I built a electro magnet and I did things a little different than I have seen most people do it. I would like to describe how I built it and what the thought process I had was and see if I was anywhere close to correct. so what I did was take a small iron pipe with about a one inch ID and fill it with small iron rods and wrapped that with about 100 turns of 18 gauge automotive wire. I then took a bigger pipe and wrapped it with 100 turns of wire I did this with 4 different pipes all getting progressively bigger. I then put one inside the other and wired them all up in series using one side of the inside pipe as one pole and the opposite side of the outer pipe as the other pole. I used a 525 cranking amps car battery and wired a potentiometer in circuit. my thought was that the inner magnetic field would be amplified by the one around it and the one around it would amplify the one around it and so on and so on making the magnet stronger. when I turned it on it was very powerful it drug a 8 inch pipe wrench across the table from about a foot away but I could only have it on for a short time before the wires started to melt. the magnet is about 8 inches long and has about 5 inch OD it weighs about 8 pounds. the problem is I don't know if I have wired it up correctly or if there are any other things I could to do to make it more powerful. any thought on how to make my magnet better or if my thought about building the magnet the way I did was correct any help would be appreciated thank you in advance.