- Joined
- Mar 3, 2017
- Messages
- 796
One of my mag bases was much weaker than the others, and presumably needed remagnetizing. After
stumbling over it yet again, it occurred to me that (1) it's probably an alnico magnet that
is flipped by the paddle, and (2) those alnico magnets are generally assembled with their
base block before final magnetization (but an initial polarization also happens, while it's still
hot).
The base only contacts the surface below on about 1 square inch of 'feet' so it
seems likely that a big permanent magnet, and some pole pieces (blocks of mild steel)
can put the right field into it, at high intensity. I've got some circa 200g rare earth magnets,
50x50x6mm, with the poles on the 50x50 faces, which are perfect for this.
It takes some doing to get the pieces together; the magnet first,then the large pole piece (it will take a bit of deadblow
hammer encouragement to get it adjusted), then, carefully, the smaller pole piece (more hammer work).
Then it was time for a break; you want the ON position of the lever, and the 'easy' way around for the N and S
poles of the magnet (that's the yellow-jacketed item). Fifteen minutes later I was ready to try to pull the bits apart.
The vise can hold one pole piece, then you can wrench the smaller one off... and with some
effort, the magnet lets the mag base loose.
It worked great; that base is as sticky as new, now.
As one would expect, some precautions are wise: leave wallets and magstripe cards and precision magnetizables and
electronics away from the work area before taking the magnet from its metal can safe... and watch for eager stray bits
of metal that might smack the knuckles or blemish the dermis.
There's some magnets available, about this size, on eBay, but it matters where the poles are (a refrigerator magnet
can have N and S poles on the SAME surface, you want 'em on opposite faces).
stumbling over it yet again, it occurred to me that (1) it's probably an alnico magnet that
is flipped by the paddle, and (2) those alnico magnets are generally assembled with their
base block before final magnetization (but an initial polarization also happens, while it's still
hot).
The base only contacts the surface below on about 1 square inch of 'feet' so it
seems likely that a big permanent magnet, and some pole pieces (blocks of mild steel)
can put the right field into it, at high intensity. I've got some circa 200g rare earth magnets,
50x50x6mm, with the poles on the 50x50 faces, which are perfect for this.
It takes some doing to get the pieces together; the magnet first,then the large pole piece (it will take a bit of deadblow
hammer encouragement to get it adjusted), then, carefully, the smaller pole piece (more hammer work).
Then it was time for a break; you want the ON position of the lever, and the 'easy' way around for the N and S
poles of the magnet (that's the yellow-jacketed item). Fifteen minutes later I was ready to try to pull the bits apart.
The vise can hold one pole piece, then you can wrench the smaller one off... and with some
effort, the magnet lets the mag base loose.
It worked great; that base is as sticky as new, now.
As one would expect, some precautions are wise: leave wallets and magstripe cards and precision magnetizables and
electronics away from the work area before taking the magnet from its metal can safe... and watch for eager stray bits
of metal that might smack the knuckles or blemish the dermis.
There's some magnets available, about this size, on eBay, but it matters where the poles are (a refrigerator magnet
can have N and S poles on the SAME surface, you want 'em on opposite faces).
