8 mm Rod One-Way Ratchet Clutch
A print-in-place one-way ratchet clutch: a 70 x 70 mm base plate (4x M4 clearance holes on a 57 mm square) carries a toothed housing, and a knurled Ø64 mm knob-hub rides inside it on three flexure pawls — turn it clockwise and it clicks over 21 teeth (17.1° per step), turn it back and the pawls lock against the steep flanks. The hub takes an 8 mm smooth rod (8.3 mm slip-fit bore) locked by an M3 set screw, so it works as an anti-backdrive for a hand-crank winch, gate or lift. 24 mm tall, prints as two captured pieces with 0.4–0.9 mm clearances, no supports.
mechanism ratchet one-way-clutch 8mm-rod