Can a 3-axis CNC Machine be Converted into a 4-axis CNC Machine?

Converting a 3-axis cnc machine to 4-axis cnc machine

Custom machining has expanded beyond the streneous traditional processes. Industry 4.0 has raised the standards for many applications, and machinists must rise to the occasion. In CNC machining, the complexity and capabilities of a machine can significantly impact productivity and the range of tasks it can perform. 

One common question among CNC enthusiasts and professionals is whether a 3-axis CNC machine can be upgraded to a 4-axis CNC machine. This conversion can potentially enhance the machine’s functionality and open up new possibilities for more intricate and detailed work. In this article, we will explore the feasibility of such a conversion, including the key considerations to keep in mind during the process. Let’s get straight into it!

What Is a CNC Machine?

A CNC machine is a computer-controlled device used to manufacture parts and products. “CNC” stands for Computer Numerical Control. This machine simplifies creating or modifying parts from materials like metals, plastics, and wood. It has three main components: a drive/motion system, a commond function, and a feedback system. These machines rely on digital instructions from CAD and CAM software. CAD software designs the part, and CAM software converts this design into a G-code that the CNC machine can read. This automation often makes manufacturing faster and more accurate than manual methods.

CNC machine tools are versatile, capable of creating a wide variety of items. They generally operate in two frameworks: open-loop or closed-loop systems. In open-loop systems, the operator uses CAD software to create the numerical control instructions and generate the G-code. The computer sends these instructions to the controller and connected servo motors. These motors move cutting tools, like lathes or grinders, along at least two axes (X and Y). High-end CNC machines can operate along several additional axes for increased versatility and precision.

Closed-loop systems provide feedback to the monitor to correct inconsistencies in real time. This feedback allows the system to adjust the velocity, position, and feed rate of the tools, ensuring precise operations.

What Is CNC Machining?

Cnc machining process

CNC machining uses pre-programmed software to control factory tools and machinery. It can manage various complex machines, including lathes, mills, routers, and grinders. It completes three-dimensional cutting tasks with a single set of prompts. When activated, the system programs the desired cuts into the software, which then directs the tools and machinery to execute the tasks, similar to a robot.

In CNC programming, the code generator within the system often assumes flawless mechanisms, even though errors can occur, especially when cutting in multiple directions simultaneously. The part program is a series of inputs that outlines the tool placement in the system. CNC programming is stored in the computer’s memory and written and edited by programmers. This gives CNC systems greater computational capacity. CNC systems are also flexible, allowing new prompts to be added to existing programs through revised code.

Common CNC machining techniques include CNC milling, turning, drilling, grinding, 5 axis cnc machining, etc.

3-axis Vs 4-axis CNC Machines 

3-axis vs 4-axis cnc machines

3-axis and 4-axis CNC machines use the same basic technology but differ greatly in their capabilities. Some of these include:

