The first thing i did, was to disassemble the entire machine to take measurements on each part and create a complete and accurate CAD model.
As i have no other milling machine, i have to build all parts for the cnc conversation on the machine itself. Therefor the accuracy of the CAD model is essential for the success of this project. I have to rely on each dimension taken in this step or i must disassemble the machine again to re-measure something.
I used Fusion 360 for CAD and i will also use it later for the CAD/CAM stuff. It's pretty amazing what great pieco of software autodesk offers with Fusion 360 - for free!
The model is public availible here: http://a360.co/2sNcVZy
Feel free to contact me if you need some specific model parts or detailed views ;-)