What are Technical Drawings? Everything you need to know.

In the world of CNC machining manufacturing and engineering, there’s no room for ambiguity. A single miscommunication can cost time money, and even compromise safety. That’s where technical drawings come into play—a universal language that ensures everyone, from designers to shop floor technicians, is on the same page.

 

So, what are technical drawings? These are specialized, standardized diagrams that clearly represent a product’s design. They encompass every minutiae, from dimensions and materials to assembly instructions, effectively serving as a project’s blueprint.

 

Interest piqued? Good. Stick around as we delve into this fascinating subject, which is at the core of our operations here at Worthy Hardware.

Types of Technical Drawings

The world of technical drawings is not a one-size-fits-all affair; it’s more like a tailored suit—each type serving a specific role and suiting a particular need. Let’s break them down:

• 2D Drawings: These are the granddaddies of technical drawings. They represent an object in two dimensions: width and height. Simple, but they get the job done, especially for less complex projects.
• 3D Models: Welcome to the modern age! A 3D model adds the z-axis into play, offering a fuller, more complete visualization of the object. Often digitally rendered, these models can be interacted with, rotated, and dissected. They’re crucial for complex machinery or for getting a real “feel” for the object.
• Isometric Drawings: These are the illusionists in the drawing world. At first glance, they appear 3D, but they’re a 2D representation showing the object from angles where the x, y, and z axes are equally foreshortened. They offer a comprehensive view without getting into the nitty-gritty details.
• Orthographic Drawings: The orthographic drawing is like the multi-angled view you get when customizing a car online. They offer multiple 2D views—typically front, top, and side—to give you a fuller understanding of the object’s dimensions.

I highly recommend our whitepaper on Exploring the Varieties of Technical Drawings for anyone seeking to delve deeper into these types.

Why are Technical Drawings Important in CNC Machining?

Accuracy and Precision

In the CNC machining world, where a millimeter can make all the difference, accuracy and precision are not just lofty ideals but non-negotiable requirements. Technical drawings, crafted to the highest standards, offer this level of exactitude. For instance, where we operate in CNC machining, missing the mark is not an option. The detailed dimensions and specifications in technical drawings ensure we always hit the bullseye.

Communication across Teams

Let’s face it; words can be imprecise. What does “a little to the left” even mean? Technical drawings are the ultimate communication tool, erasing ambiguity and ensuring everyone from the design team to the shop floor knows precisely what they should be doing. In complex sectors like aerospace or automotive manufacturing, this clarity isn’t just helpful; it’s essential.

For more insights into the role of technical drawings in inter-departmental communication, refer to our exclusive study, Bridging Communication Gaps in Manufacturing with Technical Drawings.

Regulatory Compliance

Have you ever heard of the butterfly effect? One slight deviation in a design can have a ripple effect, leading to catastrophic outcomes. This is especially true in highly regulated industries like medical and military applications. 

Technical drawings offer a structured way to adhere to international and industry-specific regulations. These documents become particularly crucial during audits, providing a clear compliance record with quality standards like ISO 9001 or AS9100.

What You Could Find in Technical Drawings?

Title Block

Before diving into the technicalities, look at the title block, usually found at the bottom right corner of the drawing. This section provides essential information such as the drawing title, drawing number, who approved it, and when it was approved. The title block is your introduction to the world the drawing represents.

 

Isometric Views

An isometric view is often included to give you a 3D object representation. It helps to visualize how the end product will look, offering a comprehensive argument in one shot. If you want to get the “big picture” quickly, you’ll find it here.

Our research paper, Isometric Views: The Visual Language of Technical Drawings, is a must-read for a deep dive into understanding isometric views in technical drawings.

 

Orthographic Views

These are your bread-and-butter 2D views, showing the object from the front, top, and side. They may not offer the depth of a 3D model or an isometric view, but they provide the most critical measurements and angles. This is where the rubber meets the road for most manufacturing tasks.

 

Auxiliary Views

Sometimes, more than the standard front, top, and side views are needed to capture more complex features. This is where auxiliary ideas come in. These are additional views taken from an angle not ordinarily used to show features more clearly.

