Do you know, że… ?
You can easily change the scales available in the drop-down list when creating a drawing. For example,. there is no scale as standard 1:2.5 or 2.5:1. But the scale is there 50:1 whether 100:1, which in many situations are not used.
Of course you can choose User-defined sheet scale and enter the expected value, for example 1:3. This scale will actually show up the next time you expand, but it will be marked Custom. Moreover, it will not be found in other documents and you cannot remove existing scales with this method.
But you can edit the file drawingscales located in the SOLIDWOKRS installation directory > only.
In the right standard, e.g. ISO you can add the appropriate scales or delete the existing ones. Remember to use an appropriate separator! 
From now on in each defined scales will be available in the drawing.
