Dear everyone,

I have an assembly (pressure vessel) with some subassemblies (flange) in it. The assembly is a tube like geometry and I would like to mate all the subassemblies with equations. To fully define a subassembly it is needed to give 4 dimensions, these are:
- the distance from the zero point, along the axis z;

- the distance from the surface of the tube along a plane;

- the rotation degree around the centerline of the tube;

- the offset of the flange from the centerline of the tube.

I can solve all the mates except the last one since it is not possible to use negative values in equations to reverse offset direction. 

Can you advise me any solution? 

Thank you very much.

Cheers,

Lajos