I got a pack of the cheaper tee nuts and I noticed a lot of play in the connections. Are there tee nuts for aluminum extrusions that don't need careful alignment? How about the drop in tee nuts or the spring loaded ones? Is this a limitation for tee nuts in general? If so I'm going to have to change my plans and use plates, if those nut blocks are ever in stock again. I'm working on something like this http://www.openbuilds.com/builds/x-y-stage-hidden-acme-rod-example.66/ but I quickly realized there is no way I'm going to get those two extrusions to be parallel when I tighten everything down.