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More magnet perving

Smelly

By Smelly
in Boat Equipment

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Bagpuss Contributor

Bagpuss

Posted
Posted
very thin Neo magnets are not very strong but get a sensible thickness and they get very powerful...

 

I've got two large recovery magnets, which I made myself, which will crush the bones in your hand if you get it between them while they are attracting each other :lol:

 

I can make these to special order for anyone interested :lol:

 

all my magnets use Neodymium cores, and they are very powerful.

 

I would be reluctant to use very small ones close to a fire because they have a maximum operating temperature of 80'C above which the magnetism is lost almost completely, permanently.

 

Smelly asked me to reply as he is 'doing stuff' with the hearth.

 

Apparently, the magnets will be inside a 100mm cube of calcium silicate, will this be likely to reach a temperature of 80 or above? If so, broke biscuits as Smelly says.

 

B

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Nickhlx Veteran

Nickhlx

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.....snip....

 

I would be reluctant to use very small ones close to a fire because they have a maximum operating temperature of 80'C above which the magnetism is lost almost completely, permanently.

 

Surely not "permanently" ?

 

My (all?) Weller soldering iron's bit has a magnet on the inner end of it, and as this rises and falls in temp, its magnetism comes and goes, switching the thermostat, and thus holding the bit temp at the desired value. At least that's how I thought it works - if not I'd like to know...

 

Nick

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RLWP Veteran II

RLWP

Posted
Posted
Surely not "permanently" ?

 

My (all?) Weller soldering iron's bit has a magnet on the inner end of it, and as this rises and falls in temp, its magnetism comes and goes, switching the thermostat, and thus holding the bit temp at the desired value. At least that's how I thought it works - if not I'd like to know...

 

Nick

 

No, not permanently, and your understanding is correct.

 

Richard

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WotEver Veteran II

WotEverDonate to Canal World

Posted
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Surely not "permanently" ?

Actually, yes, permanently. But it will only be permanent at temps much higher than was suggested.

 

Google finds loads references to this phenomenon of neodymium magnets and this site for example states

...they will however, begin to lose strength if they are heated above their maximum operating temperature, which is 176°F (80°C) for standard N grades. They will completely lose their magnetization if heated above their Curie temperature, which is 590°F (310°C) for standard N grades.

 

Tony

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Grace and Favour Veteran II

Grace and Favour

Posted
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Talking of magnets, does anyone know where to get electromagnets which can be used in water as I would like a recovery magnet but scared of the things I may raise in Bristol Floating Harbour ( ie ex ww2 stuff !)

 

Well - - if one's cautious of (possibly) detonating bang n boom type things - -

 

Don't go near them with magnets of any description

 

Magnetic fields can have rather quick effects upon some types of detonator

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RLWP Veteran II

RLWP

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How will I know its a boom and bang and not my friends outboard till it breaks the surface ! Hopefully in one peice!

 

Oh, if it's got a magnetic fuse, you'll know long before it reaches the surface.

 

Richard

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