Darren, the bearings you have are "self-aligning" and designed to work in pairs. If you think of the rails as the X axis, then you should have a couple of degrees of radial movement about Z, and a whole lot of radial movement about X. If you take a plate and attach both bearings on one rail to two corners of the plate, then the radial movement about Z will vanish (like in the TWN blocks) because the bearings will have "self-aligned" themselves to each other. Attach the other two bearings to the other two corners of the plate and the radial movement about X vanishes (assuming the rails are attached to something).
I hope this helps.
Steve |