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

On 10/31/2010 08:57 PM, Steve B wrote:
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?

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.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On 10/31/2010 9:14 PM, Tim Wescott wrote:
On 10/31/2010 08:57 PM, Steve B wrote:
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?

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.



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

On Sun, 31 Oct 2010 21:14:53 -0700, Tim Wescott
wrote:

On 10/31/2010 08:57 PM, Steve B wrote:
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?

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.


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,

Gunner Asch fired this volley in
:



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.....


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

On Mon, 01 Nov 2010 06:34:33 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Gunner Asch fired this volley in
:



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.....


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

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 .....G

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

Ask me how I know......sigh


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,

On 11/01/2010 09:12 AM, Gunner Asch wrote:
On Mon, 01 Nov 2010 06:34:33 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Gunner fired this volley in
:



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.....


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

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 .....G

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

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

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

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Mon, 01 Nov 2010 09:27:22 -0700, Tim Wescott
wrote:

On 11/01/2010 09:12 AM, Gunner Asch wrote:
On Mon, 01 Nov 2010 06:34:33 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Gunner fired this volley in
:



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.....


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

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 .....G

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

ROFLMAO!! Excellent!!!

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

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

Very well said!!

VBG


"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,

On Oct 31, 9:57*pm, "Steve B" wrote:
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

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

On Nov 1, 5:03*pm, wrote:
On Oct 31, 9:57*pm, "Steve B" wrote:

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

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

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.

On Mon, 01 Nov 2010 19:53:08 -0400, Wes wrote:
Gunner Asch wrote:

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

Very well said!!

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.

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

Thanks!
Rich

Tim Wescott wrote:

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.

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

Gunner Asch wrote:

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

Very well said!!

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

fired this volley in news:7f6e82db-4e07-43b2-800e-
:

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



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

rangerssuck fired this volley in news:cf96a2fc-
:

My kitchen knives, however, live in a drawer that has
an HDPE bar with slots to hold the knoves upright.

Hopefully, edge-up.

LLoyd

On Mon, 01 Nov 2010 19:56:24 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

rangerssuck fired this volley in news:cf96a2fc-
:

My kitchen knives, however, live in a drawer that has
an HDPE bar with slots to hold the knoves upright.

Hopefully, edge-up.

LLoyd

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,