Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

How can I go about magnetizing something? Specifically, a whole bunch of BB's. I want to try this so that I could make a cheaper version of the Bucky Balls product. Even if I can't replicate Bucky Balls, it'll still be an interesting project.

share|improve this question
    
The price is actually pretty good. Compare with a magnet supplier I've used in the past, K&J magnetics, kjmagnetics.com/products.asp?cat=12, where 250 grade N42 3/16" spheres cost $137.50. Just steel balls, which are very cheap, will not magnetize anything like as well as rare earth balls. It's the material you're paying for, not the magnetization. –  Peter Morgan Jun 15 '11 at 16:52
    
@Peter Morgan, i figured what i end up making probably wont' be nearly as strong, but it's jsut somethign i want to play with. –  DForck42 Jun 15 '11 at 17:00
1  
I asked K&J about this, and they replied, in part, that "The price of raw neodymium has been rising very quickly in the past few months. If you want some of those, you might want to get them at that price while you can!" They have a video of magnetizing a screwdriver at kjmagnetics.com/blog.asp?p=magnet-basics, but I couldn't get a small steel ball bearing to magnetize by this kind of approach because of the awkward geometry. Doing 216 this way would be time consuming. –  Peter Morgan Jun 16 '11 at 14:11
    
Update: supermagnete.de/eng/faq/price The price of neodymium changes with time so be sure to check recent prices instead of using information from this old posts/comments. (The link shows the price fluctuation of neodymium during 2011, when this question was active)) –  raindrop Feb 24 '13 at 14:47

2 Answers 2

up vote 4 down vote accepted

To permanently magnetize them, you need to start with bb's that are made of a ferromagnetic material, e.g., iron (or some kinds of steel), nickel or cobalt. This is the challenging part. When I was a kid they made bb's out of copper. Nowadays they probably make them out of some other less expensive but equally non-ferromagnetic material.

Assuming you can find a ferromagnetic bb, the next step is to subject it to a very strong magnetic field, which you could do with a homemade electromagnet.

You can slightly magnetize the right object simply by subjecting it to high shock, for example, by striking it with a hammer; but a blow strong enough to be of magnetic benefit might squash your bb.

EDIT: Was doing a little research to answer a comment, and discovered that those "copper" BBs I shot as a kid were actually copper-coated steel BBs. So, your magnetic BBs may be much easier to come by than I thought.

share|improve this answer
    
how would i make a strong homeade electromagnet (know how to make the small ones)? Also, how long would i have to expose them to the magnetic field for them to become magnetized? –  DForck42 Jun 15 '11 at 16:56
    
The link in Fortunato's post gives a much more complete and detailed treatise on the subject than you could get from me. My method would involve cannibalizing and taking a hacksaw to power supply transformers, which some might find ... shocking. –  Vintage Jun 15 '11 at 20:58
    
""When I was a kid they made bb's out of copper. Nowadays they probably make them out of some other less expensive but equally non-ferromagnetic material. "" Please, what do You mean with "bb"? –  Georg Jun 16 '11 at 9:19
    
"bb" often refers to a small gun powered by air pressure; bullets for these guns are small spheres. They're usually not subject to the same regulations as firearms, as they're far less lethal. –  MSalters Jun 16 '11 at 10:48
    
@ Georg --> "bb guns" are an American tradition for kids in rural areas. They are CO2 or air-powered, and "fire" a 4.4mm metal ball, typically between 150 ft/s and 450 ft/s. Most of the more popular guns are spring-air riles, which are of the lower muzzle velocities. For these, maximum range is about 150 m; and maximum accurate range is about 30 m. They can take an eye out, or make your buns sting (don't ask how I know), but are otherwise benign enough to not require permits in almost all areas. –  Vintage Jun 20 '11 at 19:29

Here is a great paper on how to magnetize. http://www.oersted.com/magnetizing.PDF

Yes you are correct it is a hard paper to “weed threw” but all the necessary information is there. If you go down to the explanation on the apparatus for magnetizing you can essentially deduce that. 1) You need impact the material being magnetized. 2) You need to put the material in a strong magnetic field
3) So the magnetic field and the material must be aligned just right “A ferromagnet, like a paramagnetic substance, has unpaired electrons. However, in addition to the electrons' intrinsic magnetic moment's tendency to be parallel to an applied field, there is also in these materials a tendency for these magnetic moments to orient parallel to each other to maintain a lowered energy state. Thus, even when the applied field is removed, the electrons in the material maintain a parallel orientation. Every ferromagnetic substance has its own individual temperature, called the Curie temperature, above which it loses its ferromagnetic properties. This is because the thermal tendency to disorder overwhelms the energy-lowering due to ferromagnetic order. Some well-known ferromagnetic materials that exhibit easily detectable magnetic properties (to form magnets) are nickel, iron, cobalt, gadolinium and their alloys.”

share|improve this answer
    
Interesting, but not, I think, a guide for the home experimenter. –  Peter Morgan Jun 15 '11 at 20:54
    
@Peter Morgan, yeah, i breeed through some of it and got completely lost –  DForck42 Jun 15 '11 at 21:06

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.