In my research (lurking) I've seen at least 3 different SIMPLE arrangements using skate bearings and gas pipe. There are surely more. Please add to this list.

Thanks,

Dave

Hi

This is a variant on one of your thumbnails where two angle irons have been placed next to each other with skate bearings between (and unseen on this picture but definitely there). The assembly pictured therefore has a total of 6 skate bearings. When rotated on the pipe by 45 degrees from the horizontal, they provide support and locking control both up, down and sideays lateral.

Very cheap to make and they slide beautifully.

Andy

My design supports the pipe. The pipe is attached to the table (and gantry) and the bearings are held tight to the pipe by sing threaded rod to keep everything tight, in compression. It's not finished yet, but I've had the gantry assembled and it seems to work very well.
http://www.cnczone.com/forums/showthread.php?t=1356