Four stroke engines can have a nasty habit of throwing props due to pre detonation,sometimes this can be cured by increasing the mixture of the engine slightly,however some just will not hold a particular type of prop and need another locking nut in front of the standard one,there can be a problem here as with thick hubbed props there is not much room to spare threadwise,do not despair as there is a practical solution to this problem.
On the market is a product called 'Palnut' all these basically are is a metal pressing in the shape of a nut,the plus point here is that they do not have the surface area of standard nuts but will adequetly lock against a standard one,so all you need to do is find a supplier ( hardware,specialist fastener suppliers who usually give you a few as samples ).
I first discovered these in the aircraft industry where they are used a lot to fasten cowlings where space and weight is at a premium.
On the market is a product called 'Palnut' all these basically are is a metal pressing in the shape of a nut,the plus point here is that they do not have the surface area of standard nuts but will adequetly lock against a standard one,so all you need to do is find a supplier ( hardware,specialist fastener suppliers who usually give you a few as samples ).
I first discovered these in the aircraft industry where they are used a lot to fasten cowlings where space and weight is at a premium.