An Overview of Technical Drawings for CNC Machining

To produce precise products, technical drawings for CNC machining are crucial. Without technical drawings, producing the high-quality components required for CNC machining operations would be impossible. In this article, I will provide an overview of technical drawings for CNC machining and examine their importance in the manufacturing process. I will also explain what is technical drawing, why you need it, and how to create this correctly. So. let’s dive in!

What Is a Technical CNC Drawing?

Technical drawings for CNC machining are an essential element in the field of manufacturing. CNC machines rely on these technical drawings to produce highly accurate and precise parts. A technical drawing is a detailed illustration that shows every aspect of the part, including its size, shape, and dimensions.

The technical drawings for CNC machining are often created using Computer Aided Design (CAD) software or by hand with drafting tools. The accuracy of these drawings is critical as they serve as a blueprint for the CNC machine to follow when producing the part. A slight error in measurement or dimension can result in faulty parts that cannot be used.

What Are The Components of Technical Drawing?

Components of Technical Drawings

Technical drawings are essential for both CNC machining and Rapid Prototyping, as they serve as blueprints for the machines to follow. These drawings give a precise representation of the object that needs to be produced and guide the machine in creating the final product. Technical drawings for CNC machining consist of several components that are critical in ensuring accuracy and precision.


One critical aspect of technical drawing is understanding coordinates. In technical drawing for CNC machining, a coordinate system is used to determine where each cut should be made in relation to the part being machined. This system consists of three axes – X, Y, and Z – which are perpendicular to each other. Each axis represents a different direction within 3D space: X corresponds with left-to-right movement. Y corresponds with forward-and-backward movement and Z corresponds with up-and-down movement.

Title Block

Title blocks are typically located in the lower right-hand corner of a technical drawing sheet. They can vary in size depending on the type of drawing is used and its purpose. Suppose, smaller title blocks may be used for simple parts, while larger ones may be required for more complex assemblies. On top of providing valuable information about the drawing itself, title blocks also help with organization and record-keeping.

Isometric View

The isometric view provides a three-dimensional perspective of an object that allows manufacturers to see every angle and detail of the product.  When it comes to CNC machining, accuracy is vital. The use of isometric views in technical drawings enables engineers to create precise designs that perfectly match their specifications. This helps manufacturers produce high-quality products with exact specifications that meet their clients’ needs. It also reduces errors during production which saves your time and money as well.

Orthographic Views

Technical drawings for CNC machining typically include multiple orthographic views, including front, top, and side views. Providing accurate representations of the object or part, orthographic views also help to ensure that the design can be manufactured as intended. Including all necessary details in the technical drawings, such as dimensions and tolerances, there is less room for error during production. This not only saves time but also reduces material waste and cost.

Section Views

Section views are created by slicing through a component at a specific point and showing what lies inside. These views can help identify any potential issues with tolerances or clearance between different parts, allowing adjustments to be made before production begins. They can also highlight any areas that may require additional finishing processes such as drilling or milling.

Detail Views

Detail views focus on specific aspects of a component that require additional attention or precision, such as holes, threads, or intricate shapes. They are created using specialized software that provides an enhanced view of these features from different angles and perspectives. You can identify potential issues early in the production process and make adjustments accordingly through this view.

Pertinent Notes

Pertinent notes refer to additional information added to a technical drawing, such as material specifications, surface finishes, specify tolerances, and other relevant details. These notes provide valuable information for machinists that they may not find in the main view of the drawing. They also help identify critical areas of a part or component that require specific attention during machining.

Why Do You Need to Prepare Technical Drawings for CNC Machining?

Technical drawings are an essential part of CNC machining. Without accurate and detailed technical drawings, it would be impossible to create the precise parts and components required for modern manufacturing processes.

  • Technical drawings provide a clear and concise representation of the design specifications, including dimensions, tolerances, and material properties. This information is necessary for CNC machines to produce high-quality parts that meet the exact requirements of the end-use application.
  • Providing critical information for CNC machining processes, and technical drawings also facilitate effective communication between designers, engineers, manufacturers, and other stakeholders involved in the production process.
  • Technical drawings serve as a common language that everyone involved can understand regardless of their background or expertise.
  • This ensures that all parties have a clear understanding of what needs to be produced and what quality standards need to be met.
  • Technical drawings for CNC machining help reduce errors and minimize waste in CNC machining operations.

