[WilliamD]

I know that flex in the shaft is a problem with these over long distances. But what if you were to cut a slot in the side, wide enough to let a support through. Then you would have the ball bushing, with the supported rod. I'm going to order one and try it. It seems like you can simply cut out on of the 6 ballbearing slides, without affecting the others. Maybe I'm way off base. The gantry would keep them fixed in an upright position, so you wouldn't have to worry about it sliding out of position and hitting the supports. What do you guys think?

[furry]

When I couldn't find a local source of inexpensive 20mm open linear bearings, I purchase 4 closed ones off VXB and opened them up by removing one circuit.

Was a big job, but they worked perfectly.

The only caveat being, the bearing housing must be rigid enough to keep the open bearing in shape and not allow it to open up any further.

With VXB now selling open bearings at quite reasonabe prices, it would be hardly worth doing now