[JesseK]

80/20 (and maybe Bosch too) sliders really start to bind on multi-stage compound elevators. You also have to keep the 80/20 perfectly square to minimize binding, and at height there's a higher tendency for torsion. We scrapped 80/20 in favor of powder coating + teflon for slide friction that was close to what a bearing slide would have; the box aluminum also resisted torsion alot better.