires for plug connectors is a perfect example of this principle. The end result of his work is the realization that you probably shouldn’t bother crimping your own connectors, but watching him work backwards from that point is still fascinating. It’s also the name of a rock album from the 80’s by The Tubes, but this is not a useful piece of information in regards to electrical wiring.

Of course, sometimes people do silly things. Even though there are pre-crimped wires available online for a pittance, you might still want to do your own. With this in mind, [Alan] has put together an exceptionally detailed and well-research post that gives you all the information you could possibly want to know about crimping what is often erroneously referred to as the “JST connector”.

He starts by showing off some common examples of this connector, which if you’ve ever opened a piece of consumer electronics will be like looking through a High School yearbook. You might not know their names without reading them, but you definitely remember what they look like.

We’re then treated to an array of macro shots showing the scale of the pieces involved. If getting up close and personal with metal bits that are only a few millimeters long is your kind of thing, then you’re really going to love this part.

Finally, the post is wrapped up with a few words about the kind of crimping tools that are available on the market, and then a demonstration of his personal crimping method. While some tools would have you crimp both sets of “wings” at the same time, [Alan] tells us he finds taking them on individually leads to better results in his experience.

If this this little taste has left you hungry for a true feast of hyper-specialized knowledge, be sure to check out the Superconference talk by [Bradley Gawthrop].

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DIY Spray Booth Is Both Light And Lit

January 19, 2018 by 17 Comments

Industrial designer [Eric Strebel] has access to big, walk-in spray booths, but bigger isn’t always better. For small jobs, it’s overkill, and he wanted his own spray booth anyway. If you’re ready to upgrade from that ratty old cardboard box in the garage, look no further than [Eric]’s spray booth how-to after the break.

If you don’t already know, [Eric] is something of a foam core legend. He has several videos about model building techniques that produce really slick results, so it’s no surprise to see these skills transfer to a larger build. The booth is built from a single 40″ x 60″ sheet of 1/2″ foam core board, a furnace filter, and a vent fan modified to fit his shop’s system. The whole thing cost less than $200, most of which goes toward the fan.

[Eric] modified an existing spray booth plan to fit his needs and added some really nice touches along the way. All the edges are beveled and the unfinished faces are taped, so at first glance it looks like it’s made out of painted wood or melamine board. The furnace filter slides out one side for easy replacement and is braced with foam scraps so it won’t fall forward. The best part of this booth is the LED strips—they make for way better working conditions than the dim recesses of a cardboard box.

If you’d rather build a walk-in spray booth, why not make your own sliding barn doors, too?

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