Small, Quiet Air Compressor Puts 3D-Printed Parts To Best Use

When the only tool you’ve got is a hammer, every problem starts to look like a nail. Similarly, while a 3D printer is a fantastic tool to have, it can make you think it’s possible to build all the things with printed parts. Knowing when to print ’em and when to machine ’em is important, a lesson that [Diffraction Limited] has taken to heart with this semi-printed silent air compressor.

The key to this compressor’s quiet operation is a combination of its small overall size. its relatively low output, and its strategic use of plastic components, which tend to dampen vibrations. The body of the compressor and the piston arms are the largest 3D-printed parts; the design calls for keeping printed parts in compression for longer life, while the parts of the load path in tension travel through fasteners and other non-printed parts. The piston design is interesting — rather than being attached to connecting rods via wrist pins, the machined Delrin pistons are solidly attached to the piston arms. This means they have to swivel within the cylinders, which are made from short pieces of metal tubing, with piston seals designed to move up and down in grooves on the pistons to allow air to move past them. The valve bodies atop each cylinder are salvaged from another compressor.

When powered by a NEMA23-frame BLDC motor via a belt drive, the compressor is remarkably quiet; not quite silent perhaps, but still impressively smooth, and capable of 150 PSI at low speeds. And as a bonus, the split crankcase makes it easy to open up and service, or just show off how it works. We’ve seen a variety of 3D-printed compressors, from screw-type to Wankel, but this one really takes the prize for fit and finish. Continue reading “Small, Quiet Air Compressor Puts 3D-Printed Parts To Best Use”

Electrospinning Artificial Heart Valves

When you think about additive manufacturing, thoughts naturally turn to that hot-glue squirting CNC machine sitting on your bench and squeezing whatever plastic doodad you need. But 3D printing isn’t the only way to build polymer structures, as [Riley] shows us with this fascinating attempt to create electrospun heart valves.

Now, you may never have heard of electrospinning, but we’ll venture a guess that as soon as you see what it entails, you’ll have a “Why didn’t I think of that?” moment. As [Riley] explains, electrospinning uses an electric field to build structures from fine threads of liquid polymer solution — he uses polycaprolactone (PCL), a biodegradable polyester we’ve seen used in other medical applications, which he dissolves in acetone. He loads it into a syringe, attaches the positive terminal of a high-voltage power supply to the hypodermic needle, and the negative terminal to a sheet of aluminum foil. The charge turns the PCL droplets into fine threads that accumulate on the foil; once the solvent flashes off, what’s left is a gossamer layer of non-woven plastic fabric.

To explore the uses of this material, [Riley] chose to make an artificial heart valve. This required a 3D-printed framework with three prongs, painted with conductive paint. He tried a few variations on the design before settling on a two-piece armature affixed to a rotating shaft. The PCL accumulates on the form, creating a one-piece structure that can be gingerly slipped off thanks to a little silicon grease used as a release agent.

The results are pretty impressive. The structure bears a strong resemblance to an artificial tricuspid heart valve, with three delicate leaves suspended between the upright prongs. It’s just a proof of concept, of course, but it’s a great demonstration of the potential of electrospinning, as well as an eye-opening look at what else additive manufacturing has to offer.

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How A Steam Bug Once Deleted All Of Someone’s User Data

In a retrospective, [Kevin Fang] takes us back to 2015, when on the Steam for Linux issue tracker [keyvin] opened an issue to report that starting the Steam client after moving the Steam folder had just wiped all of his user data, including his backup drive mounted under /media. According to [keyvin], he moved the standard ~/.local/share/steam to a drive mounted under /media and symlinked ~/.local/share/steam to this new location on the external drive. He then tried starting Steam, which failed, before Steam crashed and tried reinstalling itself. That’s when [keyvin] realized that Steam had apparently recursively deleted everything owned by his user from the root folder.

The infamous Valve code that made Linux users sad.
The infamous Valve code that made Linux users sad.

In the issue thread, user [doofy] got hit by the same bug when trying to directly start the ~/.local/share/steam/ script with debugging enabled. He then was the first to point out the rm -rf in that script, but since this particular line is in a function only called when Steam tries to remove and reinstall itself to ‘fix’ a botched start, how did this happen? Ultimately it seems to be because of the STEAMROOT variable being set to an empty string, and another unset variable triggering the reset_steam() function, leading to the demise of all the user data.

Since then Valve has presumably fixed the issue, as no further users have filed tickets, but it’s concerning that a similar issue seems to still exist on Windows. Whether or not the original Linux issue has been fixed, it shows clearly how one should always check return values and perhaps, just maybe, never do an automated rm -rf or equivalent.

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Flipped Transformer Powers Budget-Friendly Vacuum Tube Amp

If you’ve ever wondered why something like a radio or a TV could command a hefty fraction of a family’s yearly income back in the day, a likely culprit is the collection of power transformers needed to run all those hungry, hungry tubes. Now fast-forward a half-century or more, and affordable, good-quality power transformers are still a problem, and often where modern retro projects go to die. Luckily, [Terry] at D-Lab Electronics has a few suggestions on budget-friendly transformers, and even shows off a nice three-tube audio amp using them.

