DIY Mini Fridge Is Pure Brilliance In Foam

February 18, 2023 by Lewin Day 54 Comments

There’s nothing more pleasing on a hot day than an ice-cold beverage. While the vast majority of us have a fridge in the kitchen, sometimes it’s desirable to have a further fridge in the lab, games room, or workshop. To that end, you may find value in this ultra-cheap, low-cost DIY fridge build from [Handy_Bear].

Like many tiny fridge builds, this design eschews complex gas-cycle refrigeration techniques for simple Peltier modules. These are devices that have one cold side and one hot side, because they move heat when electricity is applied. This build uses a Peltier module fitted with a fan to better shift away heat from the hot side, improving the module’s cooling ability.

The “fridge” itself is assembled out of thick XPS insulation foam. A hot wire cutter was used to cut several slabs which were then assembled using hot glue. The Peltier module is installed on the back, at the top of the fridge. Thus, air which is cooled in this area will then travel down through the rest of the fridge’s cavity. [Handy_Bear] also goes over how to produce a working hinge and a gasket for the door, which helps with ease-of-use and efficiency. As a nice touch, a set of 12V LED lights are also installed inside, which light when the door is open. Just like the real thing!

The final build is noisy, slow to cool down, and it uses 60 watts of power to cool down just two regulation-sized sodas. Notably, you could fit two standard NATO smoke grenades in the same space, as they’re almost-identically sized (ask us how we know). However, smoke grenades don’t usually need to be refrigerated.

None of that means it isn’t fun though! Plus, [Handy_Bear] notes that adding a second Peltier would greatly aid the fridge’s ability to quickly chill your ~~grenades~~ sodas. You might even like to explore the use of special fan designs to make the fridge even quieter! Video after the break.

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Self-Watering Planters Reuse Household Jars

January 29, 2023 by Donald Papp 9 Comments

Self-watering planters are low-maintenance, and common DIY projects. What we like most about [Tommy]’s design is that it reuses empty jars to create self-watering planters. After all, jars are fantastic at reliably holding water, so why not put them to work? Incorporating jars as part of the design means fewer worries about leakage, but it also means less 3D printing is needed overall.

A wick (in this case, a piece of string) takes care of moving water from jar to the soil.

[Tommy]’s planter screws onto the threads of a jar’s neck. Getting water to the plant is helped by a small piece of string, which acts as a wick between the soil at the top and the water in the jar at the bottom. This design works best with small plants, but on the plus side there are no moving parts or other complexities. Got a 3D printer? Models for the planter are available here.

The biggest challenge for this design is that not all jar threads are alike, so planters made in this way are not completely interchangeable across all different types of jars. Fortunately, [Tommy] provides the OpenSCAD code he used to generate his design, which he created with the help of an industry guide on how to measure the finish (or threads) of jars and lids.

If you find yourself needing to further customize your own version to fit a particular container’s threads, there’s no need to start from scratch. Unsurprisingly, threads and lids are highly standardized so chances are there exists a calculator, tool, or existing model for exactly what you need.

Off-Grid Van Build Uses 3D Scanning For Smarter Planning

January 22, 2023 by Donald Papp 44 Comments

Folks who refurbish and rebuild vans into off-grid campers (especially with the ability to work in them remotely) put a fantastic amount of planning and work into their projects. [Rob] meticulously documented his finished van conversion and while he does a ton of clever work, we especially liked how he shows modern tools like photogrammetry can improve the process.

Photogrammetry helped turn a bunch of photos from different angles into a textured 3D model with accurate dimensions.

[Rob] used a camera and photogrammetry software to 3D scan the van inside and out. The resulting model means that CAD tools can better assist with the layout and design phase. This is an immense help, because as [Rob] points out, an empty van is anything but a hollow box on wheels. Every surface is curved, none of the sides are identical, and there frankly isn’t a right angle to be found anywhere. When every little scrap of space counts, it’s important to have an accurate reference.

Of course, mapping the work are was just the beginning. It took six months, but he turned a Volkswagen Crafter cargo van into a slick off-grid camper capable of remote work. The full series of videos is on his site, but you can also watch the video highlights, embedded below.

The photogrammetry was done with Meshroom, and if you’d like to know more, we’ve previously explained different 3D scanning methods and how they can help with design work like this.

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Weatherproof Raspberry Pi Camera Enclosure, In A Pinch

January 18, 2023 by Donald Papp 17 Comments

The Raspberry Pi is the foundation of many IoT camera projects, but enclosures are often something left up to the user. [Mare] found that a serviceable outdoor enclosure could be made with a trip to the hardware store and inexpensive microscopy supplies.

A suitably-sized plastic junction box is a good starting point, but it takes more than that to make a functional enclosure.

The main component of the enclosure is a small plastic junction box, but it takes more than a box to make a functional outdoor enclosure. First of all, cable should be run into the box with the help of a cable fitting, and this fitting should be pointed toward the ground when the enclosure is mounted. This helps any moisture drip away with gravity, instead of pooling inconveniently.

All wire connections should be kept inside the enclosure, but if that’s not possible, we have seen outdoor-sealed wire junctions with the help of some 3D-printing and silicone sealant. That may help if cable splices are unavoidable.

