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Re: FABRICATING MAGNETS
From: richard hull[SMTP:rhull-at-richmond.infi-dot-net]
Sent: Tuesday, November 04, 1997 6:13 PM
To: Tesla List
Subject: Re: FABRICATING MAGNETS
At 07:56 AM 11/4/97 -0600, you wrote:
>
>From: Alan G. Pope[SMTP:agpope-at-phonetech-dot-com]
>Sent: Tuesday, November 04, 1997 10:39 AM
>To: tesla-at-pupman-dot-com
>Subject: FABRICATING MAGNETS
>
>Hello TC'ers,
>
>In connection with Tesla work I'm interested in making custom-shaped, and
>sized magnets.
>
>If it is possible, and practical within reason, I would like to buy
>rare-earth in powder form, and, in some manner, bond, mold, compress,
>shape, machine, or otherwise fabricate magnets to exact custom shapes,
>strengths, and sizes.
>
>EXACT magnet geometry is very critical for many experimental projects, and
>the cost of factory-made custom magnets can be prohibitive, especially on
>an experimental project where many sizes and shapes may have to be tried
>and rejected before finding the ones that work.
>
>I have already located some plans for building magnetizers, but would also
>appreciate more input on that, as well as how to achieve maximum
>magnetization without destroying the magnet. I believe that rare-earth
>magnets require a more powerful magnetizer than many of the less-powerful
>magnet types.
>
>I would appreciate any detailed info I can get on this, as well as parts
>and material source references.
>
>Thanks,
>
>Alan G. Pope
>
>
Alan,
Forget it. Rare earth magnets can only be impulse magnetized and that
requires capacitive discharge circuitry of a special sort. I have a friend
who actually succeed in doing it with trifilar wound 100 turn coils of 10
gauge magnet wire and dischargeing 1.2 farads at 150 volts into same and
magnetizing some rectangular Delco rare earth blanks. He did 7 magnets
before his square coil looked like a football !!!
Your real problem is the special shapes. Can't be done.... All rare earth
magnets are single piece solids magnetized through the minor axis only!
There is a physical limit in size of such magnets , also.
Rare Earth powder is available for a small fortune directly from Johnson
Mathey. They will mail you all you want provided you are a business and
have an open account.
Next, the sintering of the material will require a press capable of
multi-ton/square inch range. A good hydralic press within a furnace should
do the trick.
You would do better to make up your special magnets from existing rare earth
magnets which are dirt cheap. (hamfests).
Richard Hull, TCBOR