# Where to find a large thick copper pipe & like sized Magnets?



## gython (Feb 5, 2014)

Hello, I'm trying to buy a thick large copper pipe (6-8" in length) and some magnets to teach a school science project: 

http://truthseekerdaily.com/2014/01...gnet-is-dropped-through-a-copper-pipe-wvideo/

Do you know where to find these items? I'm In Los Angeles. Thanks for the help!!!


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## BaronJ (Feb 5, 2014)

gython said:


> Hello, I'm trying to buy a thick large copper pipe (6-8" in length) and some magnets to teach a school science project:
> 
> http://truthseekerdaily.com/2014/01...gnet-is-dropped-through-a-copper-pipe-wvideo/
> 
> Do you know where to find these items? I'm In Los Angeles. Thanks for the help!!!



I would hunt down some scrap hard disk drives and salvage the magnets from them.  The older and bigger the better.  If you can get your hands on any 5" SCSI ones, the magnets in those are huge by comparison with the ones in 3.5" drives.  Don't waste your efforts on 2.5" laptop drives.  The magnets in those are tiny and aren't worth bothering with.

For a teaching demonstration a pair of magnets, again salvaged from a HDD, they are held apart in the drive.  Drop a copper coin through between the magnets.

This is also an illustration of one of the ways a coin sorting machine works.


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## GailInNM (Feb 5, 2014)

A very good demonstration can be done with much smaller magnets and either copper water pipe or aluminun tubing.

I have used these magnets and some times the slightly less expensive N42 magnets  in pipe/tubing with about 5/8 inside diameter and 12 to 18 inches long.  The N52 does work better.  I have given several away and always keep one in the shop to entertain visitors.

http://www.kjmagnetics.com/proddetail.asp?prod=D88-N52

Gail in NM


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## barnesrickw (Feb 5, 2014)

I did that while teaching science.  Rare-earth (neodymium) disk magnet works best.  Thick wall copper tubing a little larger the diameter as the magnet.  First time I saw it, it blew my mind, it's a hit at parties, but it looks strange to come to a party carrying magnets and copper pipe. 


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## barnesrickw (Feb 5, 2014)

Sorry about the incomprehensible post.  Watching TV while posting is potentially hazardous. 


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## BaronJ (Feb 5, 2014)

barnesrickw said:


> I did that while teaching science.  Rare-earth (neodymium) disk magnet works best.  Thick wall copper tubing a little larger the diameter as the magnet.  First time I saw it, it blew my mind, it's a hit at parties, but it looks strange to come to a party carrying magnets and copper pipe.
> 
> 
> Sent from my iPad using Model Engines



Hi Rick,
Its notable that the effect has been known about for more than a century and a half and has been in commercial use for almost as long.   "The first person to observe current eddies was François Arago (17861853), the 25th Prime Minister of France."  also  "The first use of eddy current for non-destructive testing occurred in 1879 when David E. Hughes used the principles to conduct metallurgical sorting tests."  Still in use today in vending machines, parking meters etc.

Where have you seen these before ? 
<http://en.wikipedia.org/wiki/File:Hydro_quebec_meter.JPG>

See:   <http://en.wikipedia.org/wiki/Eddy_current>


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## gython (Feb 6, 2014)

Thanks for the help guys but in this case I need the science experiment (copper pipe & magnet) to be as large as the one in the video for the class room. Any ideas where I can get said sized items?


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## barnesrickw (Feb 6, 2014)

The KJ magnets mentioned above can source the magnets.  That size can really smash your hands if you weren't aware of that.  The copper might be difficult and expensive to find. 


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## mu38&Bg# (Feb 6, 2014)

I can't think of anywhere you'd buy copper pipe in those dimensions. It was probably cut from solid and 4" round copper is almost 700USD/foot. Aluminum will show the effect, but the magnet will fall about twice as fast. Copper has less resistance so it works better for this demonstration.


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## rythmnbls (Feb 6, 2014)

Online metals has the copper tubing. They sell up to 6.5" tubing with a wall thickness of 0.5", at that size it wont be cheap.

http://www.onlinemetals.com

Regards.

Steve


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## barnesrickw (Feb 6, 2014)

If you just need to float the magnet slowly down tubing from big box stores will work, I used about a three foot piece. But if you need to show the induced current that allows you to push the copper around with the magnet, you will likely need the big expensive stuff. 


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## dman (Feb 11, 2014)

http://www.amazon.com/dp/B00123YGCC/?tag=skimlinks_replacement-20

as for metal, aluminum, brass and bronze will also work well. but depending on where you live it might be hard to find a piece of hollow round stock.


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## Swifty (Feb 12, 2014)

I just want to know how they ship those big magnets, don't they stick to postal sorting gear?

Paul.


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## barnesrickw (Feb 12, 2014)

Magnets are shipped in a really big box relative to the magnet held in the middle of the box.  As strong as they are, the only have a certain range. One of my physics professors brought a large one in for the same demonstration.  Told stories of broken fingers when people have had their hand between the magnet and metal.  


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## BaronJ (Feb 12, 2014)

barnesrickw said:


> Magnets are shipped in a really big box relative to the magnet held in the middle of the box.  As strong as they are, the only have a certain range. One of my physics professors brought a large one in for the same demonstration.  Told stories of broken fingers when people have had their hand between the magnet and metal.
> 
> 
> Sent from my iPad using Model Engines



Hi Rick,
I've been bitten a couple of times by the ones salvaged from old HDD.  Particularly the big ones from the old full hight 5" SCSI drives.  They are mean suckers...


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## barnesrickw (Feb 12, 2014)

Getting them stuck on a metal surface is fun too.  If you can't slide them, you might as well just leave them there. 


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## BaronJ (Feb 13, 2014)

Hi Rick

Yes I agree !  I've used mole grips to get them unstuck.  Then you have to figure out how to get them off the mole grips.


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## MCRIPPPer (Feb 25, 2014)

i did this experiment using a magnet out of one of those "shake to charge" flashlights. the magnet is about 3/4" long, about 5/8 diameter.


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## footloose (Mar 3, 2014)

I'm new on here, so I hope you chaps won't mind me joining in with my effort at this.


[ame]http://youtu.be/6gn6ctaefPk[/ame]

I used a piece of copper that I got from a car boot sale. The magnet was from ebay.

Bert


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## BaronJ (Mar 3, 2014)

Hi Bert,
Welcome to the HMEM forums.  Nice video. 

The same trick can be done in reverse by dropping a copper coin or disc between two magnets.  In fact this is one of the ways that coin sorting is done in slot machines and other devices that take coins.


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