Good advice! You do have to be careful how many rubber washers are used, not to mention avoiding peach pits. My first try had about ten total washers made from an inner tube. It wobbled badly at low RPMs. Inner tube rubber is not well dampened. Two to four total washers works OK at most power levels. Of course, the nut can be tightened or loosened to adjust the compliance, changing the resonance frequency. I've been thinking about how to add a damping mechanism.
regards, Carl