This little motor spins like crazy!

The left vertical nail is wrapped clockwise, and the right is counterclockwise.  When connected to DC current, this makes these two nails become electromagnets with opposite poles facing upward.  My nails are wrapped from bottom to top, then I continued back from top to bottom (do not change directions!).  Try not to let the wire overlap.  Keep the coils tight and next to each other.  (below you will read about the armature, which I also wrapped twice and never changed direction... I have seen students make working motors with only one layer of wire, so I don't know what is best here!)

The T shaped armature in the middle is what spins around.  It is wrapped entirely clockwise, with each end of the wire running down an opposite side of the piece of glass that it spins on .  Current gets to the armature by temporary connections. The wires from the two vertical nails just barely touch the wires along the glass.  When the current is on, the armature becomes an electromagnet and repels the two vertical nails....   AND IT SPINS 

This way, every half-turn, the wires switch and so do the poles of the armature.  This keeps the motor spinning.  Without these delicate connections (sometimes called BRUSHES) switching all the time, the motor would stop after just half a turn. 

the nail is filed off to a point so the armature spins easily on its own. 

maybe a metal bb in here would help, or maybe grease too?

I used a small piece of glass tubing,

but I've seen students use pen caps and other stuff

 
these contacts are temporary.  you want them to "brush" up against each other just when the armature is pointing at the two standing end nails so the current can flow through all three pieces of wire.  when this happens, the armature will repel the standing nails and off it goes!

Common mistakes and problems:

pick a side of your armature and run your wire up along the tube (the tube is what slips over the standing center nail).  Choose a direction, either CLOCKWISE OR COUNTERCLOCKWISE and wrap the wire in a nice and tight coil out to the end.

then continue back toward the middle.  Try not to let the second layer sink down into the first layer....  maybe a layer of tape over the first layer will help.  Continue all the way to the other end.  DO NOT CHANGE DIRECTIONS OF YOUR COIL!  Keep going in your original direction.

Remember, this is all one single piece of wire!  If you do run out and have to splice another piece on, then you'll need to scrape off the insulation and solder the two wires together.  After that you'll have to re-insulate that portion, maybe with electrical tape. Then continue back to the middle and come down.

Hopefully your final product will look better than my "paint" drawings!