|Prop adapters are required to mount a propeller either on an electric motor or gearbox shaft. The shafts are usually smooth, and there are two types of adpater: those attached with a grub screw, and those that use a collet type action to grab tightly onto the smooth shaft.
When using the grub screw variety shown above on the left, it is recommended that you grind two flats on the shaft of your motor or gearbox on which the grub screws can purchase. It is also recommended that you add a drop of Loctite to each grub screw as you secure it. I have found these to be very successful if you take these precautions.
The collet type are shown above on the right - both the standard short type, and the new long versions - see new, big adapters in the left hand size bar and at the bottom of the collet type list.
Following are the sizes and prices of the grub screw type first, and then the collet type - the motor shaft size is specified, and the outside diameter of the prop adapter is as well.