The “V” rollers were a cheap and easy design, but after using it for a while, I’ve come to the conclusion that they just aren’t up to par, especially on the X and Z axis. They need to be preloaded too much to keep the slop out of them, and with this preload, they can wear out the surface of the roller and rail.
I’ve recently upgraded the Z axis to HiWin Linear Rails, and they are great. Very smooth, and solid as a rock.
More HiWin linear rail is on the way, and I plan to replace the X axis shortly. I think the Y axis will stay using the “V” roller design for now. I’ll probably add more rollers to distribute the load, which will also add more strength. I was never really happy with the carriage design that linked the Z and X axis, but with the new linear rail, I think I’ll be set.