English Inches to Metric Scale
1. Start with the setup file for your machine by going File....Open Setup.....
2. Go to Setup....System Options and fill in the Display Units as Metric.
3. Go to Setup..... Feedrate/Ramping and multiply every thing that is feedrate units (mm/min) by 25.4. Do not change the ramping rate.
4. Go to Setup.... Machine tool and Divide your Screw Thread for Each Axis by 25.4. Multiply everything else on the screen that is in length (mm) units by 25.4 (i.e. axis length, home offset, backlash, tool change position).
5. Go to Setup....Tooling and multiply any tool length offsets that you might have defined by 25.4.
6. Go to File...Save Setup As.... and give it a memorable setup name for metric such as MyMetric.stp
7. You can now easily switch from inch to mm by opening the original setup file for inch and the new setup file for mm.