How to Connect a Motor to a Shaft

How to Connect a Motor to a Shaft? A Step by Step Guide in 2024

If you are a man of self-help and prefer to do all the mechanical chores by yourself, you must have the knowledge about motors and shafts. Placing the motor on its shaft is one of the first steps to setting a motor in a device. If you don’t know how to connect a motor to a shaft, it’s time to learn it.

What is a motor shaft?

What is a motor shaft

A shaft is commonly known as a component that rotates and transfers power through a machine to the whole structure from a driving device like a motor. The motor shaft is a circular cross-section and the central portion of an electric motor. If I describe it scientifically, it is the laminated part of the motor that transmits electrically created torque power through a running positive situation in the transmission.

Coupling of the motor shaft

Coupling of the motor shaft

Motors are generally connected to the shaft by various kinds of couplings. These couplings make mechanical flexibility and give tolerance for supporting shaft misalignment. Each of the couplings has a distinct torque spec. You can select them suited to your motor and shaft. They are mainly called:

  1. Fixed coupling [ open coupling, muff, and sleeve coupling, split muff or compression coupling, flange coupling etcetera]
  2. Flexible coupling [ Universal coupling, Oldham coupling bushed-pin type coupling etcetera]

You can find the nature and method of every coupling if you search them. You can choose any one of them and follow the method. When you are ready with the adapter plate of your engine, you start thinking about setting the motor to the shaft. These couplers need to get the driveshaft to be connected to the electric motor. It is part of the transmission. You also check our guide for High pressure vs high volume bike pump.

Things you need:

Motor- Take a brushless motor, with tons of torque, great precision, a balanced gob for grabbing the torque, and importantly doesn’t grow much heat while working.

Shaft- You can find shafts in many sizes and shapes. Choose yours according to your motor.

Screws, screwdriver, safety gloves, safety glasses (not mandatory).

Steps of How To Connect a Motor To A Shaft?

Steps of How To Connect a Motor To A Shaft

There are dozens of ways to connect the motor to a shaft. Some are-

  • Set screw/grub screw
  • Through taper pin
  • Interference fit
  • Split ring
  • Taper lock
  • Welded
  • Keyway and key

The keyway and key method are the most common option that people chose.

Here I’m showing the connection process of a car motor and the servo motor with the various types of shafts. First, the “Servo motor” is on the way. It will be done with the method called “set screw shaft coupling”. This servo motor has a setup on it to welcome the shaft.

Step 1

Take a little brass piece that is broached at one end. A quarter-inch diameter will on the other end be enough for the brass piece to fit on the servo. You also check our guide for How to Clean Lifters Without Removing?

Step 2

Take the servo screw and screw it down to make it permanent.

Step 3

Take a D Shaft. D shafts have a set screw that helps to fit on the flat body. It needs to be fitted because the shaft keeps spinning and biting into the motor. Slide the shaft right into the brass piece with the motor.

Step 4

Tighten the screw down and it will hold the shaft in place with the Motor.

Now if you are not comfortable with the set screws and want to re-index your project quicker after assembling the motor, you can use the “Servo Shaft”.

Step 1

Take the little servo shaft of 3/8 diameter, broached, made of aluminum.

Step 2

It is amazingly strong. Grab the tiny shaft and just fit it to the servo with one screw. Take a motor shaft coupler with the proportion of 3/8 quarter inch and set it onto the little shaft. It just fits right over.

Step 3

Now take the main round shaft because the coupler has a clamping style. Slide the shaft into the coupler.

Step 4

You will see two pinch bolts. Snug those up first, then tighten them well. The bolts will hold the shaft in place.

Now if you are connecting the motor of a car engine, the process is vast. Here we are going to use the Jaw coupling/Spider coupling and the keyway and key method.

Step 1

Take a solid two-part Spider coupler. It is a metal substance with a hole in the middle to fit the shaft and has set screws. Two parts are of two sizes for perfect matching. There is a spacer between the two parts.

Step 2

Mount the coupler into the vehicle with a bigger shaft chosen according to the size of the coupler. Make the set screws tighten down. For this kind of coupler, you need a smooth round shaft with a keyway in them.

Step 3

Bring the motor up to it. Set the motor just by sliding it on there and placing it. Bolt the motor in place so that there is no misalignment left.

Things you need to remember:

  1. For getting the highest torque with the set screws, they must be clamped down hard onto the shaft. Having a friction fit around the shaft is also a method to get high torque.
  2. If you have a DC motor, you should use the Flexible coupling/jaw coupling method. It gives torque up to 4 thousand nm and speed up to 3000-1rpm and operating temperature up to 350° C.
  3. You must use one coupling while connecting the motor because slight misalignment can happen even if the motor fixes very finely. Changes in temperature and a long period are also reasons for creating vibrations and damage. So, a shaft coupler serves significantly to reduce the damage and create smooth rotation.
  4. Use mechanical gloves to avoid any unwanted situation.

Final Words

Knowing how to connect a motor to a shaft is basic for every mechanic as well as for a general electrical craftsman. Now as you know the process, go and grab the tools and follow the process described above.