Rare earth magnet question

• posted

I want to make a knife bar out of rare earth magnets to hold my kitchen knives. If I hold the surface of the knives off just a tad, can I avoid the scratching that would be produced with the knives touching metal to metal? Or will there be enough magnetic attraction if I use thicker magnets to suck them up against a oak or plastic substrate that would be sufficient to keep them in place, and a few thousandths of airspace between?

Or lastly, to apply a thin plastic face onto the magnet so that it never touches metal to metal?

Steve

• posted

If you get some 1/2 inch wide rare earth magnets, manage to glue them up in a continuous bar without putting an eye out from flying shards, put a thin piece of teflon tape over them and stick a knife on -- you'll be grunting and looking for a nice bronze crowbar to get your knife un-stuck.

Use big enough magnets (1/2 or 1 inch wide, 1/4" thick) and you can probably bury them under 1/16" or even 1/8" of veneer. Experiment first

-- those things are damn strong.

I remember playing with half of a linear force motor at an old place of employment one day. It used big square rare earth magnets -- something like 1/4" thick by 1.5" on a side, glued to a carrier. They came stuck to a piece of sheet steel, taped to a regular old piece of corrugated cardboard. The sheet steel was to keep them from whapping into anything _else_ magnetic, the cardboard was to space them away from the steel enough that a human being could pull them off the steel.

Personally, I'd check and see if Radio Shack still sells those big rectangular ceramic magnets. They're plenty strong, but not as over the top as rare earth magnets.

• posted

aaah, the usual way to do this is to use an equation - if it is hard, look at the equation for attraction between cylindrical magnets on wikipedia

• posted

A further note..be sure all of your knives will stick to a magnet. Ive got some stainless ones in the kitchen that are non magnetic.....

"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,

• posted

Gunner Asch fired this volley in news: snipped-for-privacy@4ax.com:

But even most "non-magnetic" stainless alloys are weakly magnetic.

I've got some 1/2" thick by 2" diameter REMs that will pin a piece of #3xx SS like a mouse in a trap.

LLoyd

• posted

Weakly magnetic..yes. But if the knife falls off when you slam the reefer door across the kitchen.....

And yes..you can use very strong magnets to hold most of them. And then you put a nice flat sided carbon steel knife on the magnet...and have to use a portapower to pull it back off .....

I wasnt critizing magnets in the knife rack...just giving folks a heads up that not all of them may stick properly.

Gunner

"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,

• posted

And then use another portapower to get the first portapower off the rack. Hence the bronze crowbar...

Any metal will stick to any magnet just fine. Hand me that bottle of superglue and I'll show you how.

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ROFLMAO!! Excellent!!!

Very well said!!

"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,

• posted

This is one of those times when I gotta ask "why"? There are plenty of magnetic knife racks in the hardware stores, pick one and be happy! By the time you get it all set up, it's going to run you a hell of a lot more than the purchased unit. You're reinventing the wheel. Ceramic magnets would be the ones to use here, the factory jobbies sandwich a line of them between steel pole pieces. You DO eventually want to remove the knives, after all. The REMs I use for woodworking tasks have a nickel plating on them, this eventually gets worn and the magnet starts to corrode, would be even more likely in a humid kitchen. NOT the item for the job.

Stan

• posted

Ikea has a good one, cheap. I have them all over my shop to hold various tools. My kitchen knives, however, live in a drawer that has an HDPE bar with slots to hold the knoves upright.

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magnets superglued

Well, are you man enough to do the experiment and report on it? Preferably with video? >:->

Thanks! Rich

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Those neodymium magnets are so cool. I recieved a sample pack with an order. Little bitty things only 1/16Lx1/8D. Those things hold pictures to fridge, stamped buttons the ones you get at Names and whatever to the fridge.

1/2"D might just hold your axe.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

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I wonder what kind of velocity one would get with a say 1"Dx1"L pair of magnets superglued NN or SS with superglue (vise needed) and then placed in a dish of acetone to act as a release agent?

Warning, do not stand in line with the magnets.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

• posted

I want to make a knife bar out of rare earth magnets to hold my kitchen knives. If I hold the surface of the knives off just a tad, can I avoid the scratching that would be produced with the knives touching metal to metal? Or will there be enough magnetic attraction if I use thicker magnets to suck them up against a oak or plastic substrate that would be sufficient to keep them in place, and a few thousandths of airspace between?

Or lastly, to apply a thin plastic face onto the magnet so that it never touches metal to metal?

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My steel pieces weighing 250 g are suspended in the electrolyte by a 0.006" brass strap which is pinned to the exposed steel areas by small magnets. Two

3/8" x 5/64" disk magnets will hold the piece comfortably. They also work through brass four times that thickness.

A single piece will hold barely if positioned right. I do not think you should have any problems.

-- Michael Koblic, Campbell River, BC

• posted

snipped-for-privacy@prolynx.com fired this volley in news:7f6e82db-4e07-43b2-800e- snipped-for-privacy@s5g2000yqm.googlegroups.com:

You obviously do not respect your knives. I would never (EVER!) allow one of mine to scrape across a stupidly-placed piece of steel not intended to hone the edge -- not even another knife.

The REMs should (as should _all_ magnetic holders) be "clothed" in a soft, non-marring plastic. The corrosion of the nickel should not be an issue.

LLoyd

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Hopefully, edge-up.

LLoyd

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Took me forever to get that tidbit through my wifes thick skull.

She said..."it doesnt look right!"

And I replied.."neither does hacking away at the meat with a large butterknife"

She finally got the idea..though it offends her sense of "kitchen beauty"

We btw..use knife blocks

Gunner

"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,

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