@TSM: “Auto-owner, we consider this a family friendly forum and try to be cordial and use words that we’d use with out daughters”. I am with out (without) daughters, and my word use is just fine! Sorry- I couldn’t resist…
@rwee2000: A magnetized screwdriver will not harm computers or even mechanical hard drives. In fact, hard drives are more resilient to magnetism than you might think. We have a bulk tape eraser at work. It is a powerful unit, operated by line current. Physically, it is about the size of a travel iron. Out of curiosity, I took a failing laptop hard drive and tried to erase it with the bulk eraser. I triggered the eraser and the magnetic field was strong enough to cause the laptop drive to leap to the bottom of the eraser and hold there, vibrating at 60 Hz. I did this repeatedly, probably at least 5 times. Then I took the (already previously damaged) drive that had not only just been subjected to the eraser, but had also suffered the physical trauma of being repeatedly slammed into it by the magnetic field, and hooked it up to a USB cable and tried to read it.
To my surprise, I could still read the data, though a disk check yielded more errors than before.
Yes, I know the odds are very low that I’d lose data, but given where I work, a very low chance is still a chance, and personally I don’t want to spend the next two days restoring from backups, (yes it would take that long, we only had to do it once due to a hardware failure). And yes I use a anti static straps, mats, etc, even though some people where I work thinks it’s an overkill, but then again they aren’t the one’s who would get stuck restoring the data.
@rwee2000: I get what you’re saying, and I’m the IT guy who has to recover data myself, and have done so from everything from phones to servers. But in a mechanical hard drive, there’s a very powerful magnet typically not even an inch from the drive platter(s). There is also a “voice coil” actuator to move the head array, and this has a changing magnetic field, also not far from the platters. Then you have the brushless DC motor, just below, doing its thing as well. Do you think the feeble magnetic field from a screwdriver is going to affect anything, especially when just using it to remove screws near the drive, not even close to the platter, which is also shielded by the drive’s housing? I’ve been using a magnetized screwdriver for more than a decade to work on computers, with no ill effects. (just saying)
Computers is one of the caps I wear, I did not know they had powerful magnets, I’ll be busting them open for the magnet, they are a disposable item, ie it fails, I replace it. But I have a box of old drives waiting for demolition. I experimented with the magnetism on hard drives and was not able to make any fail. Any one remember the old days of parking a drive before turning off a computer?
Magnetic materials have a property called coercivity.
Basically resistance to being demagnetized.
Remember cassette tapes? There were 3 types.
Conventional ferric, later chrome and then metal particle.
Chrome and metal had better performance but needed a stronger signal (bias) from the tape head to make a recording.
The reason was higher coercivity.
The data on a hard drive, or an analog tape are tiny magnets next to each other.
As capacity goes up the magnets get smaller and smaller, and weaker.
Too small and they can demagnetize each other. The remedy is higher coercivity.
Take an old fashioned bulk tape eraser and try to erase a metal particle cassette.
It will do a poor job. Many tape decks didn’t do so well either.
Metal cassettes were avoided by those doing re-recording.
Try to erase a VHS tape. It won’t work.
Same deal with hard drives.
The ever rising capacity of hard drives is partly due to development of higher coercivity magnetic coatings.
As capacity goes up the magnets get smaller and smaller, and weaker.
I don’t think there’s ANY new technology in NON-SSD drives these days. I’ll never buy a computer without SSD.
Try to erase a VHS tape. It won't work. Same deal with hard drives.
They can be earsed. But you need a degausser. It eliminate the magnetic field. But in doing so the hard-drive is then unusable. Easier to just send it to the crusher.
“I don’t think there’s ANY new technology in NON-SSD drives these days”
What do you mean by “these days”?
Hard drive capacities have been rising for the past 30 years, partly due to improved magnetic coatings.
Your reference to SSD’s is a strawman: irrelevant to my post.
“They can be earsed (sic). But you need a degausser.”
Note I was referring to “old fashioned bulk tape erasers”.
They are degaussers, but not strong enough to demagnetize the newer high coercivity materials.
“But in doing so the hard-drive is then unusable. Easier to just send it to the crusher.”
What’s the point of this statement??
I DID NOT suggest anyone try to fix their hard drive by degaussing it.
@oblivion
I hear you, but when you have to stand in front of non-computer people and explain that said magnetized screwdriver couldn’t have caused the problem, and someone says, “Yea but my buddy say a magnet can erase a hard drive.” or that a magnet erased their floppy, etc. I just find it better not to use anything magnetic, hence the glue stick, that way no explaining to do.
If anyone understands magnetism explain this one to me. Pulled the magnets from a hard drive, and yes they are incredibally strong. I have made a few attempts a making a perpetual motion machine using magnets, but the pull and push results in no gain of energy. The magnets I pulled from the hard drive exhibit a unique property.
The magnet is very powerful on the magnet side, but undetectable on the side opposite the backing plate. so new experiments in eternal motion machine, but why does the backing plate eliminate magnetic attraction?
There’s a type of specialized metal called “mu metal” or something like that that has the ability to shield stuff from magnetic fields. Maybe the backing plate is made of that, presumably to reduce the chance the magnet’s magnetic field interferes with reading and writing the data to the disk surface.
Just curious, when you took the hard drive apart, could you tell what the magnet is for? Is it part of a mechanism that moves, like something for the head movement mechanism? Or the motor drive? Or does it look like it is providing a magnetic bias field directed towards the disc surface?
Perpetual motion … you’ve probably already seen one, but there’s something like that you can buy for a desk conversation piece. It appears at first glance to be a never-ending swinging pendulum with a metal bob at the end. But, alas, inside it has a small battery, I believe the battery powers a sync’d electromagnet in the base to give the bob a little shove each time to keep it going. But it is still a pretty cool idea.
“Perpetual motion” is a never-ending hobby…
Two magnets attracting or repelling behave very much like a spring.
Energy can be stored and released, but not created (required for perpetual motion).
Magnetic force can seem mysterious, leading people to think there’s extra energy to be had.
Hey, I think one of the great ideas from this thread got expropriated … lol … I noticed the other day that in the current issue of Family Handyman there’s a reader idea published that says in order to easily magnetize a screwdriver, just stick a rare earth magnet on the shaft.