Do You Really Need To Dry Filament?

November 29, 2021 by Dave Rowntree 46 Comments

There’s a lot of opinions and theories around the storing and drying of 3D printing materials. Some people are absolutely convinced you must bake filament if it been stored outside an airtight bag, even for a few days. Some others have ‘never had a problem.’ So it’s about time someone in the know has done some testing to try to pin down the answer to the question we’re all asking; How bad is wet filament really?

[Thomas Sanladerer] setup a simple experiment, using samples of three common types of filament, specifically PLA, PET-G and ASA. He stored the samples in three environments, on his desk, outside in the garden, and finally submerged in water for a full week. What followed was a whole lot of printing, but they all did print.

Different filaments will absorb water at different rates, depending upon their chemical composition and the environment, nylon being apparently particularly fond of a good soaking. It would seem that the most obvious print defect that occurs with increased water absorption is that of stringing, and other than being annoying and reducing surface quality somewhat, it’s not all that serious in the grand scheme of things. It was interesting to note that water absorption doesn’t seem to affect the strength of the final part.
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Line of electromechanical water valves dispensing a pattern of water droplets

Gravity-Defying Water Drop Display Shows Potential

October 23, 2021 by Dave Rowntree 9 Comments

[3DPrintedLife aka Andrew DeGonge] saw that advert for gatorade that shows some slick stop-motion animation using a so-called ‘liquid printer’ and wondered how they built the machine and got it to work so well. The answer, it would seem, involves a lot of hard work and experimentation.

Conceptually it’s not hard to grasp. A water reservoir sits at the top, which gravity-feeds into a a series of electromechanical valves below, which feed into nozzles. From there, the timing of the valve and water pressure dictate the droplet size. The droplets fall under the influence of gravity, to be collected at the bottom. From that point it’s a ‘simple’ matter of timing droplets with respect to a lighting strobe or camera shutter and hey-presto! instant animation.

As will become evident from the video, it’s just not as easy as that. After an initial wobble when [Andrew] realised that cheap “air-only” solenoids actually are for air-only when they rusted up, he took a slight detour to design and 3D print his own valve body. Using a resin printer to produce fine detailed prints, enabled the production of small internal passages including an ‘air spring’ which is just a small chamber of air. After a lot of testing, proved to be a step in the right direction. Whether this could have been achieved with an FDM printer, is open to speculation, but we suspect the superior fine detail capabilities of modern resin printers are a big help here.

In a nice twist, [Andrew] ripped open and dissolved a fluorescent marker pen, and used that in place of plain water, so when illuminated with suitably triggered UV LED strips, discernable animation was achieved, with an eerie green glow which we think looks pretty neat. All he needs to do now is upgrade the hardware to make a 3D array with more resolution, and he can start approaching the capability of the thing that inspired him. Work on some custom electronics to drive it has started, so this is one to watch in the coming months!

We’ve seen many water-based display device before, like this one that projects directly onto a thin stream of water, and this strangely satisfying hack using paraffin and water, but a full 3D Open Source display device seems elusive so far.

All project details can be found on the associated GitHub.

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Power Your Home With A Water Battery

October 8, 2021 by Matthew Carlson 69 Comments

I’ve stated it before on Hackaday but one of the most interesting engineering challenges posed to me this year was “how could you store enough energy to power a decent portion of a home for several hours without using batteries, all while staying within the size of a typical suburban plot?” [Quint Builds] attempts something up that alley by using solar power to pump water up onto his roof and later releasing it for power generation. (Video, embedded below.)

Earlier [Quint] had built a water collecting system using his gutters and a bell siphon but wasn’t satisfied with the overall power output. Using the turbine he had created for that system, he put a 55-gallon drum on top of his roof with the help of some supporting structures. We’d like to advise the public to consult a professional before adding a large heavy weight on top of your roof, but [Quint] forges ahead after studying his trusses and determining it to be a risk he is willing to take. A solar panel runs a small pump that pumps water from a reservoir up to the top of the roof when the sun shines with a float switch in the roof barrel stopping the motor once it’s full. A valve at the bottom allows water to spin the turbine and fill back into the bottom reservoir, forming a closed loop. There were a few snags along the way with prototype circuits not being fully contacted and the motor needing water cooling, an issue fixed by a custom CNC’d heat sink. The fixes for the various issues are almost as entertaining to see as the actual system itself.

It’s incredible to see lights come on powered by water alone but also sobering to realize just how much water you’d need to power a typical home. Perhaps if [Quint] upgrades, he can swap out the small motor for a larger 3D printed water pump.

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Lord Kelvin’s Contraption Turns Drips Into Sparks

July 22, 2021 by Tom Nardi 21 Comments

It’s easy to think that devices which generate thousands of volts of electricity must involve relatively modern technology, but the fact is, machines capable of firing sparks through open air predate Edison’s light bulb. Which means that recreating them with modern tools, construction techniques, and part availability, is probably a lot easier than most people realize. The fascinating machine [Jay Bowles] put together for his latest Plasma Channel video is a perfect example, as it’s capable of developing 6,000 volts without any electronic components.