 

Section Views

Have you ever wondered what’s inside a complex machine or a building? Section views offer this internal perspective by showing a cut-away portion. It’s like having an x-ray vision for your project.

 

Detail Views

They say the devil is in the details, and it’s no different in technical drawings. Detail views zoom in on specific aspects of an object, offering a closer look at intricate features. These views often come with additional notes or dimensions that wouldn’t fit in the standard views.

 

For more information on leveraging detail views for manufacturing excellence, consider our whitepaper, Detail Views: The Fine Print of Technical Drawings.

 

Notes for Production

These special instructions or recommendations are crucial during the manufacturing or construction phase. They may include material specifications, finish types, or any other special instructions that don’t fit neatly into the drawing.

 

Coordinates

Finally, coordinates are often included to provide exact positional information. This is particularly vital in CNC machining and other automated processes, where pinpoint accuracy is required.

How to Create a Technical Drawing?

Sketching vs. CAD

Ah, the age-old debate: manual sketching or Computer-Aided Design (CAD)? Both have their merits, but let’s be honest: CAD is often the faster and more reliable choice in a world where time is money. However, wait to write off sketching; it’s still a fantastic tool for conceptualizing ideas.

In the early days, manual sketching was the go-to method for drafting technical drawings. These sketches were crafted with meticulous attention to detail, often using tools like T-squares, compasses, and protractors. The charm and tactile experience of drawing by hand is unparalleled but, let’s face it, not the most efficient. Errors are frequent, and changes could be more convenient.

Enter CAD, the modern answer to all these challenges. The transition from sketching to CAD wasn’t just a technological leap but a paradigm shift. CAD software allows for rapid iterations, precision, and, most importantly, easy modifications. Plus, the added benefit of 3D modeling gives a far more comprehensive view of your project than a 2D sketch ever could. In sectors like aerospace, medical devices, and indeed, in our world of CNC machining, CAD is indispensable.

For a closer look at this transition and its impact on technical drawings, you might find our report, From Sketch to Screen: The Evolution of Technical Drawings, particularly enlightening.

So, should you go for sketching or CAD? Well, it’s not an either-or question. Initial sketches can provide a quick way to jot down ideas and brainstorm, while CAD can turn those ideas into viable, precise, and shareable designs. The future of technical drawing is not a tug-of-war between the past and the present; it’s an amalgamation of both.

Essential Tools and Software

When diving into the intricate world of technical drawings, the right set of tools can make or break your project. In today’s modern landscape, CAD software is king, but other hardware and accessories also play pivotal roles in streamlining the process.

Here’s a tabulated overview of essential tools and software for your convenience:

Tool Category	Popular Choices	Usage Context	Recommended For
CAD Software	AutoCAD	General 2D and 3D modeling	Engineers, architects
	SolidWorks	Mechanical design, 3D modeling	Mechanical engineers, manufacturers
	CATIA	3D CAD design, highly specialized	Aerospace, automotive sectors
	SketchUp	Architectural and interior design	Architects, interior designers
	Fusion 360	Integrated CAD, CAM, and CAE	Small to mid-sized businesses
Digitizer Tablets	Wacom Tablets	Tactile drawing experience	Designers, artists
3D Mice	3Dconnexion SpaceMouse	Navigate 3D models	3D designers, engineers
High-Resolution Monitors	Dell Ultrasharp, Apple Pro Display XDR	Clear visual output	Anyone working on detailed designs
Laser Scanners	Faro, Hexagon	Reverse engineering, quality assurance	Manufacturers, quality control experts

For a more detailed analysis of each tool’s pros and cons, refer to our in-depth guide, Choosing the Right Tools for Technical Drawings.

Steps in Making a Technical Drawing

Creating a technical drawing isn’t just about sitting down and drafting. It’s a meticulous process that involves multiple steps, each crucial in its own right. Here’s how to go from a blank canvas to a detailed, accurate technical drawing that can be used in any professional setting.

