Boolean doesn't work? I am trying to use the difference mode to make a hole.



But when I select Difference and the object it does this?



I removed all the doubles and recalculated normals on both objects but it still does this?

Blend file
It was a scale / normals problem : your objects scales were negative.

I applied rotations and scales ctrlA, then adjusted the normals (in edit mode ctrlN for both objects). 

Then your model is ready for the boolean (difference) :