I might be wrong now, but last time I used Blender it didn't have too much in terms of CAD capability. Sure, it can 3D model but it's UI isn't built for designing. Anyhow, the big problem you'll probably run into is that I'm pretty sure it has no support for STP or IGES. I'm not even sure it supports 2D drawings, although that might just be me talking out of school. Either way, that would present a problem for you to take models into CAM.
For the best in precision pneumatics - Castor Engineering Inc.
www.castorengineering.com