DC Electric Motor Troubles

[Shnoz (Sophie)]

I have a physics assignment (due tomorrow!) where I need to construct a DC motor that has to run for at least 20 seconds. I'm almost finished, but I've hit a roadblock. The coil won't magnetise and form an electromagnet and I'm stumped as to why. There is a current running through the coil, the commutator sparks when I connect the power, but it doesn't magnetise properly. Both a north and south pole attract each ends. Any answers?

[bojan]

Could you be more specific?
Image of how the connections are done would be helpful.
However, most likely the position of brushes in relation to stator poles are not correct. There should be ~90° phase difference... meaning, when the coil is activated, the rotor should be between the stator poles. When the rotor is positioned against the poles of the stator, the brushes should be disconnected.. little later they should energise the rotor such that there is repelling.. and so on.

If you have stator coils (not permanent magnet), then perhaps one of them is reversed in relation to the other...

[wasyoungonce (Brendan)]

Did you use enamelled wire for the coil?

Aka...this is insulated wire...so the current has to flow thru the coil...not from one winding to another.