Introduction: Strong Electromagnet From an Old Transformer
The materials used are recycled from transformers and motors.
This magnet can lift over 30lbs (14kg)
Step 1: Parts & Tools
Enough magnet wire to fill the core.
Step 2: Disassemble the Core
The transformer core is made of layers of "E" shaped & "I" shaped pieces which are held together with varnish.
To separate the layers use a box knife to break apart the first layer, then beat the piece out with a hammer and screwdriver. Once it breaks free it can be pulled out with the pliers.
Once you get the first couple of layers out, put the transformer on a hard surface and hit all sides of the core with the hammer to help break the varnish loose. Then you should be able to get the rest of the pieces out with the knife easily.
Step 3: Wind the Coil
I wound this coil by hand so I didn't get any pictures in the process.
I used wire that I collected from other transformers and motors.
So I ended up twisting together about 15 strands with a drill to make about 50ft (15m) of 22awg wire.
The coil form has a divider between the coils that needs to be cut out in order to wind one big coil.
This coil has 5 layers of wire in it.
The layers must all be wound in the same direction and should be wound as neatly as possible .
This coil will run at 5 volts. For a higher voltage use more turns of a thinner wire.
When using DC to run the magnet, you can estimate the current using a wire resistance chart & ohms law.
Step 4: Put the Core Back In
For this to work as an electromagnet we will only use the "E" core pieces.
To reassemble the core, the easiest way to put it back together is to put all but a few pieces in at once. Then put the rest in on at a time, and pound them in with a hammer.
The core should stay in from friction alone, but you could use more varnish or super glue to hold them together.
Step 5: Using the Magnet
These magnets work best when a piece of metal comes in contact with all 3 parts of the core.
I find them the most useful for lifting thick, flat pieces of metal. They have very little pull with sheet metal.
The core will heat up fairly quick and should only be used for intermittent use .