In my design that I'm still working on, I'm thinking of mounting supported linear rails. But, and here comes the question.
If I mount them on the side, so the Pillowblocks is mounted sideways instead of upright, would they have any problem of working in this way without making any slack over time? The reason is, that this kind of linear rail is somewhat cheaper than THK linear guides are.

But if anyone knows if supported linear rails can be mounted on the side instead of the top, please let me know.