half - hier
- helical screw
- helical shaper cutter
- helical spline
- helical spline broach
- helical spring
- helical surface
- helical surface error
- helical tooth
- helical tooth cutter
- helical tooth milling cutter
- helical track
- helical-gear set
- helical-gear train
- helical-gullet broach bar
- helically formed grinding wheel
- helically formed wheel
- helically profiled grinding wheel
- helically profiled wheel
- helically ribbed grinding wheel
- helically ribbed wheel
- helically-cammed
- helically-cammed surface
- helically-fluted borer
- helicoid
- helicoidal worm
- heliocentric-type reducer
- heliographic paper
- helion-neon beam
- helium laser
- helium-cadmium laser
- helium-neon laser
- helix
- helix angle
- helix cutter
- helix deviation
- helix end mill
- helix grinding
- helix lead
- helix line
- helix parameter
