Neodymium or rare earth magnets are available everywhere now. They come in various shapes and sizes.....but don't let the size fool you. They are deceptively strong. You may have watched videos or read warnings about the power of these things in various places. A lot of us find that some of the ridiculous warnings out there today are to protect the very weak (both body and mind). I'm here to tell you, pay attention to the ones on these things.
I ordered a few 1" x 1" cylindrical ones for a couple of digging tools I'm making for metal detecting this summer. As soon as I opened the package and tried to pull them apart, I knew that they were not the magnets I'd ripped out of giant speakers as a kid. Hey...I don't really have to worry about these things though, right ? Man....I'm a tough industrial mechanic with 30 years under his belt. My hands are stronger, and just plane tougher than most.....right ?
I was able to take them apart easy enough due to the plastic spacers the company put in between them. While looking them over...about a whole 20 seconds worth of looking them over, old dumb dumb got sloppy.If you were standing 10 feet from me, you probably could have seen the stupid starting to leak out of my ears because I was overflowing with it. I got 2 of them too close together. Sure enough, I got a chunk of skin on one of my fingers pinched in there. It wasn't anything serious, but it did get me bleeding and it hurt like hell. I have every faith in the world that if you put 2 of these things on a counter, 16" inches apart and you got a finger between them as they slammed together, you're going to have a lot of blood, and more than likely a horribly crushed and broken bone. The real problem then is, how do you get them apart to get your finger out ?
Guys...heed the warnings. The ones I bought are about the size of a dozen quarters stacked together. The largest ones I've seen for sale are 2" x 6" disks. That is just insane. The pull force is rated at over half a ton if memory serves...and that's not 2 magnets pulling together....it's one, pulling on iron. I read one place (might have been fiction, but I have no reason not to believe it) that if you get your hand slammed in between 2 bigger magnets, like 2"x2" cubes, it very well can result in the docs having to amputate your hand. There are 2 issues...first is the initial crush damage that's done. If that wasn't bad enough, remember...these things pull harder, the closer they get together. A LOT, LOT, LOT, LOT, LOT HARDER. When your now munched hand is only separating them by half an inch, by the time you get to the hospital, that distance will have been crushed down a lot more. It's the pinch point that keeps on giving. The problem now is, there's no way for the emergency room guys to get them apart. There's no off switch on these things. Anyway...without getting too gruesome, you get the idea.
In closing...if you're handling these things, wear a pair of decent leather gloves, and ALWAYS be aware of where they are if there's 2 of them. The two that got me will interact with each other when they're 16" apart, and they're not that big. That's with one on the floor, and me hovering the other one above it. The distance on a flat surface where they both could easily roll is no doubt even more than that. When I got pinched, they were already touching on one corner, and then snapped together, flat side to flat side. I don't want to think of what would happen if they were 16" apart on a flat surface, my finger or hand was in there, and they started to fly together. Oh...and one last thing. Don't think that your super human reflexes are going to save you. Once they start moving, the acceleration in unbelievable. These are not the old ceramic magnets we played with as kids that we thought were crazy strong....not even close. It's like comparing a Model A Ford to a modern dragster. Please....learn from my pain.