In Space, No One Can Hear You Explode: The Byford Dolphin Incident

“It wouldn’t happen that way in real life.” One of the most annoying habits of people really into the “sci” of sci-fi is nitpicking scientific inaccuracies in movies. The truth is, some things just make movies better, even if they are wrong.

What would Star Wars be without the sounds of an epic battle in space where there should be no sound? But there are plenty of other examples where things are wrong and it would have been just as easy to get them right — the direction of space debris in the movie Gravity, for example. But what about the age-old trope of explosive decompression? Some movies show gross body parts flying everywhere. Others show distressed space travelers surviving in space for at least brief periods.

It turns out, dropping pressure from one atmosphere to near zero is not really good for you as you might expect. But it isn’t enough to just make you pop like some meat balloon. You are much more likely to die from a pulmonary embolism or simple suffocation. But you are a meat balloon if you experience a much greater change in pressure. How do we know? It isn’t theoretical. These things have happened in real life.

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A Crash Course In 3D Printed Venturi Pumps

Venturi pumps, commonly referred to as aspirators, are a fantastic way of moving around things which you might not want spinning around inside of a pump, and one of the easiest ways to create a vacuum. According to his research, [Tuval Ben Dosa] believed such a device would be a good way to move corrosive gasses which would normally eat up a blower fan; all he had to do was figure out how to 3D print one to his specifications.

Put simply: if you take a “T” shaped pipe and pass a fluid (such as air or water) through the straight section, a vacuum will be created on the shorter side due to the Venturi effect. As long as you don’t mind the substance you wish to pump getting mixed into your working fluid, it’s a simple way to bring something “along for the ride” as the fluid makes its way through the pipe.

[Tuval] needed a way to remove the chlorine gasses produced by his PCB etching station, and an aspirator seemed like the perfect solution. He just needed to pump clean air through a Venturi, which would suck up the chlorine gas on the way through, and ultimately carry it outside. But he soon found that while a pump based on the Venturi effect is simple conceptually, getting it to work in the real world is a bit trickier. Especially when you’re dealing with something like 3D printing, which brings in its own unique challenges.

He tried modeling a few designs he found online in 3D and printing them out, but none of them worked as expected. The most common problem was simply that no vacuum was being generated, air was freely moving out of both sides. While [Tuval] doesn’t claim to have any great knowledge of fluid dynamics, he reasoned that the issue was due to the fact that most Venturi pumps seem designed to move water rather than air. So he designed a new version of the pump which had a more pronounced nozzle on the inlet surrounded by a cavity in which the gases could mix.

His modified design worked, and now anyone with a 3D printer can run off their own Venturi device for quickly and easily giving potentially harmful fumes or gases the boot. If this is one of those things you’d feel more comfortable buying than building, don’t worry, we’ve previously covered using a low-cost aspirator as a vacuum source in the home lab.

Automate Your Comfort Food Prep with an IoT Grilled Cheese Robot

What exactly qualifies as comfort food is very much in the palate of the comfortee. Grilled cheese may not work for everyone under every circumstance, but we’ll risk a bet that the gooey delicacy is pretty close to universal, especially when you’re under the weather.

But if you’re too sick to grill up your own and don’t have anyone to do it for you, this grilled cheese sandwich-making robot might be the perfect kitchen accessory. Dubbed “The Cheeseborg” and built as a semester project by [Taylor Tabb], [Mitchell Riek], and [Evan Hill] at Carnegie-Mellon University, the bot takes a few shortcuts that might rankle the grilled cheese purist. Chief among these is the use of a sandwich press rather than a plain griddle. We understand that this greatly simplifies the flipping problem, but to us the flipping, especially the final high arcing double backflip onto the sandwich plate, is all part of the experience. Yes, a fair number of sandwiches end up going to the dog that way, but that’s beside the point.

As realized, Cheeseborg feeds bread and cheese from stacks using a vacuum arm, sprays the grill with butter, and uses a motorized arm to push the uncooked sandwich into the press. At the peak of grilled perfection, the press opens and ejects the sandwich to a waiting plate. As an added bonus, the whole thing is Google Assistant enabled so you can beseech Cheeseborg to fix you a sandwich from your sick bed. See it in action below.

This is far from the first culinary robot to grace our pages. There was the recent CNC sausage bot, we’ve seen plenty of pancake bots, and even [Ben Krasnow] once automated cookie making.

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Down the DIY Rabbit Hole with a Shop AC Installation

There’s a fine line between a successful DIY project and one that ends in heartbreak. It’s subjective too; aside from projects that end up with fire trucks or ambulances in the driveway, what one DIYer would consider a disaster might be considered a great learning opportunity to someone else.

