1) acceleration (vibration) felt by the engine from the unbalanced blades of the prop = w^2 x r

Not to piss anyone off that hates math but if you look at the above equation, you will want to balance your props. When you double your RPM's (w), you quadruple the acceleration (vibration) that the unbalanced prop puts on your engine's prop shaft. When you double the size of your prop you double the acceleration that the unbalanced prop puts on the prop shaft (if you are at the same RPM's, bigger prop's are usually lower RPM's). If you triple your RPM's the acceleration goes up by 9 times. Quadruple your RPM's and the acceration goes up by 16 times. That's significant IMO.

So regardless of the prop size the formula tells you that when you increase the RPM's, the unbalanced prop wreaks havoc on the engine and airframe.

Note to scientists and mathematicians: Yes I know "w" is not really RPM's but I'm trying to keep it simple here. w is radians/second, but the concept is the same. Double your radians/second and it doubles your RPM's.

2) Use Lustercoat and spray the light tip until it balances. Add epoxy to the light side of the hub if it's off.

3) The Dubro balancer is great for big props. The magnetic one is good for small ones (Top flight?). I have and use both. I think the magnetic one is more sensitive and better for the small props (14 inches or less).