Nowadays there are many indoor helicopter, those are fixed pitch and the blades are very light, however, for the collective pitch CCPM helicopters, their blades are heavy compare to the fixed pitch blade, so we need to do the blade balancing.
Why we need to do the blade balancing? If your blades are balanced, of course there are no problems, but imagine that your blades are not balanced, what will happens? the imbalance blade will cause the vibration lead to the incorrect movement of parts, so the helicopter can't keep stable.
Also as the gyro is very sensitive for the movement, the vibration may lead to the strange action of gyro, if the situation is serious, the helicopter may crush on the floor because of it.
Let's start to see how to do it: