Hi!
I've been CNC-ing my Sieg SX3 and recently recreated my NX CAD model into Fusion 360. Seeing as Fusion 360 has already got a pretty sizable following, and makes it really easy to share models, I figured I'd publish it:
SX3 basic - A360
It's sub-millimeter accurate with all critical dimensions rounded to the nearest tenth. All original feed screws and assosiated hardware, except for the Z nut mount and brackets, have been omitted. So has some non-critical features, like gibs and the main cavity in the base.
Hope this is helpful for some of you DIY CNC-ers. Enjoy!