We’re pretty sure [Cressel] looks at his recent DIY mini-split AC installation for his shop as a series of teachable moments. Most folks leave HVAC work to the pros, but when you run a popular YouTube channel where you make your own lathe from scratch, you might be persuaded to give anything a go. [Cressel] did everything possible to do this job like a pro, going so far as to get training in the safe handling of refrigerants and an EPA certification so he knew how to charge the system correctly. He also sunk quite a bit of money into tools; between the manifold gauge set, vacuum pump, and various plumbing bits, that was a hefty $300 bite alone.

The install went well until he started charging the refrigerant, when a mistake with a fitting caused him to contaminate his nice, new batch of R-410A. Rather than back out and call a pro to finish up, [Cressel] stuck with it, to the tune of $900 in extra tools and materials needed to recover the old refrigerant safely and replace it with virgin R-410A. The video below has a condensed version of the whole tale.

It all worked out in the end, but at a cost that probably meets or exceeds what an HVAC contractor would have charged. [Cressel] seems like a glass-half-full kind of guy, though, so we expect he’s happy to have learned something new, and to have a bunch of neat new tools to boot.

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Custom Coaxial Dust Collector Makes CNC Router a Clean Machine

Everyone loves firing up that CNC router for the first time. But if the first thing you cut is wood, chances are good that the second thing you cut will be parts for some kind of dust shroud. Babysitting the machine and chasing the spindle around with a shop vac hose probably isn’t why you got it in the first place, right?

Trouble is, most dust-management designs just don’t get the job done, or if they do, they obstruct your view of the tool with a brush or other flexible shroud. [Jeremy Cook] figured he could do better with this coaxial dust collector, and from the practically dust-free cuts at the end of the video below, we think he’s right. The design is a two-piece, 3D-printed affair, with a collar that attaches to the spindle and a separate piece containing the duct. The two pieces stick together with magnets, which also lets the shroud swivel around for optimal placement. The duct surrounds the collet and tool and has a shop vac hose connection. In use, the vacuum pulls a ton of air through small opening, resulting in zero dust. It also results in the occasional part sucked up from the bed, so watch out for that. [Jeremy] has published the STL files if you want to make your own.

We’re pretty impressed, but if you still feel the need for a physical shroud, check out this shaggy-dog design that seems to work well too. Or you could just throw the whole thing in an enclosure.

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3D Printed Magnetic Dust Port Keeps Shop Clean

Too often we hear that 3D printing is at best only a way for making prototypes before you invest in “real” manufacturing. At worst, it’s a way to make little toys for your desk or cubicle. The detractors say that 3D printing doesn’t lend itself to building practical devices, and even if you do manage to print something useful, you probably could have made it faster or better with more traditional manufacturing methods. So naturally we’re especially excited when we see a printed design that manages to buck both criticisms at once.

Not only does this magnetic dust port connector created by [Taylor Landry] have a clear practical purpose, but its design largely defies normal construction techniques. It consists of two flanges, sized for common 4″ flexible ducting, which feature embedded magnets on the faces.

This allows the two sides of the coupling to easily be connected and disconnected without relying on threads or a friction fit. Not only would threads likely get caked with sawdust, but the magnetic connection allows the coupling to release in the event somebody trips on the duct or the tool is moved.

Currently only one type of coupling is available, but [Taylor] says he’s looking at adapting the design to other tools. He also mentions that the magnets he’s currently using are a custom size he had left over from a previous project, so if you’re looking to replicate the design you might need to tweak the magnet openings. Luckily, he’s provided the STEP files so you don’t have to hack the STL.

A quick connect dust port like the one [Taylor] has come up with seems like it would be a perfect addition to the whole-shop dust collection systems we’ve covered in the past. In fact, it might not even be the only 3D printed component in the system.

Hacked Vacuum Chamber Won’t Suck a Hole in Your Budget

There’s nothing like a true hack, where something useful is concocted from bits of scrap and bargain store finds. Builds like these are much more than the sum of their parts, especially when they result in a useful tool, like this DIY vacuum chamber that’s good for all sorts of jobs.

Everything [Black Beard Projects] used to accomplish this build is readily available almost everywhere in the world, although we have to note that appliance recycling efforts and refrigerant recovery programs have made it somewhat harder to lay hands on things like the old fridge compressor used here. The big steel cooking pot is an easy thrift store find, though, and while [Black Beard] used high-quality stainless fittings and valves to plumb the chamber, pretty much any cheap fittings will do.

The one sketchy area of the build is the plexiglass sheet used for the chamber top, which seems a little on the thin side to us. You can see it flexing in the video below as vacuum is pulled; it survived, but we can see it failing catastrophically at some point. We stand ready to be reassured in the comments. Still, it’s a tidy build with a few nice details, like wiring a switch into the old start capacitor box and using car door edge protector as a gasket on the chamber.

Fridge compressor hacks are standard fare, of course, being used to make everything from air compressors to two-stroke engines. Sometimes they’re even used to keep things cool too.

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