Pair of Hearts Homopolar Motor

Step 9: Addendum: Some Safety Precautions

Homopolar motors are generally safe. However, there are a couple of things to remember.

1.) Neodymium is poisonous. Magnets are covered by a nickel plating that keeps the neodymium inside. Try to avoid handling chipped or worn-out plated magnets.

2.) Don't eat magnets, and keep them away from young children who might do so. It can be fatal for children to ingest 2 or more magnets because of possible pinching of the intestine.

3.) When playing with multiple neodymium magnets, always use eye protection. Two or more neos on a table will inevitably collide, and often they chip when that happens. 

4.) A point to consider is that the wire, battery and magnet can get very hot. Especially so when the Heart is not turning efficiently, or is stalled out. Be careful with your fingers until you understand about this.

5.) Don't allow the Hearts to rotate very long, as the battery will get over-heated and have a short life. If the battery feels too hot to touch, it has gone too far.

Have fun and play safe out there!

Comments

[m.hutchinson]

Neat instructable, and great warnings for kids eating magnets. One thing though, AFAIK, the neodymium nickel oxide coating not because neodymium is poisonous, but is to resist corrosion, as the neodymium is very corrosive and will "rust" away quickly.

Question - does soldering the tip of the heart together provide electrical/magnetic benefits or is it more to keep the bare wires from catching on something?

[mrfixitrick]

Thanks for the comment on neodymium. It's interesting to note that the nickel plating is poisonous also, and many people including myself are allergic to it. (It's a common allergy for mechanics).

The tip of the heart is soldered to provide a good electrical connection to the commutator/magnet, and for better looks. It doesn't seem to affect the running to have "loose legs" on the heart.