Magnetic Screws?

[Russ Filtz]

Anyone try this? Seems gimmicky, but for the right application could be cool.

https://i.imgur.com/QtVB1cK.gifv

[Jim Becker]

Certainly an interesting concept and while not something likely to be practical in a big way, I have no doubt there are applications where it could be just the thing...

[Bill Dufour]

I bet his watch is trash by now. Do microwave ovens generate magnetic fields? I do not think speakers are strong enough to open the joint.
My father worked at Lawrence Berkeley Lab around a big particle accelerator with huge magnetic forces. Strong magnets do some weird stuff. He carried a 6" steel rule in his pocket. It was magnetized just from being around the machine when the power was off. He said welders had a hard time because the arc would not go straight with tons of magnetized iron to draw it off track. They had to use Copper hammers because steel hammers would not go in a straight line etc.
Bill

[Rich Engelhardt]

Made by Invis/Lamello

(& yes, hold onto the chair when you check the prices)

Those and a couple other systems have been out for quite a few years.

[Andrew Seemann]

Like Bill said, those super magnets do weird things. I got a "back stage" tour of the U of MN nuclear physics lab about 25 years ago. When we got to the super magnet, they guy had us take a 1/4 inch piece of plate aluminum 6 inches wide and about 2 feet long, and wave it in front of the magnet. It was like moving it in water. Even though the aluminum isn't magnetic per se, it is affected by the magnetic eddies or something like that. Kinda neat, and kinda frightening at the same time.

[Bill Dufour]

Reminds me of watching how slow they were when the redid the roof on the Bevatron. A job that should have been done in a few weeks took over a year because they could not be on the roof if the machine was running.
They were running almost 24/7 and the shielding was only on the sides. nothing to protect workers on the roof from the radiation. Probably far enough from the magnets that the residual magnetism would not be a big issue. They tore it down within the last ten years. i believe pretty much all of it had to buried in Nevada?
Bill

[John K Jordan]

... When we got to the super magnet, they guy had us take a 1/4 inch piece of plate aluminum 6 inches wide and about 2 feet long, and wave it in front of the magnet. It was like moving it in water. Even though the aluminum isn't magnetic per se, it is affected by the magnetic eddies or something like that. Kinda neat, and kinda frightening at the same time.

This effect is due to eddy currents induced in the non-ferromagnetic metal, described by Lenz's law. The eddy currents create their own magnetic field in the aluminum which oppose the external field. You can find youtube videos demonstrating it. Or just drop a strong magnet through an aluminum or copper tube - it will fall slowly.

There are lots of practical applications for eddy currents, including non-destructive testing, in vending machines, for braking. I have a precision laboratory balance scale that uses this principle to dampen and stop the balance swing quickly.

JKJ

[Bill Dufour]

Eddy currents are how speedometers worked. The cable spun a magnet inside the gauge. The needle was attached to an aluminum cup which sat over the spinning magnet. The faster the magnet spun the farther the cup rotated and moved the needle attached to the cup. I believe there was a spring to add resistance force. Modern gauges are stepper motors driven by a computer digital signal.
Bill

PS: was the magnet turned on or was it just residual forces?

[Jerome Stanek]

Back in the 80's we put a test room for Picker for a new type of scanner called a MRI and had to use aluminum screws and floor pedestals for their computer floor.

[Andrew Seemann]

Going by memory (hazy at best), it was a permanent magnet about 6 inches in diameter and a few feet long, although I am not certain. I was more focused on the effects than the setup (and a little worried about what else it may have been doing to us physiologically)