Here is a picture tutorial on how to proper balancing your motors.
Yes, They are as important to balance, as the propellers, whan you want to mount them on a Multirotor, or anything else hvere there are some stabilizer electronic on. All those sort of gyros and sensors are not keen on vibrations, at all.
What you need.
A small piece of hobby plywood. (Not Balsa... It will crack and break.)
A sort of mirror or shiny object. (I use a piese of carbon plate.)
A Motor mount.
A Lipo battery pack.
A solid clamp.
A bright lazer pointer.
Tape to use as the balance medium.
I recomend balancing the motor complete with prop mount. But without props. They are changeable, and balance seperately.
Here are some photos of the setup.
The setup ready to rock N roll.
The "Mirror" I used a carbon plate, the lazer i use, is bright enough for this.
Here you clearly sees the reflection from the lazer on the wall.
Here you see the tape mountet to balance the motor Spinner combo.
The test rig.
Seen from the bottom
Seen from the top.
You spin the motor up at different speeds, and see if there is some fuzzyness to the lazer dot or line.
If that's the case, try adding a small piese of tape an the side of the motor. Then you find the "Sweet Spot" where the un-balanced point is, by trial and error - moving the piese of tape arround until the vibrations get smaller. You can get really good results by this.
To seal it in, i wrap a pies of tape the entire circle of the motor, to make sure the smaller pieses stay where i intended them to. :-)
The laser is just positioned away from the thin vibrating surface (The plywood.) where you mount the motor. I mounted it on the shelf, laying loose pointing onto the "Mirror" so i can see the green (or red if you use a red laser.) dot or line on the wall.
Here the Laser beam has been visualized by the red line. For illustration only. ;-)
See the episode og Flitetest's "Laser Balancing Props" too, it's the same basics. Link below.
I have some unbeliveble well balanced FPV and Multi Rotors that almost don't require any form for camera/vibration dampening mount to get jello' free movies and images.
Hope you enjoyed this.