sharpening a knife with a spark plug #machining #video demonstrates terrible knife technique on a tomato. Horrible elevator music. Then demonstrates obviously #fakenews #misinformation sharpening technique using the gap between two jam nuts on a bolt chucked up in a drill. Then demonstrates “sharpening” a different knife, evidently freshly sharpened on a grindstone, on the bottom of a ceramic mug, a technique which can work, though probably not with the movement demonstrated. ("Creative Hacker" gets killfiled!) Then a third knife, already evidently fairly sharp, finally demonstrates the supposed sparkplug technique: the plug is held in a vise to be hacksawed through the metal part, permitting the separation of the sintered sapphire insert, which apparently has an unglazed section where the metal covered it, which is used with the same ineffective movement to sharpen this third knife.
on 02024-04-05can #ultrasonic waves eat metal? #video demonstrating ultrasonic cleaning and giving an introduction to acoustics. Claims that sound pressure at a given “amplitude” is proportional to frequency, but the WP article on the absolute threshold of hearing says that 20μPa = 0.98pW/m² at 1 atm and 25°C without giving a frequency, so I’m not sure what definition of “amplitude” would make this true. Displacement, I guess? Immediately afterwards, though, he equates amplitude to loudness, so I guess he’s just wrong. Also the video has lots of worthless talking head footage. By “eat metal” apparently he means tear gold leaf apart. But he says it’s “brass foil”, thickness unspecified. I guess we can relegate "The Action Lab" to the #fakenews #misinformation category.
on 02024-04-04#manufacturing #ceramics by pit-firing in your back yard #video full of bullshit about pores in pottery opening with heat and closing when cooling, confusing grog with tempers in general, how “mineral vapors” produce different colors, etc., plus lots of useless footage of some guy talking to the camera #pseudoscience #misinformation
on 02024-04-03