ORIGINAL: DenverJayhawk
Make sure you center the washer on the prop before tightening the nut. The nut on my OS 95 has a tapered end that automatically centers the washer as you tighten the nut. If you are just using something like a spinner nut and you don't center the washer (if still using one), you can get vibrations throughout the entire model.
DJ if you have to center the washer before tightening the nut, you have the wrong washer and should replace with a factory washer. The purpose washers that come with most engines are not neccessarily related to common washers of the same size.
For example engines that use the popular 1/4/28 threaded crank use a sized washer that is not the same as a common 1/4 inch flat washer which is much to loose.
Landeck I know what you mean and its always a great feeling when you pickup some snippet along the way.
Machined spinner nuts were the domain of high performance users in controlline speed, glow powered free flight and RC pylon untill around twenty years ago when the sport flyers started demanding them.
I consider them an absolute must in the training environment as hugh time savers and safer than the common plastics. For training those plastic spinners should be discarded for the flight time stealers they are.