This is a very simple steady rest to support parts mounted in the 4th (rotational) axis of a CNC mill. It supports the stock while milling from the top using a down-spiral or straight flute cutter. (an up-spiral cutter would lift the stock) It is designed for T-slot tables with M6 bolts. Requires: 2x 608ZZ skateboard ball bearings 4x M8x25 or longer hex-key bolts (or hex bolts) 4x 8.xmm washers for the bearings to not be clamped 2x M8 wingnuts 2x M8 nuts Updated: Now also works on T-slot tables with 9mm slots and 72mm gaps e.g. on the YOOCNC 6040+Z.