Balancing a prop is one of the most important things when building a multicopter or a plane. In this article, I will be using a slowfly 2 blade plastic prop as an example. Please note that the method differs depending on the prop type i.e. 3 blade prop, wooden prop, etc.
It pays to have a good prop balancing tool. There are many methods to balance a prop. Provided below are some of the key steps I use to balance props and their hubs for the best possible flight and video stability.
- Make sure the prop balancing tool is on a level surface
- Place the prop in the prop balancing tool
- Centre the prop as close to a horizontal position as possible and observe which way the prop falls. This indicates there is an imbalance with the heaviest side falling lower.
- Sand the prop using a fine sandpaper on the underside.
- Repeat the above steps until the prop remains level as close to the horizontal position.
To rule out the hub being imbalanced, flip the prop 180 degrees on the prop balancing tool. If the prop falls to the opposite side, it’s most likely that the hub is not imbalanced and the prop is the only culprit that requires correction.
If the prop does the opposite in the different orientation, the hub is imbalanced and requires a correction (refer to section further below for hub balancing). Once you have balanced the hub, repeat the above steps and continue through to step 4.
Note that if the prop falls fast, there is a higher imbalance requiring more sanding. If the fall is slower, less sanding is required. It’s best to sand a little at a time to ensure you don’t remove too much material which will require the opposite side of the prop to be sanded.
Note that it’s not always possible to have a prop perfectly sitting level. In most instances, the prop will fall really slowly to one side which is observed as you continue to sand and retest the prop. As close as possible to remaining level is acceptable.
Written by Thomas