Power Lapping Propellers

Chris (machinist) lapping props on shaft while turning in the shop lathe.

Power lapping propellers and couplers onto shafts is a real “must” for a high performance alignment and vibration-free installation.  Our machine shop always laps props and couplers.  The propeller shaft is loaded into the lathe and the propeller is support by an overhead hoist.  A lapping compound is spread onto the shaft taper and while the shaft spins in the lathe the prop is repeatedly pressed onto the taper.  The lapping compound acts to grind the prop hub and shaft taper until there is a perfect fit between the two.

Why do this?  A perfect fit where all mating surfaces are in contact is the strongest fit.  Also, an imperfect fit might lead to a prop that is slightly cocked to one side or off-balance, creating a vibration.