The reason transformers were and still are expensive has a lot to do with materials. To build a transformer with enough oomph to run everything takes a lot of iron and copper, the latter of which is notoriously expensive these days. There’s also the problem of market demand; with most modern electronics favoring switched-mode power supplies, there’s just not a huge market for these big lunkers anymore, making for a supply and demand equation that’s not in the hobbyist’s favor.

Rather than shelling out $70 or more for something like a Hammond 269EX, [Terry]’s suggestion is to modify an isolation transformer, specifically the Triad N-68X. The transformer has a primary designed for either 120 or 230 volts, and a secondary that delivers 115 volts. Turn that around, though, and you can get 230 volts out from the typical North American mains supply — good enough for the plate supply on the little amp shown. That leaves the problem of powering the heaters for the tubes, which is usually the job of a second 6- or 12-volt winding on a power transformer. Luckily, the surplus market has a lot of little 6.3-volt transformers available on the cheap, so that shouldn’t be a problem.

We have to say that the amp [Terry] put these transformers to work in sounds pretty amazing — not a hint of hum. Good work, we say, but we hope he has a plan in case the vacuum tube shortage gets any worse.

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Building A Giant Vacuum Tube Smart Lamp

Vacuum tubes are pretty, which is why they’re often showcased externally on exquisitely-expensive home Hi-Fi hardware. But if you just want to gaze at their beauty without making any noise, why not build this vacuum tube lamp from [Noel Törjék] instead?

[Noel] got into some creative reuse with this build, with the main body consisting of a bell jar and wooden bowls. The internal structure is then created from jar lids, wire, metal sheeting, steel rods, and galvanized wire mesh. Simple modelling techniques are used to assemble the internal parts of the “valve,” including the grid and the electrodes and so on. As for light, [Noel] employed a ZigBee LED driver that he could control over his smart home setup via a Philips Hue bridge.

The final result looks like an extra-large tube. Anyone who knows what it is will spot that it’s not a real one, but they’re also exactly the audience that will appreciate it for what it is. Everyone else will probably just think you’ve taken an interest in strange art-deco replica lighthouses. It’s not the first time we’ve seen replica valves around these parts, though, and we’re sure it won’t be the last!

Home Brew Sandblaster Is A Junk Bin Delight

Opinions vary as to what actually constitutes a “complete” shop, but one thing is for sure: the more tools, the better. That doesn’t mean running out to buy a tool every time you have a need, of course. Sometimes you can throw together what you need from scrap, as with this ad hoc sandblaster. (Video, embedded below.)

Fans of junk builds — and we mean that with the highest respect — will want to pay special attention to [GARAGEUA]’s video below. It looks like pretty much everything he uses to make this sandblaster comes from the junk pile — bits of old plumbing fixtures, a blow gun that’s seen much better days, some old nuts and bolts, and even a deceased spark plug all make an appearance. That last one is perhaps the most interesting, since with some clever dissection the spark plug’s body and its ceramic insulator were used for the nozzle of the sandblaster. And best of all, no lathe was needed for this job — everything was done with a hand drill and an angle grinder. Check out the build details in the video below; you might pick up some useful tips.

We’ve featured even junkier sandblaster builds before, but this one is a clever way to save a few bucks and flex a bit on your mechanical ingenuity. If you need a sandblaster and it’s something you’re going to use again and again, by all means go out and buy one — we won’t judge. But rolling your own is cool too.

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One Coder Is Porting Portal To The Nintendo 64

When Portal came out in 2007, developers Valve chose not to release the groundbreaking title on an obsolete Nintendo console long out of production. Nobody cared at the time, of course, but [James Lambert] is here to right that wrong. Yes, he’s porting Portal to the N64.

The port, or “demake,” as [James] calls it, has been under construction for some time. The project has posed some challenges: Portal was developed for PCs that were vastly more powerful than the Nintendo 64 of 1996. Thus, initial concerns were that the console wouldn’t be able to handle the physics of the game or render the recursive portal graphics.

However, hard work has paid off. [James] has chipped away, bit by bit, making improvements to his engine all the while. The latest work has the portals rendering nicely, and the companion cube works just the way you’d expect. There’s also a visible portal gun, and the engine can even render 15 recursive layers when looking through mirrored portals. Sixteen was too much.

Of course, there’s still lots to do. There’s no player model yet, and basic animations and sound are lacking. However, the core concept is there, and watching [James] flit through the not-quite-round portals is an absolute delight. Even better, it runs smoothly even on original Nintendo hardware. It’s a feat worthy of commendation.

We had no idea what [James] had in store back when we featured his work creating real-time shadows on N64 hardware. Now we know! Video after the break.

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