Proper orientation of drawer slides?

[mikefulb]

I have been reading these forums of a couple of weeks and felt insprired to build a simple rig. I found some nice drawer slides at a local woodworking store and wanted some feedback as to if I was using the correctly? I read several sites that used drawer slides but never could tell from the photos exactly how they were used.

I have two slides facing each other so that as one extends the other is retracting. My understanding is that this will help rigidity.

At the moment my goal is a pen plotter so I'm not too concerned about weight - just trying to figure out the mechanical aspect of these machines.

Thanks
Michael