Hello Alan,

The safest answer to your question: Don't try it yourself, if you haven't handled them before.  This goes double if the magnets are already magnetized.

I'm guessing you have some experience because you suggested grinding & spark erosion.  Hopefully you already know that the NdFeB powder is pyrophoric and can easily combust unless kept in coolant.

There are a number of magnet fabricators out there, with the equipment & expertise for forming all sorts of shapes & sizes (check the links page).

If you absolutely, positively want to do this yourself and the magnet is not magnetized already, the safest option is wire EDM.  At least the magnet will be submerged in the dielectric fluid throughout the process.

If the magnets are already magnetized, you will get nothing but headaches if you try it yourself.

Mike

Hello Alan,
      I do quite a bit of work with neodymium magnets.  A good supplier of custom magnets is MCE (www.mceproducts.com).  They custom manufacture multiple types of rare earth magnets, if you're interested in buying new magnets.  However, neodymium might be a little expensive, depending on your budget.  I would say to go with the grinding very lightly, being careful to not let the magnet heat up or cause sparks.  I've never caught anything on fire doing this...

Keep everything wet, especially the grinding waste.
You can also slice these materials with high speed waffer saws. This stainless blades with CBN platted to the edge, high rotation speed and creap feed into the magnet.

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