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Forum Index : Windmills : cutting magnets
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| brucedownunder2 Guru  Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
I think I've visited this subject years ago ,,but here goes , anyhow. I have around 8 of these very powerful magnets ,,they are a shiny bright steel looking composition ,they seem to resist any rust over the last 10 years.. They are about the size of half a house brick -very powerful and may I add dangerous to handle ,,I use Two sets of long sleeve leather gloves and safety glasses. I would like to cut them into say matchbox or cigarette box size. Anybody out there with this sort of experience or know of a specialists factory that would do the cutting .. Do you think they may be magnetized AFTER the steel composition is machined?. and therefore, now impossible to re-machine,(cut). These are very powerful magnets ,,no way can you pull them apart,,I have to slide them away from each other with lots of care .. have thought about cutting discs, they won't look at them and the attactraction of swaft would block up the cutting disc. Thanks Bruce. Bushboy |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Hi Bruce, can you send a photo of the magnets? If they are years old, it is unlikely that they will be neodymium. If they are neo, it is unlikely that they can be cut as I believe the material is a compressed rare earth and would likely disintegrate. It sounds like they are the old AlNiCo variety and should be able to be cut and/or carefully machined. I have found though that they are still prone to chipping. Cutting might be difficult though as the grounds/swarf would cling to the magnets.??? David M. |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
OK Mobi, thanks for that .. I'll take some Photo's ,should have done that yesterday ,but while cleaning my workshop,only came across these"forgotten" magnets in piles of other junk -F&P , Seeley, re-wired stators,neo magnet rotors ,,just yesterday stuff .. but those were the "discovery" days ,lol. shiny chrome like steel finish points towards the AlNiCo type superior type magnets of the day ---.. Thanks Bruce. Bushboy |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
My concern with cutting them would be the heat generated would demagnatize the material. Neos dont recover very well once their max temp rating is exceeded and hence come with a max temp rating for the magnet On a law of average the only reason they would have a hard chrome coating would be to protect the material inside, for example Neos dont last long before starting to decay once the outer coating breaks down, and you order neos with different coatings depending on their intended use, tripple coating is about the best. So to cut a good quality magnet might stuff it up. I do recall reading about people cutting hard drive magnets with a angle grinder to score the outer surface on all sides and then snapping them, Perhaps that might work for too, and use a press to break them on the score lines, that way it would be almost a cold cut. Pete. Sometimes it just works |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
if they are alnico it's not coated. it is ground and polished from the rough casting before heat treatment. if 2 of these magnets interact fields the magnetism vanishes pretty quick but they can be re-magenetised easily. They work better with a good backing plate. need to be sure there is no beryllium-copper in a hard drive magnet before touching it with a grinder, very carcinogenic dust. I'm confused, no wait... maybe I'm not... |
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Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I have an electric tile cutter that runs water on the cutter disc that may cut with no heat build up. There is a stack of hard drive magnets just listed on fleabay. Magnets There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| electrondady1 Senior Member  Joined: 12/02/2009 Location: CanadaPosts: 208 |
a water jet would be the best method of cutting those size of mags i have purchased neo mags from a company that specializes in custom shaped magnets they use a water jet. |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
I took some Pics yesterday ,. I was thinking I could have these cut into fairly large square magnets ,,say, around 75mm square by 25mm thick -I'd get round 36 magnets .. The holes in the magnets are fairly rough sort of as if they were put in during the mould filling process,,not a smooth drilled hole that a drilling operation would achieve. The two magnetic faces are very smooth "chrome" like surfaces.. If you attach one of these surfaces to a steel surface ,you CANNOT pull them apart by hand. Bruce 
Bushboy |
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