Electromagnets

Electromagnets

Post by bob » Wed, 21 Apr 1999 04:00:00



Hello All,

Yes, I know this is not rocket related but I need to make a big
electromagnet to pick up nails at our family cabin after our big
remodeling project these past months.  Who better to ask than a bunch of
wacky rocketeers, right?  

Lots of kids will be running around over the spring and summer so I'd
like to be safe before we turn them loose to find the nails in their own
special way.  I was thinking of something like a bar or loop wound to
make a coil and energizing it through a gfi protected 110 circuit.  A
long extension cord and I'd be all set. (this is beginning to sound like
a "Hey, watch this!" kind of thing)  I could also use a big transformer
(12 volts) or a couple of car batteries if it's nix on the house current
power supply.  Any ideas?

--
Bob
http://www.fortunepaint.com/whozat.htm for WhoZat? Rocketeer Register
http://www.fortunepaint.com/rockets.htm for all the other stuff

 
 
 

Electromagnets

Post by Vamidpo » Thu, 22 Apr 1999 04:00:00


Bob:
It's not an electromagnet, but many large loudspeakers have a very strong
permanent magnet inside the driver coils.  Or, some marine places have
extremely strong "U" magnets for use in "fishing" for lost outboard motors and
such.  Just a thought.

Chuck Barndt
The Launch Pad
http://www.the-launch-pad.com

 
 
 

Electromagnets

Post by Ted Cochr » Thu, 22 Apr 1999 04:00:00



Quote:

>Hello All,

>Yes, I know this is not rocket related but I need to make a big
>electromagnet to pick up nails at our family cabin after our big
>remodeling project these past months.  Who better to ask than a bunch of
>wacky rocketeers, right?  
>...
> Any ideas?

They make a tool for this, it's about 3' wide, on wheels, and is used to
roll around lawns after roofing jobs. You can rent them pretty
inexpensively, and save the solder and wire for your next launch
controller....

--tc

My opinions only.

 
 
 

Electromagnets

Post by DWar » Thu, 22 Apr 1999 04:00:00



Quote:
>Hello All,

>I was thinking of something like a bar or loop wound to
>make a coil and energizing it through a gfi protected 110 circuit.  A
>long extension cord and I'd be all set. (this is beginning to sound like
>a "Hey, watch this!" kind of thing)  I could also use a big transformer
>(12 volts) or a couple of car batteries if it's nix on the house current
>power supply.  Any ideas?

You might be able to rent a device like that from your local contractor tool
rental place - roofers occasionally use an electromagnet & battery on a cart
to pick up their mess (but not at our apartment! ~sigh~)

If that's not available, I believe both Edmond Scientific and American
Surplus Supply carry prebuilt 12 volt electromagnets that should do the job.
Failing that, you could just purchase one of those treasure hunting metal
detectors and a garden trowel and remove the nails manually.

-Dave

 
 
 

Electromagnets

Post by The Silent Observe » Thu, 22 Apr 1999 04:00:00


Quote:

> Hello All,

> Yes, I know this is not rocket related but I need to make a big
> electromagnet to pick up nails at our family cabin after our big
> remodeling project these past months.  Who better to ask than a bunch of
> wacky rocketeers, right?

> Lots of kids will be running around over the spring and summer so I'd
> like to be safe before we turn them loose to find the nails in their own
> special way.  I was thinking of something like a bar or loop wound to
> make a coil and energizing it through a gfi protected 110 circuit.  A
> long extension cord and I'd be all set. (this is beginning to sound like
> a "Hey, watch this!" kind of thing)  I could also use a big transformer
> (12 volts) or a couple of car batteries if it's nix on the house current
> power supply.  Any ideas?

You've seen, I suspect, at least on film, those large electromagnets
that are mounted on cranes to lift car hulks into the crusher (or used
to be -- they seem to mostly use claws now).

Those can lift tonnes.

They run on the equivalent of a couple flashlight batteries.

The strength of the magnet is determined by the product of the number of
turns and the current in the coil.  If you keep the current low enough
to avoid burning the thing up (which I watched my dad do with a coil
connected to a car battery when I was about twelve, trying to
remagnetize a really cheap horseshoe magnet needed for a demonstration),
you'll need a lot of wire, and even then you don't need much voltage to
push the current.

For a homemade version, start with a whole spool of "bell wire" (which
you can buy at Radio Shack) -- around 50 m long, with lacquer insulation
to keep the coil compact.  Measure the resistance, and then calculate
the current (I = V/R) and power dissipation (P = V^2/R) working from a
single flashlight battery.  I think you'll be amazed.  Now, if you wind
all that wire onto a compact iron core (like one of those nails, or a
machine***of appropriate length) you'll get the kind of magnet you
want -- assuming it doesn't melt down.