  • Movement Axes: The main difference between 3-axis and 4-axis CNC machining is the movement axes. These axes determine the direction a cutting tool can move. Consequently, 4-axis CNC machining allows for more movement than 3-axis CNC machining.
  • Programming: 4-axis machines need complex programs to control the cutting tool’s movement in multiple directions. They involve many more variables. In contrast, 3-axis CNC machines use simpler programs.
  • Positioning: Higher axis machines offer more positioning options. Thus, 4-axis machines provide more positioning flexibility, while 3-axis machines are more limited.
  • Part Complexity: 4-axis CNC machines can create more complex parts because the cutting tool reaches more difficult angles.
  • Lead Time: 4-axis machines complete parts faster than 3-axis machines. This increased speed comes from multiple cutting tools working on the part simultaneously.
  • Operator Training: Operating 4-axis CNC machines requires highly trained operators due to their complex setup. In contrast, 3-axis CNC machines can be operated by individuals with lower skill levels.
  • Customization: 4-axis machines offer more customization due to the cutting tool’s greater freedom of movement, allowing parts to be modified in various ways. In contrast, 3-axis machines require repositioning the part for customizations, making them less versatile.
  • Material Compatibility: Some materials are challenging to machine, and using 3-axis machining processes can accelerate tool wear. However, 4-axis machining is more suitable for such materials because these machines can approach the workpiece in a way that reduces tool wear and simplifies the machining process.
  • Error Accumulation: 3-axis machines can only work on a single face of the workpiece, requiring multiple setups. Each setup introduces an error margin, which accumulates with additional setups. In contrast, 4-axis machines can create precision parts in a single position, eliminating error accumulation.
  • Tool Lifespan: 4-axis machines offer more options for tool position and angle, allowing the use of shorter tools. This increases accuracy and reduces tool breakage. In contrast, 3-axis CNC machining projects approach the workpiece perpendicularly, which increases the risk of tool breakage.
  • Secondary Finishing: Both 3-axis and 4-axis machining often need secondary finishing to improve the workpiece surface. However, 3-axis machined components typically require more secondary finishing and post-processing.

How to Turn a 3-axis to a 4-axis CNC Machine

Converting a 3-axis CNC machine to a 4-axis CNC machine involves adding an additional rotary axis to enhance the machine’s capabilities. The first step in this process is to choose the appropriate rotary axis for your needs. The two common options are the A-axis, which rotates around the X-axis, and the B-axis, which rotates around the Y-axis. The A-axis is typically used for tasks such as cylindrical engraving and milling, while the B-axis is useful for tilting the workpiece to achieve more complex geometries.

4-axis cnc machining process

Once you have decided on the type of rotary axis, the next step is to acquire a suitable rotary table. This table should match the specifications and capabilities of your existing CNC machine in terms of size and precision. Ensure that the rotary table you choose can be integrated into your current setup without extensive modifications.

After this, you need to integrate it mechanically with your CNC machine. Install the rotary table securely on the machine’s bed, ensuring that it is firmly attached to maintain stability during operation. You may need to drill and tap mounting holes if your machine does not have them pre-installed. Proper mechanical integration is crucial to prevent any movement or vibration that could affect machining accuracy.

The next step is the electrical integration of the rotary table. This involves connecting the rotary table’s motor to the CNC machine’s control system. Typically, this requires wiring the motor to an available axis controller on your CNC controller. If your current controller does not support an additional axis, you may need to upgrade it to one that can handle the extra complexity. 

Following the electrical integration, you must update the CNC controller to recognize and control the new rotary axis. You need to configure the controller’s software to include parameters for the new axis. Detailed instructions for adding an axis can usually be found in the controller’s manual. This will allow the controller accurately manage the movements of the new rotary axis during machining operations.

Once the controller is updated, your CAM software must be configured to include the new axis. This allows you to generate toolpaths that utilize the rotary motion of the new axis. Ensure that the post-processor in your CAM software is set up for 4-axis operations. This step ensure that the toolpaths are accurate and efficient and can take advantage of the additional axis’s capabilities.

After the software configuration, you then calibrate the new rotary axis. Calibration ensures that the rotary axis is accurately aligned with the existing axes. This process involves setting the home position and verifying the rotation angles to ensure precise movements. Perform test cuts to check for accuracy and make any necessary adjustments to achieve the desired precision.


Converting a 3-axis CNC machine to a 4-axis CNC machine is indeed possible and can bring numerous advantages to your machining capabilities. The added rotational axis allows for more complex and precise work, expanding the range of projects you can undertake. However, this upgrade requires careful planning, proper equipment, and a good understanding of both your machine and the software it uses. 

It often requires you to work with CNC machining experts to carry out the process more accurately. Moreover, outsourching your CNC machining projects to a reliable partner may be the best option for you. Weighing the benefits against the costs and complexities will help you decide if this conversion is the right step for enhancing your CNC machining operations.

Similar Posts