Torturing An Instrumented Dive Watch, For Science

The Internet is a wild and wooly place where people can spout off about anything with impunity. If you sound like you know what you’re talking about and throw around a few bits of the appropriate jargon, chances are good that somebody out there will believe whatever you’re selling.

Case in point: those that purport that watches rated for 300-meter dives will leak if you wiggle them around too much in the shower. Seems preposterous, but rather than just dismiss the claim, [Kristopher Marciniak] chose to disprove it with a tiny wireless pressure sensor stuffed into a dive watch case. The idea occurred to him when his gaze fell across an ESP-01 module next to a watch on his bench. Figuring the two needed to get together, he ordered a BMP280 pressure sensor board, tiny enough itself to fit anywhere. Teamed up with a small LiPo pack, everything was stuffed into an Invicta dive watch case. A little code was added to log the temperature and pressure and transmit the results over WiFi, and [Kristopher] was off to torture test his setup.

The first interesting result is how exquisitely sensitive the sensor is, and how much a small change in temperature can affect the pressure inside the case. The watch took a simulated dive to 70 meters in a pressure vessel, which only increased the internal pressure marginally, and took a skin-flaying shower with a 2300-PSI (16 MPa) pressure washer, also with minimal impact. The video below shows the results, but the take-home message is that a dive watch that leaks in the shower isn’t much of a dive watch.

Hats off to [Kristopher] for doing the work here. We always love citizen science efforts such as this, whether it’s hardware-free radio astronomy or sampling whale snot with a drone.

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Crown Earns You The Title King Of The Junkyard

crown-king-of-the-junkyard

[Greg Shikhman] wanted to use the school tools one more time before graduation. After hitting up some local motorcycle shops around town for parts he fashioned this crown for himself.

He didn’t pay ‘the iron price‘ as the motorcycle roller chain is waste material anyway. Chains do wear out and these were left over after being replaced with new ones. He first cleaned them up with a bit of WD-40 solvent, xylene, and soapy water to cut through the grime. There was also a layer of black oxide which normally keeps them from rusting which he peeled off with a dunk in some hydrochloric acid.

Chains are flexible and this would have made for a disheveled looking crown. The fix involved using an aluminum form the size of his head to keep the crown in round while he did his TIG welding. A double row of polished steel ball bearings take the place of jewels. As if the ten-pounder wasn’t painful enough he added four rings of bicycle chain as accents which he admits makes the thing unwearable because they dig into his noggin. We still don’t think that’s a good enough excuse to post about the project and not include an image of him wearing the thing during the junkyard coronation.

It would be fun to see a follow-up king-ring with similar LED features as that engagement ring but using this heavy-metal design style.