Cutting ALNICO Magnets

[Beef Coon]

I'm making some one-off Firebird pickups so trimming some magnets and cutting some steel plates.

For the ALNICO I used a Dremel with a reinforced cutoff wheel. Below are a couple cell phone pics.

I made a little wooden "cradle" to hold the Dremel on its side and clamped to my bandsaw. Made a cradle since the Dremel is more or less round and easiest way to get a nice firm clamp.
I did it this way as it seemed it would be easier to control the work piece rather than the tool. YMMV. Haven't seen a ton of info or pics of how others do this so figured I'd share.

Cutting was on the slower side as expected - great for prototyping ands one-offs though.



Reasonably straight cut, will use disk sander to tidy-up.

[jack briggs]

hope you kept it flooded with cutting fluid or water?
BTW - I've cut AlNiCo bar mags by just scoring with the Dremel and cutoff wheel, then breaking with pliers. the end can be cleaned up on a bench grinder with water quenching.

cheers,

[Beef Coon]

hope you kept it flooded with cutting fluid or water?
BTW - I've cut AlNiCo bar mags by just scoring with the Dremel and cutoff wheel, then breaking with pliers. the end can be cleaned up on a bench grinder with water quenching.

cheers,

I was going to score and break w/ pliers, but it was cutting so well, I just continued cutting. I cut the short length with a wet tile saw.

Are you saying the physical properties of the magnet will change from the heat?

Txs.

[David King]

You'd have to get the AlNiCo really hot to permanently affect it's magnetic capacity. Alnico are the most heat resistant magnets known to man.

[jack briggs]

You'd have to get the AlNiCo really hot to permanently affect it's magnetic capacity. Alnico are the most heat resistant magnets known to man.

true, you may not reach the Curie temp with a Dremel, but any grinding operation should be done with coolant.

[Joe Gwinn]

Don't try to cut alnico at high speed using diamond tooling - the diamond (which is carbon) will dissolve into the alnico, which is largely iron. If you see sparks, it's too fast.

If you make the magnetic path too short, the magnitization will prove unstable, and the reduced magnet will lose its charge over time.

[Beef Coon]

Lots of good info being shared, lots about good general practices for cutting metal.

I'll just reiterate that the method used in my original post worked very well for trimming down a couple full size ALNICO bar magnets - with no ill effect on the magnets, and no ill effects on the tool.
One reinforced cutting wheel lasted long enough to cut down two magnets. Forgot to mention that this was done outside, as the dust is nasty & these magnets were not magnetized to keep debris out of the cutting path.