A 1971 Thermos compliments this mid-century corner of my office.

The Incredible Tech Of The Vacuum-Seal Flask

October 21, 2021 by Kristina Panos 38 Comments

I recently started using a 50-year-old vacuum-seal flask that belonged to my Grandpa so that I don’t have to leave the dungeon as often to procure more caffeine. Besides looking totally awesome on my side desk, this thing still works like new, at least as far as I can tell — it’s older than I am.

Sir James Dewar's original vacuum-seal flask. — Sir James Dewar’s original vacuum-seal flask. Image via the Royal Institute

Of course this got me to wondering how exactly vacuum-seal flasks, better known in household circles as Thermoses work, and how they were invented. The vacuum-seal flask is surprisingly old technology. It was first invented by Scottish chemist Sir James Dewar and presented to the Royal Institute in 1892. Six years later, he would be the first person to liquefy hydrogen and is considered a founding father of cryogenics. Continue reading “The Incredible Tech Of The Vacuum-Seal Flask” →

DIY Ram Pump Obeys The Laws Of Physics

June 7, 2017 by Dan Maloney 45 Comments

Despite the claims of “free energy” on the title of the video below, this is not yet another wacky perpetual motion story. We here at Hackaday fully support the laws of thermodynamics, and we think you should too. But you have to admit that a pump that works without any apparent energy inputs looks kind of shady at first glance.

The apparatus in question is a ram pump, a technology dating back all the way to the 18th century. The version that [Junkyard – Origin of Creativity] built uses commonly available materials like PVC pipes and fittings. About the only things on the BOM that might be hard to scratch up are the brass check valves, which should probably be flap valves rather than the easier to find spring valves. And the only custom part is an adapter to thread the plastic soda bottle that’s used as an air chamber to the PVC, which a 3D printer could take care of if you choose not to hack a bottle cap like [Junkyard] did. The video below shows the impressive lift achieved just by tapping the kinetic energy of the incoming flow.

There, the Second Law of Thermodynamics remains inviolate. But if you still think you can get something for nothing, check out our roundup of perpetual motion and Overunity quackery.

Continue reading “DIY Ram Pump Obeys The Laws Of Physics” →

Ask Hackaday: Can The Lix 3D Printing Pen Actually Work?

May 3, 2014 by Brian Benchoff 281 Comments

Introducing Lix, the world’s smallest 3D printing pen that allows you to draw plastic structures in 3D. It’s only been on Kickstarter for a few days now, and already it has garnered close to a million dollars in pledges. An astonishing achievement, especially considering we can prove – with math and physics – that it doesn’t work as advertised. However, we’re wondering if it could work at all, so we’re asking the Hackaday community.

The device is powered through a USB 3 port. In the video, the Lix team is using a MacBook Pro. This has a USB port capable of delivering 900 mA at 5 Volts, or 4.5 Watts. Another 3D printing pen, the 3Doodler, uses a 2A, 12V power adapter, equal to 24 Watts. Considering the 3Doodler works, and they both do the same basic thing, there’s something extremely odd going on here.

Just as a comparison, here’s a wirewound resistor commonly found in the heating element or ‘hot end’ of a 3D printer. It’s a 6.8 Ohm resistor powered at 12 Volts. That’s 21 Watts. Here’s a heater cartridge, also found in quite a few hot ends. It sucks down 40 Watts. Once again, the Lix Kickstarter clearly shows the pen extruding filament using only 4.5 Watts of power. Something is really, really fishy here.

Intuition doesn’t hold a candle to math, so let’s figure out exactly why it won’t work.

Continue reading “Ask Hackaday: Can The Lix 3D Printing Pen Actually Work?” →