However the way the question was worded I can't help but feel that perhaps the real question should have been:
Why is my part defaulting to mm's when I was expecting it to be inches?
Well if you haven't noticed, when you create a new part file you have to decide whether you are going to enter the parameters of your model in inches or millimeters. This will be an option when you using the File -> New... command. Note that you can use Customer Default to set what the default is, but even then it can be changed just before you create a new part file.
Therefore, under normal conditions, if your intentions are that you will making an drawing using Imperial Units (inches) versus Metric (mm's) while it is possible to create a drawing using units other than the default (you can even create dual-unit dimensions show a combination of any two units in the same dimension), generally speaking most organizations work in only one base set of units, period.
So make sure that you're actually working in the both the units you need to, but also the ones that you had expected, because if you mess this up, it's not pretty when you have to go back and clean it up if it turns out that the models were created in the wrong units. Drawings can be fixed very easily, models take a bit more work and the results are not always that satisfying, particularly since the introduction of dimensionality into the Expression system.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Cypress, CA
To an Engineer, the glass is twice as big as it needs to be.
