# Screw: convert handle rotation into axial travel
# Scope: Ideal frictionless screw; lead is axial advance per full revolution. Shaft and handle are schematic, without thread geometry or self-locking behavior.
load = 500 N
lead = 5 mm in 2..12
handleRadius = 100 mm in 50..200
torque := load * lead / (2*pi) [N*m]
effort := torque / handleRadius [N]
mechanicalAdvantage := 2*pi*handleRadius / lead
handleLength := 2*handleRadius [mm]
part shaft "Screw shaft": cylinder 8 mm, 100 mm
part handle "Handle": box handleLength, 10 mm, 10 mm at 0 mm, 0 mm, 60 mm
check hand force: effort <= 5 N
scenario coarser lead: lead = 10 mm