The other main design concern is providing a window through which the camera can see. [Mare] found that the small Raspberry Pi camera board can be accommodated by drilling a hole into the side of the box, cleaning up the edges, and securing a cover slip (or clover glass) to the outside with an adhesive. Cover slips are extremely thin pieces of glass used to make microscope slides; ridiculously cheap, and probably already in a citizen scientist’s parts bin. They are also fragile, but if the device doesn’t expect a lot of stress it will do the job nicely.

[Mare] uses the Raspberry Pi and camera as part of Telraam, an open-source project providing a fully-automated traffic counting service that keeps anonymized counts of vehicle, pedestrian, and bicycle activity. Usually such a device is mounted indoors and aimed at a window, but this enclosure method is an option should one need to mount a camera outdoors. There’s good value in using a Raspberry Pi as a DIY security camera, after all.

Make Your Own Pot And Encoder Knobs, Without Reinventing Them

January 14, 2023 by Donald Papp 10 Comments

Rotary potentiometers, switches, and encoders all share a basic design: adjustment is done via a shaft onto which a knob is attached, and knobs are sold separately. That doesn’t mean one knob fits all; there are actually a few different standards. But just because knobs are inexpensive and easily obtained doesn’t mean it’s not worth making your own.

A simple and effective indicator can be easily printed in a contrasting color.

Why bother 3D printing your own knobs instead of buying them? For one thing, making them means one can rest assured that every knob matches aesthetically. The ability to add custom or nonstandard markings are another bonus. Finally, there’s no need to re-invent the wheel, because [Tommy]’s guide to making your own knobs has it all figured out, with the OpenSCAD script to match.

By default, [Tommy]’s script will generate a knob with three shims (for interfacing to a splined shaft) when pot_knob(); is called. The number of shims can be adjusted by modifying potKnobDefaultShimCount. To give the knob a flat side (to interface with D-shafts), change flatted = false to flatted = true. And for adding a screw insert suitable for a set screw? Change tightenerDiameter = 0 from zero to the diameter desired.

The script is quite comprehensive and has sensible defaults, but it does require a bit of knowledge about OpenSCAD itself to use effectively. We have covered the basics of OpenSCAD in the past, and if you’re ready for a resource that will help you truly master it, here’s where to look.

DIY Magnet Handling Tool Puts An End To Placement Errors

January 14, 2023 by Donald Papp 10 Comments

I’m sure we can all agree that the worst time to find out a magnet is the wrong way around is after glue has been applied. With that in mind, [erick.siders] created the parametric Magnet Placer tool.

Color-coded tools, one for each polarity.

Picking up and placing magnets into assemblies can be an error-prone process, because magnet polarity cannot be directly identified or sensed by either sight or fingertips. This tool helps by acting a lot like a suction pickup tool — press the plunger down, and a magnet can be picked up, release the plunger, and the magnet lets go. Simple, and effective.

Since the tool is polarity-dependent (depending on which orientation the pickup magnet is mounted into the internal plunger), [erick.siders] suggests printing two tools and color-coding them. That way, one can choose the right tool based on the situation and be confident that the magnets are right-side-up, every time.

The tools use a long metric bolt, a magnet, and a spring, but none of those parts are particularly critical. We also love the way that the end result has no gaps or openings into the moving parts, which means nothing can get caught on or inside anything during use or storage.

It’s a parametric design and the CAD files (in both Fusion 360 and STEP flavors) are provided, so modification should be a breeze. And if you happen to be using PrusaSlicer, remember you can now drop STEP format files directly in for slicing.

A Hacker’s Christmas Story

December 24, 2022 by Elliot Williams 11 Comments

Twas the night before Christmas, and because I decided to make everyone’s presents myself this year, I’m still working like mad to get everything done before the big deadline. Why do I do this to myself? Well, partly because I enjoy the process.

My wife had this idea that we can make the older folks some fun decorative blinky things, and picked some motives. My son then drew them out on paper, and I scanned those drawings in and traced them over in CAD. We then cut the shapes out of wood on the CNC router, which turned out to be incredibly successful. (Now that I’ve done it, I wouldn’t be surprised if all of those “quirky” decorative objects that the Swedish flat-packers sell aren’t initially sketched out by third graders.)

Then my son painted them, and it’s my job to insert the twinkling. I bought some of those three-wire “fairy lights” for the purpose, and they’re really fun to hack on. They’re like WS2812s, only instead of using four pins and shifting the data downstream, they’re on a bus, each with a hard-coded address – they know where they are in the string and each LED only listens for the Nth set of 24 bits. This means sending 200 color codes just to light up the 4 LEDs in Aunt Micki’s decorative tree, but so be it.

Last stop, and still to do as of the 23rd, route out some kind of wooden battery case, wedge in the LiPo and the charging circuits, and solder on an on/off switch. It’s down to the last minute, but isn’t that always the way?

Definitely would have been easier just to order something online. But is that the spirit of giving? No! The DIY way brings the family together, gets me some quality time with the CNC machine, and tones up my FreeCAD skills. My son even looked over my shoulder as we were coding some of the LED animations. And nothing says Christmas like hand-coded blinkies.

Happy Holidays, y’all!