[AT] Metric System

[Dennis Johnson]

The dimension converison is not the significant thing in conversion between the systems. The more significant thing is material availability. In the US, you can get 1/4" plate as a material. Most other places you get 6 mm plate. These may be close, but they are NOT the same. Similar issues with formed shapes like angle, channel, beams, tubes, round rods, pipe or tube, etc.
The most important thing is that service items interchange. This sometines can be done if there is enough thought put into the initial design.
I build equipment worldwide, sometime trying to build the same item in various countries. End result is that you really need 2 different drawings to address the available material. If you have huge numbers of the same thing, you can get whatever material you want anywhere in the world.