Now as clever as [Jay] might be, he can’t take credit for the idea on this one. That honor goes to Lord Kelvin, who came up with this particular style of electrostatic generator back in 1867. Alternately called “Kelvin water dropper” or “Lord Kelvin’s Thunderstorm”, the machine is able to produce a high voltage charge from falling water without using any moving parts.

Diverging streams means a charge is building up.

Our very own [Steven Dufresne] wrote an in-depth look at how these devices operate, but the short version is that a negative and positive charge is built up in two sets of metallic inductor rings and buckets, with the stream of water itself acting as a sort of wire to carry the charge up to the overhead water reservoir. As [Jay] demonstrates the video, you’ll know things are working when the streams of water become attracted to the inductors they are passing through.

Rather than connecting a separate spark gap up to the water “receivers” on the bottom of his water dropper, [Jay] found the handles on the metal mugs he’s using worked just as well. By moving the mugs closer and farther away he can adjust the gap, and a second adjustment lets him move the vertical position of the inductors. It sounds like it takes some fiddling to get everything in position, but once it’s working, the whole thing is very impressive.

Of course if you’re looking to get serious with high voltage experiments, you’ll want to upgrade to some less whimsical equipment pretty quickly. Luckily, [Jay] has shown that putting together a reliable HV supply doesn’t need to be expensive or complicated.

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Soil Moisture Sensors, How Do They Work?

May 17, 2021 by Donald Papp 19 Comments

In a way, the magic of a soil moisture sensor’s functionality boils down to a simple RC circuit. But of course, in practice there is a bit more to it than that. [rbaron] explains exactly how capacitive soil moisture sensors work simply, clearly, and concisely. He also shows, with a short video, exactly how their output changes in response to their environment, and explains how it informed his own sensor design.

At its heart, a moisture sensor measures how quickly (or slowly) a capacitor charges through a resistor, but in these sensors the capacitor is not a literal component, but is formed by two PCB traces that are near one another. Their capacitance — and therefore their charging rate — changes in response to how much water is around them. By measuring this effect on a probe sunk into dirt, the sensor can therefore indirectly measure the amount of water in the soil.

This ties into his own work on b-parasite: an open-source, all-in-one wireless soil moisture sensor (which was also a runner-up in our Earth Day contest) that broadcasts over BLE and even includes temperature readings. One thing to be mindful of if you are making your own PCBs or ordering them from a fab house is that passing current through metal in a moist environment is a recipe for oxidation, so it’s important not to expose bare traces to wet soil. A good coated PCB should avoid this problem, but one alternative we have seen proposed is to use graphite rods in place of metal.

Earth Day Challenge: A Better Way To Wrangle Water

March 25, 2021 by Kristina Panos 26 Comments

How far do you have to go for a glass of clean water? Not very? Just go to a sink and turn on the faucet? We would venture to guess that is the case for most Hackaday readers. Maybe you even have a water softener, or a filter on your tap to make your drinking water even more palatable and free of heavy metal.

In Ethiopia and many other countries, people do not have access to clean, flowing water and must walk several kilometers to fetch it from somewhere that does. And they’re not doing this on paved roads, either — these women are cutting treacherous paths across mountains and through muddy, rocky terrain that make wheeled transport nearly impossible. How do you comfortably lug around 25 kg (~55 lbs) worth of sloshing water? You don’t, unless you have [Anteneh Gashaw]’s ingenious jerrycan.

As you can see in the video below, the current crop of jerrycans are just big plastic jugs that have to be carried on top of the head or the shoulder, both of which are bad for bodies. [Anteneh]’s can evenly distributes the weight by wrapping it completely around the person carrying it and suspending it from both shoulders like a beer-and-peanuts vendor’s carrying case. Basically, it’s a PVC inner tube with shoulder straps. Simple, cheap, and effective = absolute genius in our book. Ideally, everyone would have free access to clean water, both cold and hot. Until that time, [Anteneh]’s entry into our Earth Day Challenge is a great workaround that will no doubt save a lot of spines.

Potable water may be closer than you think. Build a portable potability predictor and you might not have to travel so far.

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Ask Hackaday: How Do You Prepare?

March 24, 2021 by Jonathan Bennett 140 Comments

Last month, large parts of the southern United States experienced their coldest temperatures since the 1899 Blizzard. Some of us set new all-time lows, and I was right in the middle of the middle of it here in Southwestern Oklahoma. Since many houses in Texas and Oklahoma are heated with electricity, the power grids struggled to keep up with the demand. Cities in Oklahoma experienced some short-term rolling blackouts and large patches of the Texas grid were without power for several days. No juice, no heat.

In places where the power was out for an extended period of time, the water supply was potentially contaminated, and a boil order was in effect. Of course, this only works when the gas and power are on. In some places, the store shelves were empty, a result of panic buying combined with perishables spoiling without the power to keep them cold. For some, food and drinkable water was temporarily hard to come by.

There have been other problems, too. Houses in the south aren’t built for the extreme cold, and many have experienced frozen pipes, temporarily shutting off their water supply. In some cases, those frozen pipes break open, flooding the house once the water starts flowing again. For instance, here’s an eye-witness account of the carnage from The 8-bit Guy, who lives at ground zero in the DFW area.
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