Steps to Draw a Technical Drawing for CNC Machining

Steps of Technical Drawings for CNC Machining

Creating a technical drawing for CNC machining requires precision and attention to detail. A technical drawing is a blueprint that guides the CNC machine in creating the desired product accurately. Without a technical drawing, it would be impossible to achieve quality results with CNC machining.

  • The first step in creating a technical drawing for CNC machining or CNC milling is to gather all necessary information about the product. This includes dimensions, tolerances, material specifications, and any other requirements that must be met.
  • Once you have gathered this information, you can start sketching out your design on paper or using computer-aided design (CAD) software.
  • It’s important to choose the correct scale for your technical drawing. The scale will determine how much space each feature of your product takes up on the drawing sheet.
  • You should also consider adding notes and annotations to help clarify any ambiguous aspects of your design.
  • After completing the drawing you should revise the whole drawing whether there is any mistake or not.

Adding Process of Critical Dimensions in Technical Drawings?

These technical drawings for CNC machining act as a guide for machinists to produce accurate and precise parts. The success of a project depends on the quality of these technical drawings. So, it is crucial to add critical dimensions in technical drawings that accurately represent the final product.

  • The first step in adding critical dimensions is to identify the important features of the part. These features can include holes, fillets, chamfers, and any other critical dimensions that affect the functionality or fit of the part.
  • Once these features are identified, they should be clearly marked on the technical drawing with appropriate symbols and tolerances.
  • It is important to make sure that all dimensions are clear and readable on the drawing. This includes using appropriate font sizes and styles for labeling each dimension. It is helpful to organize related dimensions into groups for easier interpretation by machinists during production.

What Is Geometric Dimensioning & Tolerancing?

Geometric Dimensioning and Tolerancing (GD&T) is a set of symbols and specifications used in technical drawings for CNC machining. It is a language that communicates the design requirements, allowing manufacturers to produce parts that meet exact specifications. The symbols used in GD&T include straightness, circularity, flatness, perpendicularity, parallelism, and position.

GD&T is essential for precision CNC machining because it ensures that parts are produced with the highest accuracy possible. With traditional dimensioning, there can be confusion or misinterpretation of dimensions between designers and machinists. GD&T eliminates any guesswork by providing clear guidelines on how to measure and produce parts within allowable tolerances. This leads to increased efficiency in production processes as well as fewer errors or defects in final products.

What Is the Process of Adding Threads in Technical Drawings?

One crucial aspect of technical drawings is the use of threads. Adding threads to a technical drawing can seem daunting at first, but with the right tools and techniques, it can be a straightforward process. 

  • The first step in adding threads to a technical drawing is determining the thread type and size required for your project. You can find this information in engineering tables or by consulting with specialists in the field.
  • Once you have determined the thread specifications, you need to select the appropriate tool for creating them within your software program. This tool may vary depending on your program’s capabilities, but the most commonly used tools include helixes, sweeps, or revolved cuts.
  • Draw a circle representing the crest diameter of the thread and offset it from the centerline by half of the pitch distance. Then draw another circle representing the root diameter and offset it from the centerline by half of the pitch distance as well.
  • The next step is to draw your thread profile onto your technical drawing using specific symbols and conventions like pitch diameter, minor diameter, major diameter, etc.

How to Add Hole Callouts In Technical Drawings?

Hole callouts indicate the size and position of holes in a part, allowing for accurate drilling and machining. To add hole callouts in technical drawings, you can follow the below steps:

  • Identify the location of the hole on the drawing.
  • Determine the size and type of hole required. This may include factors such as thread type, counterbore depth, or chamfer angle.
  • Once these details are established, use a symbol or abbreviation to represent the hole on the drawing.

Note: There are various standards for hole callouts depending on industry and region. Suppose, ISO 2768-1 provides guidelines for general tolerances that can be used in most countries worldwide. ASME Y14.


Technical drawing for CNC machining is an essential part of modern manufacturing. The drawings provide a visual representation of the parts and components to be made and are used by engineers and technicians to quickly interpret what materials, tools, and processes should be used during manufacturing. Understanding how to read and interpret technical drawings for CNC machining is an important skill for anyone involved in the field of manufacturing.

Posted in: