Good morning fellow-solidworkers,

I'm having some difficulty trying to figure out how to get two parts mated together in an assembly.  For the tabletop, I have the origin set at the underside at dead center.  I wanna get this thing mated to the steel base at the center.  I drew a 3d construction line at the center of frame on top surface where glasstop will set and then inserted a point at the midpoint.  I was thinking I could just pick that midpoint as well as the origin on the top and make them coincident but the I cannot seem to pick the midpoint of the 3d sketch line in the mate dialog box (can only pick the line which won't work).  Any advice on the simplest way for a mate here?  I must be overlooking something very simple.  I won't attach the sldasm file unless needed since I have alot of parts attached to it.  Maybe from the attached screenshots, there is a simple solution that can be seen.  Thanks in advance!

Dave

ps I should have mentioned that I know how to get the top surface of frame and bottom surface of top mated using coincident but not sure how to get centered laterally without having to fiddle with dimensions to work backward with the distance mate.