Author Topic: is posible to re-shape a magnet? (Read 11872 times)

cicrblade · « **on:** October 26, 2009, 11:27:20 AM »

Hi,

I'm a newbie. so I'll ask a newbie question.

it is possible to re-shape a magnet??

by heat?

can I take a magnet and melt it, re-shape it, and still will work? or it will lose its properties?

tanner0441 · « **Reply #1 on:** October 26, 2009, 11:54:28 AM »

Hi

If it is a Neo magnet it is sintered and depending on the type can lose its magnetism at temperatures as low as 80C. There are companies that will make magnets to your spec but at what price??

Brian

freejuice · « **Reply #2 on:** October 26, 2009, 12:06:24 PM »

You could possibly have it cut by a machine shop with a wire EDM

freejuice · « **Reply #3 on:** October 26, 2009, 12:23:25 PM »

Have you tried a machine shop that has a wire EDM? Most wire edm's can cut about any profile you can imagine and most run submerged under water while cutting, so heat should not be a problem at all....if its only two axis you are cutting( X&Y)

they should be able to do it fairly cheaply with some quick and dirty stubby pencil and paper G&M codes.

Since the wire is brass wire or zinc coated the magnet should not affect the cutting wire at all. Just ask them to crank up the flushing parameters and it should cut right through any neo magnet out there!

All the best,

Gavin

spinningmagnets · « **Reply #4 on:** October 26, 2009, 12:33:15 PM »

Interesting question. I have heard of computer-controlled water jets cutting intricate shapes into fairly thick metal plate. The main benefit seems to be no heat warpage during the cut (as opposed to plasma-asc cutting).

It would be expensive.

Its my uderstanding (correct me if I'm wrong) that magnets are made by heating the magnet shape up above its curie point, then turning on a strong electro-magnetic field, and then cooling the subject magnets down to barely warm before they turn off the electro-magnet.

I've wondered about using a dremel and an abrasive disc to cut rectangle neo's into wedges, while applying cooling to the backside of the magnet, but I have never done that. Don't know if it would work or not.

Flux · « **Reply #5 on:** October 26, 2009, 01:54:35 PM »

What sort of magnet?

Yes Tungsten and chrome steel magnets can be forged to shape, re heat treated and magnetised.

I assume the cast magnets such as alnico can be recast and again heat treated and re magnetised. The isotropic varieties will need to be cooled in a magnetic field during casting.

None of this is within the means of ordinary people.

Sintered materials such as ferrite and the rare earths can't be treated in this way. If heated to the point where they demagnetise they need large magnetic fields to re magnetise them and with the exception of ferrite it needs capacitor discharge.

The others are discussing re shaping neo by various means, this is possible but once you destroy the protective coating you have a problem with corrosion. If you take care you may be able to protect them enough for use in dry environments ( short term at least). This is not the question you asked.

Flux

Jerry · « **Reply #6 on:** October 26, 2009, 03:41:07 PM »

If it was posable to post a picture in this responce I could show how I cut my magnets for reshaping.

Unfortunetly this new killer system were using here now won't let me do that. Besides I've deleted all 577 of my files pictures so there gone anyway.

I just used a littel cheap wet type tyle saw. You need to space the magnet above the steel saw table with somthing none magnetic so they'll slide.

A picture here would help, OH well forget that. I don't see a place here in this responce to post a picture anyway.

I sure liked the good old days.

Jerry

TomW · « **Reply #7 on:** October 26, 2009, 04:17:56 PM »

Jerry;

By deleting the files even if we get it fixed all pictures you had included previously are now gone.

Again, nothing I can do so sorry.

Tom

Jerry · « **Reply #8 on:** October 26, 2009, 07:45:45 PM »

Well thanks for trying Tom.

I'm sure it will all work out in time.

Jerry

willib · « **Reply #9 on:** October 26, 2009, 08:50:03 PM »

Jerry why on earth did you do that?

Please dont anyone else do that

I realize that you must be frustrated but that isnt the way to go about it

all your great photos in all your posts are now sadly gone.

i myself have over 900 photos in my files that are strewn through my postings and my comments , and i cannot add any more because i have hit a file limit or some such thing , if i was to delete them, no great loss , but yours were, well ,very good!

cicrblade · « **Reply #10 on:** October 27, 2009, 07:27:44 AM »

thanks all, for the comments.

my intent was to try to reuse. some magnets that i run into from old electronic devices. so my first thought was to melt the magnets and reshape them to later use.

