How To Install A Woodruff Key On A Crankshaft

Have you ever seen a woodruff key? It looks just identical to a half-moon. These semi-secular keys are mostly used to use on machines, tools, and automobile crankshafts to prevent gear, hubs, snow blowers, marine propellers, or other components from moving independently of a rotation crankshaft. The woodruff key fits into a circular recess in the crankshafts and is generally used for maintaining board components on the end for transferring the torque load from a shaft to the working gear.

Sometimes the woodruff key will break. This broken key may damage the gear, hubs, and snowblowers of the car.  Therefore, you need to install or replace a new woodruff key. 

Don’t know how to install or replace a woodruff key? Not to be worried, here is the solution. 

Installing A Woodruff Key On A Crankshaft-4 Easy Steps

You can easily install a woodruff key on a crankshaft. But if it is your first time, you may face trouble. Follow the instructions step by step, you may do this without difficulty.

  • First step: Take a woodruff cutter and with the help of this tool, press the woodruff key into the semi-circular groove that is crushed into the shaft.
  • Second step: When the half-moon shape key is fitted into the shaft,                                         Then you need to parallel the woodruff with the host shaft. For this, you need to align the top, flat portion of the woodruff key.
  • Third step: Thirdly the shaft is starting to move together for assembly.
  • Fourth step: In the final stage, you need to tap lightly with the hammer for shift assembly and coupling.

Selecting The Right Woodruff Key-Different Types Of Woodruff Key

When you decide to install a woodruff key on the crankshaft, you need to know about the different characteristics of woodruff keys. Because each key is appropriate for their prospective application. Several considerations including key, key finish, and key material are important when choosing the perfect type.

All the woodruff keys are not the same. There are different types of keys. Among them, full radius and flat bottom are the most common. The works of these two keys are almost the same but appropriate in a specific application. Here we are introducing three types of woodruff keys to facilitate your search for the right one.

  1. Flat bottom key: Flat bottom key is like a standard key. The bottom of the key has been cut flat. This flat bottom key reduces the chance of interference with the bottom of the seat, allowing the woodruff key to seat fully in the groove.
  1. Full radius key: The full radius key is similar to a half-circular. It ensures full contact with the groove seat.
  1. High pro key: This key is full half circular-shaped like a full radius but slightly different at the top. It provides help during assembly.

What Are The Materials Of  Woodruff Keys?

Woodruff keys are made of carbon steel, alloy steel, and stainless steel. Both carbon steel and alloy steel are long-lasting but need to be coated to prevent corrosion. Stainless steel has the power to resist corrosion but is not durable as compared to carbon steel and stainless steel.  

What Can I do To Keep A Woodruff Key In Place?

If you want to keep a woodruff key in place while installing a mating component, ensure that the key is situated tightly in the key seat. If the key slips out during component installation, the key seems too small for the keyway.

How Do You Measure Woodruff Key Size?

You can measure the size of woodruff keys identifiable by their half-moon shape. The measurement process depends on whether it is an imperial or a metric key. If it is an imperial key, you can measure it by its width and diameter. And if it is a metric key, you can measure it by its width and height.

Bonus Tip- Things You Must be Aware Of While Installing Woodruff Key

When you will be installing a woodruff key, you may face some difficulties. Firstly, this key is difficult to install if you have not done it before. Secondly, it can not carry a high load, so you are not able to use this as a feather. Thirdly the crankshaft weakens with the depth of the keyway. And finally, you can not use this for the transmission of heavy torque.

Frequently Asked Questions (FAQs)

How Tight Should A Woodruff Key Be?

Woodruff keys are used to tight tolerance and need a press fit into their seat. So, to attain its purpose, the woodruff key needs to be tight according to the manufacturing level of tolerance for both the key and groove. The key must be fitted appropriately. If the key is too tight, file key thickness down to allow fit.

Are Woodruff Keys Hardened?

Woodruff keys are easy to machine and not hardened. A standard woodruff key is made out of plan 1035 carbon steel. These keys are used for the general purpose of applications. Woodruff keys move deep into the keyway crankshaft.

Can You Use A Woodruff Key As A Feather?

A woodruff key can be used as a feather key because it is difficult and very little to install. It is expensive and creates an installation problem to install more than one key to lift the bulk of the load. It helps to turn itself in its circular recess to make up any taper in the mating hub on assembly.


Installing a woodruff key can come with lot of complexities. But not any more. In the above discussion on installing woodruff key on a crankshaft, we tried to include all the topics that will come to your mind about woodruff keys. Installation of  woodruff key improve the concentricity of the shaft in high speed operation.

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