Extruding a sketch the distance between two points/faces on separate components

[richard_sim]

I'm creating a cartesian X/Y gantry system parametricaly, with the dimensions of the model all stemming from a few basic dimensions of the linear rails and extrusions. I'm trying to create an extrusion for a cross-bar between two uprights (each are separate components, all with joints keeping them in place relative to the parametrically driven parts), and I want its length/extrusion distance to be the distance between the uprights. I'm not sure how to approach this however, as I don't think I can just dimension a sketch (while keeping everything up-to-date as the parameters change) like I would if this was all a single Component. There's no way I can easily calculate an expression for the distance, as it's based on the offsets and sizes of various brackets, rails, etc relative to the parameters I do specify.

[TrippyLighting]

What exactly is the question ?

[richard_sim]

Sorry that my question wasn't terribly clear - the problem is that I don't know what the solution is of course, and that's making it hard to phrase the question directly.

What I'd ideally like to be able to do is create a dimension between two locations on separate Body's (which are also in diffent Components), and then use that dimension to drive the Distance of an Extrusion (which is on a Sketch in yet another Component). I'm pretty sure that's not possible, so I'm looking for an alternate way to achieve that same effect.

[HughesTooling]

The only way you could do that at the moment would be if you used a joint between the 2 components then used the offset parameter to drive the sketch. Like this where there's a rigid joint between the 2 part with on offset of 50mm(d22)

Mark