Tested a 7-pin prototype at 2 a.m., and with a 0.25 N·m thumbturn and a clutch cam the action was so buttery I relocked the lab door twice — sidebar anti-bump was flawless, operator not so much. Anyone else engineer ergonomics so good they become a security threat to the user?
I add a felt washer under the thumbturn for gentle drag; ‘too smooth’ cured?
I’d give it a tiny detent, @OP — a 1 mm ball-and-spring in the thumbturn boss riding a notched washer gives a soft ‘click’ at 0/90 without killing that ‘buttery’ feel, like a seatbelt for the thumbturn. If you want zero drilling, a thin wave spring (0.1–0.2 mm) under the escutcheon adds predictable drag. Curious whether the clutch cam is rounded or flat.