I had read in some sites that piling up "hard drive disc" magnets together will strength their field.

in my current state I don't have any access to almost any kind of machinery. as a DIY enthusiast I have started to try to make a windmill has a protect. but before spending like 2 thousand dollar in pieces I want to construct I test project for the sake of learning.

my haul consist of

many radios speakers,TV,a microwave and a couple of hard drive.

I don't mean to be stingy. sure there are a started kit some where fairly cheap.

but I really want to try to reuse what. I have read for about 3 months and I think it is time to move to experimentation.

also I'm short on tools.since melting and reshaping is out of question.

so I ask.

cutting and piling together pieces of magnets will do it? most speakers have ring magnets. so can I cut them and pile pieces together to achieve a stronger field?

regards.

wooferhound · « **Reply #11 on:** October 27, 2009, 08:20:47 AM »

You can get magnets great for Stacking at DealExtreme

http://www.dealextreme.com/products.dx/category.1105

They are really cheap and the shipping is free

Jerry · « **Reply #12 on:** October 27, 2009, 08:40:40 PM »

willib.

I just checked some of my stories and diaries and they still have my pictures.

Could that be because they were posted befor this most recent board change?

Any way I'm happy to see they are still there. Can these picture be extracted from a story and duplicated in my files.

Thats not nessesary think thinkin HMM?

Jerry

cicrblade · « **Reply #13 on:** October 28, 2009, 07:00:18 AM »

hi there,

is there a rule, about stacking. magnets together?

I mean. if I have a 1cm x 1cm magnet with a pull force of 0.5 pounds if I stack ten of them if there a way to calculate how much the magnetic field will increase?

ghurd · « **Reply #14 on:** October 28, 2009, 07:47:55 AM »

Doing a test is good, but probably want to give the test a little bit of a chance of success.

Speaker magnets are lame. Very, very lame.

Microwave magnets are better but far from great. See windstuffnow Ed's 'alt from scratch'.

HD neos are thin, and it will take a LOT of them to do much at all.

I don't think 100 completely randomly scrounged HDs will be enough suitable neos to make 50W.

"Dastardly Dan" did a dual rotor with HD neos, but he named so many stories the same it will take some time to sort through them.

I did a small 3-ph motor conversion that took about the best magnets from 32 of the best HDs.

http://www.fieldlines.com/images/scimages/2050/3phHD.jpg

I decided it is cheaper to Buy magnets than scrounge HDs.

The money saved by using cheap magnets is not much. Small or weak magnets need more copper, and more resin, and more work, while not giving much reward at the end of the ordeal.

G-

electrondady1 · « **Reply #15 on:** October 28, 2009, 08:14:51 AM »

jerry i beleave the photos are comeing up because other people have copied your photos to their files and the program can retrieve them .

could be wrong.

electrondady1 · « **Reply #16 on:** October 28, 2009, 09:06:13 AM »

investing in a wet tile saw(even a used one)is a great move if you are interested in playing with ceramic mags.

i have cut up a lot of speaker mags.

once my friends found out i was interested, they kept dropping them off.

your hands get really dirty in the process !

you can also use them on hd mags.(a lot cleaner)

you can stack hd mags up.

unless you have a very large source of hard drives you will find it next to impossible to get matching thickness or surface area .

as a solution i measured the thickness of each mag and sorted them from thickest to thinest.

then stacked the thinnest onto the thickest and so on .

ending up with an asortment of mags that are average in thickness.

kind of time consumeing.

you can create larger magnet poles by laying out individual magnets side by side.

they don't like to stay like that and you will need to retain them while the glue sets up.

at some point you need to question what your time is worth .

that 's when it makes sense to purchase matching magnets with the dimensions and field strengh you want.

good luck!

.

ghurd · « **Reply #17 on:** October 28, 2009, 10:32:25 AM »

I'd like to take that a step farther...

When I was collecting HDs, I separated the AL, copper voice coils, SS, and platinum. It was easy at the time, so I did it.

The scrap value was astounding. I had no idea. And I got screwed on the platinum.

The magnets in a typical HD are worth about 30~40 cents average when compared to purchasing matching magnets?

The scrap HD parts were worth more than the neos.

I admit I had a disproportionately large percentage of full sized SCSI drives.

If someone would like to collect HDs to save money, probably be better off disassembling the HDs for scrap, then using the money to buy matching neos!

G-

Fieldlines.com: The Otherpower discussion board

News: