Is there any other way without array modifier? I am looking for a way to model circular objects without array modifier. Something like this for example: 



Edit: as you can see the dimensions tab has numbers. I think that is what's messing the mesh around. Have I modelled my basic part incorrectly ? Is there a way to reset the dimensions of an object?
Maybe you can use both X and Y symmetry in the mirror modifier.

Like so..




It does depend on the complexity of your subject. In many cases Array will give you more control than the mirror modifier but for less complex objects this may be helpful.