Except that it'll take you well into the '***s (the twenty-***s, that
is) to clean up a yard with a magnet made from a nail with a bunch of
wire wrapped on...  B(

Best to rent the commercially made version...

--
 WARNING!!  This area has been designated an official DOPE FREE ZONE!!

      If you're going to be a dope, please do it somewhere else!

Donald Qualls, aka The Silent Observer           NAR # 70141-SR Insured
Rocket Pages             http://www.FoundCollection.com/

Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.

 
 
 

Electromagnets

Post by bob » Thu, 22 Apr 1999 04:00:00


Oh well,

Just thought it would be fun.  I imagined myself sweeping the grounds
with some nifty/kludgy device similar to a wire wrapped dust mop hooked
to a long orange extension cord picking up nails.

HmmmmMMMMmmmmMMMMMMMMmmmm as I sweep it back and forth over the dirt,
tik-tak-tak-tic-tic-tak-tac as the nails smack into the head of the
device, kill the power and watch all the nails drop into a bucket.
Maybe I'll skip that and just build a big Tesla coil, charge the area
and watch all the nails stand at attention waiting to be picked up. : )

Thanks so much for your help, I'll probably go by an auto stereo
installer and scrounge up a bunch of old speakers out of their trash and
use them attached to a pushbroom or something.

--
Bob
http://www.fortunepaint.com/whozat.htm for WhoZat? Rocketeer Register
http://www.fortunepaint.com/rockets.htm for all the other stuff

 
 
 

Electromagnets

Post by terry swif » Thu, 22 Apr 1999 04:00:00


Bob,
Go to

 http://scientifics.edsci.com/scientifics/index.cfm

search for magnet, then go to page 6 for large magnet. They advertise it for

 
 
 

Electromagnets

Post by Mike Bellin » Fri, 23 Apr 1999 04:00:00


Quote:

> I was thinking of something like a bar or loop wound to
> make a coil and energizing it through a gfi protected 110 circuit.  A
> long extension cord and I'd be all set.

I don't know if this would work. The current (AC) would be changing
directions every 17 milliseconds so to be attracted the nails (assuming
they have iron in them) would have to change field directions likewise.
There's some property name to how fast a magnetic material can re-orient
but I forget what it is called. My bet is the nails would just sit there
because the magnetic domains in the iron would just become scrambled and
have no net field. I think the suggestions of using a honkin' big magnet
(as found in speakers woofers) are the best. If not making an
electro-magnet using DC current (like from a battery) would also work.

Good luck! Let me know if I am wrong!

Cheers,
Mike

 
 
 

Electromagnets

Post by M&M Campbel » Sat, 24 Apr 1999 04:00:00


I think it would be easier and cheeper to rent a metal detector

Ken Johnson
                                                                   Keep it
fun, Keep it safe

 
 
 

Electromagnets

Post by Aidan Samue » Mon, 26 Apr 1999 04:00:00


I know this may sound stupid, but how about using a dustpan & brush?

Aidan

---
Reverse the order of words to create my e-mail address.
---


Quote:
>Hello All,

>Yes, I know this is not rocket related but I need to make a big
>electromagnet to pick up nails at our family cabin after our big
>remodeling project these past months.  Who better to ask than a bunch of
>wacky rocketeers, right?

>Lots of kids will be running around over the spring and summer so I'd
>like to be safe before we turn them loose to find the nails in their own
>special way.  I was thinking of something like a bar or loop wound to
>make a coil and energizing it through a gfi protected 110 circuit.  A
>long extension cord and I'd be all set. (this is beginning to sound like
>a "Hey, watch this!" kind of thing)  I could also use a big transformer
>(12 volts) or a couple of car batteries if it's nix on the house current
>power supply.  Any ideas?

>--
>Bob
>http://www.fortunepaint.com/whozat.htm for WhoZat? Rocketeer Register
>http://www.fortunepaint.com/rockets.htm for all the other stuff

 
 
 

Electromagnets

Post by bob » Mon, 26 Apr 1999 04:00:00


Quote:

> I know this may sound stupid, but how about using a dustpan & brush?

> Aidan

Hey Aidan,

Doesn't sound stupid to me! A very effective way to get rid of nails on
all the paved surfaces which we have done.  My situation is a bit
different as a lot of the nails have been tromped into the dirt around
the perimeter of the cabin.  These might be hiding just below the
surface waiting for some little footprints to find them.

Kids hunting for nails would work as well:
I can remember being a kid and getting a nickel for each nail we picked
up after my father finished one construction project or another.  He
started getting suspicious (and going broke) when we learned where there
were lots of nails all in one place, the junk wood s***pile, so this
disappeared after he caught us yanking nails out of the wood stacked
there. : )

Thanks for the suggestion.

Bob

http://www.FoundCollection.com/
http://www.FoundCollection.com/