to carve wood
彔 centers on the act of carving or engraving wood, shaping it by cutting into the surface.
彔 is thought to depict a tool for carving or engraving, possibly a knife or chisel, with the lower part representing wood shavings or the carved surface. The exact historical development is uncertain.
The top 彑 looks like a hand holding a carving tool, and the bottom ⺢ resembles wood shavings falling as the tool cuts into the wood.
For ロク, imagine carving a lock of wood: lock -> ロク, and the chisel carves the wood.