Ok - after checking out a few posts on CNCzone.com I came up with this latest idea... I found these V bearings on eBay and have been dying to try them out - they are for a "Butcher Boy" (which I really don't know what that is) and they were pretty cheap! Turns out they have a bit of play in them - and if that ends up being a problem I figure I can swap them out with more precision V Bearings if this idea holds up...

For the "track" I installed 5/16 round steel in the slot of the t-slot aluminum - in this mock up I just wire tied the ends, but if this idea works I'll probably put a few welds along the rod to hold it there permanently.

Well, for this idea the pictures really tell the story - and there's one video to see the movement...

Here's a link to the video