What is Prop Adapter? Electric brushless motor has a smooth bare shaft, and you need a propeller adaptor (also known as “prop adapter”) to securely attached to the shaft, in order to mount a propeller. Nowadays many electric motors designed for multirotors come with their prop adapters, some even has integrated prop adapter. But in case you lose yours, or it’s not inclusive in the box, you might need to buy some separately.

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To learn about how to choose mini quad propellers.

Types of prop adapter

There are 3 types of prop adapters as far as I know, each with unique way of attaching to the shaft or motor bell.

Bolt-on Prop Adapter

This type of adapter will only work if your motors has bolt-on adapter mounting holes. This is the best option if your motor supports them.

Grub Screw Adapter

This propeller adapter uses grub screws to attach it to the motor shaft. They are usually used for motor shafts which have a filed area. The grub screw is tightened against the filed area, to prevent the adaptor from rotating loose on the shaft.

When using this type of adapter, it’s recommended to drop some Loctite Glue to each grub screw before fasten it.

Collet Adapter

If your motor doesn’t support bolt-on adapter, nor has a filed surface on the shaft, you can also consider using Collet prop adapters. This is probably one of the most common prop adapter you see people using. It has a collet that grabs the smooth motor shaft when propeller nut and washer is tightened down.

Which is best prop adapter

What adapter to use depends on the motor and prop you are using. I always look for bolt on prop adapter first if my motors support them. they are the better secured and tend to have less balance issue and vibration issues, maybe because the centre of mass is lower down.

For grub screws adapter, dual-screw version is better than single. If one screw comes loose, you still have the other one creating enough friction to hold it in place. They work especially well with shafts that has a flat area.

collet prop adapters in theory should work well, because it has a all round contact surface with the shaft, it should be pretty of friction to hold it tight. But I find the opposite, particularly with powerful motors and large props, they come loose quite very often even during mid flights a couple of times. You need to check it’s perfectly fastened everytime before take off.

To learn about types of propellers, check out this post.

Consideration when Buying / Using Prop Adapter

When buying adapters, you need to know:

• diameter of the electric motor shaft
• hole diameter of the propeller that you want to use
• The type of adapter you want to use (listed above)

When using prop adapters, always remember to check if they are securely fastened before take off. Loosened prop adapter not only endanger your quadcopter, it also reduces your motor efficiency as it has to spin faster to maintain desired RPM.

Last thing, most prop adapters are made of Aluminium, which is a very soft metal, you can damage the thread very easily with your pilers when fastening nuts. Just be careful.