Hallo Michael,

that it the way jet: *.STEP to *.CATPart, *.CATPart to *.JT.
We use Programm "Process Simulate" from Siemens to simulation (Kinematics, Robotics)
MOI 3D is very helpfull for fast prototyping.

i know it is easy to JT-import. Free Tool CAD Assistant can convert JT to STEP, IGES, BREP, STL, PLY and OBJ.
But JT-Export is not possible.