Thank you for your reply, the calculator is cool.
What I meant with my proposal is the following idea:
You draw a mecanical piece with the original dimensions (1:1). You use the dimensions and the measures represented are correct.
Now your mecanical piece is a little bit complicated an you want to show a detail or part of your drawing in another scale, let's say you copy a part, enlarge it by factor 4. So far there is still no problem.
As soon as you want to represent the mesures by dimensioning, this part all the values are wrong because they are multiplied by four, of course for the system there is no problem because it doesn't know that you only want to show a detail in another scale BUT with the original measures.
Actually I see no other solution as to manually edit all values and correct them.