Take a close look at the bearings used to guide along the rail (U groove and V groove bearings work well for this type of linear rail mechanism). I know, you're saying that this method is used on other CNC machines. Sure, but he is positioning the bearings and using minimum hardware to serve multiple purposes. You can see that he is using the same shaft for each pair of [v groove bearings] . The back bearings (the bearings to the right) glide horizontally along the y-axis and the front bearings serve the z-axis up and down movement. This linear motion mechanis for the y and z axes is very clever. Octavio is currently trying to reduce the gantry weight. He says that the z-axis alone is 50 pounds. He has a goal of 20 pounds by changing the metal to aluminum using stamped parts.

As you can see in the images, the chain is connected to a bearing that is driven by the motor on the other side. As I have said in many parts of the website, backlash can be introduced in a machine at various parts including the lead nut, couplings, clamps/nuts at the bearings, gears, and pulley mechanisms. With the use of a chain and a sprocket, the backlash is minimized as long as there is sufficient tension. Tension is only required in a chain drive to reduce the backlash in both directions.

GT Series oil film tables are designed with general-purpose V-Groove bearings, combined with a magnesium or aluminum slip plate. Oil is supplied through portholes in the granite slab and is dispersed throughout the underside of the slip plate. The oil film provides a low friction surface, a damping medium for restraint of resonances, pitch and roll moments. Yaw restraint is provided by the V-groove guide bearings combined with the armature guidance system.

GT Series guide skf bearings are primarily designed for use with ETS Unibase shakers but are available for any existing or new shaker.

Light weight magnesium slip plate

Economical aluminium slip plate available

Self contained oil reservoir with filter

Yaw restraint provided by V-groove guide bearings combined with the armature guidance system

Less expensive technique to perform horizontal testing

I don't think the goal is to "eliminate all axial loading" I think the goal is to eliminate all slop in the axial direction without putting axial loads on parts that aren't meant to accept axial loads. I think that using a modest axial preload on the outer race of the v-groove bearings to eliminate that slop is an reasonable approach, given that V-groove bearings are ostensibly designed to bear axial loads.

The trick seems to be finding the right flanged sleeve bearings. I didn't find anything on McMaster available in the sizes we'd need for this particular job in 5-10 mins of searching. While the quasi-floating shims illustrated in the original proposal can do the job of coupling the outer races of the koyo bearings, I would prefer a more stable, less float-y solution, like the one illustrated in my quick-n-dirty illustration here.