.001mm measures .000025 of an inch, or 25 millionths of an inch, also called a micron. .
Actually it doesn't. 0.001 mm is close to.00004".
Perhaps your problem is simply that the metric measures are simply unfamiliar?
We had a bit of that when metrication was introduced here. I was at school at the time, and so learned both systems, and so I don't have any difficulty with either of them. Metric is a great deal simpler though, especially when everything (or nearly everything) is metric and you don't have to worry about conversions any more. I can say that machinists here have no difficulty programming CNC machines in metric.
