Some of this is standard information, but some of it might help us all achieve better efficency with our home built alternators. Read on and read all.
Making Magnets work harder
Magnets do their best work when focused. The natural field of a magnet is a polar radiating loops. Disc magnets have equal fields. The trick with disk magnets if getting both fields working for you.
A ferromagnetic backing plate placed against one side of the magnet creates a more efficeint path for the flux lines to follow. I also creates a radiating pattern favoring one pole, which effectively points the majority of the manetic energy in one direction.
When a magnet is placed in a ferromagnetic cup, the cup further magnifies the effect by eliminating the air gap (air is a poor conductor of magnetic fields) and brings both poles of the magnet to grip on the same surface. this is similar in principle to a horseshoe magnet. A rare earth magnet in a steel cup provides four times the strength of a bare magnet. A cup provides a disc magnet the optimal magnetic flux focus into the smallest gap area.
Maximum Attraction
To increase the attractive power of a magnet, put a piece of iron or steel behind it. Any piece of steel the same size or larger than the magnet will do. For maximum effectiveness. be sure the steel is at least as thick as the magnet. Several layers may be used if necessary.
Magnets can be glued in place with most any glue although epoxy is the most secure. For mechanical mounting, try magnetic cups which are often sold with rare earth magnets up to one inch in diameter.
With thanks and Credit to Lee Valley Tools