Step 1: Conceptualize the Design

Before thinking about drawing, understand what you’re trying to create. Are you designing a mechanical part? An electrical layout? Knowing your end goal will guide the entire process. Often, this stage involves rough sketches or brainstorming sessions.

Step 2: Select the Right Tools

Choose the CAD software or manual drawing tools that best fit your project’s needs. The tools should offer the necessary features for your specific type of technical drawing.

Step 3: Set Up the Drawing Environment

Whether setting the scale in a CAD program or choosing the right type of paper for manual drawing, setting up your environment correctly is crucial for accuracy.

Step 4: Draft the Basic Outline

Start with the foundational elements of your drawing. This could be the basic shape of a mechanical part or the main lines in an architectural plan. Make sure these are drawn to scale.

Step 5: Add Details

Dimensions

When it comes to dimensions, there are several vital elements to consider. The first is units of measure. Are you working in metric or imperial units? This decision will affect everything from the drawing scale to the dimensions themselves.

Also, keep in mind dimensional tolerances. This specifies the allowable variation for the dimension. For example, a rod that needs to be 10mm in diameter might have a patience of +/- 0.01mm. This tight tolerance ensures the part will fit strictly as intended in the final assembly. Manufacturers rely on this level of detail to understand how precise the fabrication needs to be.

Moreover, there’s the dimensional chain. It’s not enough to specify the dimensions of individual parts; you need to indicate how they relate. For example, in a complex assembly, you might need to fix that Hole A should be exactly 100mm from the edge, but also that Hole B should be exactly 50mm from Hole A. These are called relational dimensions, and they’re crucial for intricate assemblies.

Annotations

Annotations are more than just side notes; they’re an integral part of the drawing. These should be written in a standardized format as per industry norms. Special attention must be given to the font size and style so that they are easily readable yet unobtrusive.

Annotations should explain what a part is and how it interacts with other factors. Is it welded? Bolted? Does it need to be removable, or is it permanently affixed? This kind of information can be vital during the assembly process.

Additionally, material specifications should be annotated. The materials from which a part is made can have significant implications for its strength, weight, cost, and manufacturability. For example, specifying that a part should be made from 316L stainless steel as opposed to generic stainless steel could be critical for applications that require resistance to chemical corrosion.

Geometric Tolerances

Geometric tolerances are critical in defining how individual parts will fit and function within an assembly. These are conveyed through Geometric Dimensioning and Tolerancing (GD&T) symbols. The symbols are a standardized way to communicate complex geometric tolerances in a concise manner.

For example, you may use the ‘Flatness’ symbol to specify that a surface must lie within a specific flatness range, ensuring that it will mate properly with other parts. Another commonly used GD&T symbol is ‘Concentricity,’ which ensures that one feature in part is centered with another. The application of these geometric tolerances will vary depending on the part’s intended function. Properly applied, geometric tolerances can significantly reduce manufacturing costs by allowing for more lenient dimensional tolerances where precision is not critical.

Callouts for Special Features

Callouts are precise annotations indicating special instructions or notes for a particular feature. They are often placed in a dotted or dashed box and point directly to the part they refer to.

For example, a callout might specify a proprietary or specialized surface treatment like anodizing or plating. It could also indicate a requirement for additional inspections or tests to be performed on a feature, such as a hardness test for a metal part that will be under heavy load. The nature and format of these callouts will often adhere to industry-specific standards. Please comply with these to ensure that parts are in specification and even usable.

Multiple Views and Cross-Sections

A single view is often insufficient for complex parts to capture all the necessary details. Multiple views like top, side, and isometric may be required in such cases. Cross-sectional views can also be invaluable for showing the internal features of a part.

In a cross-sectional view, imagine the part being cut in half along a particular plane and then displaying the “exposed” picture. This helps in understanding how the internal components align with the external features. The cross-section planes should be clearly labeled, and the view should include all the relevant dimensions and tolerances.

Revisions and Change Management

Lastly, a proper technical drawing often includes a revision block or table. This is used to track any changes made to the picture over its lifecycle. Each shift is usually accompanied by a revision number, date, and the name of the person who made the change. This is crucial for quality control and accountability.

Surface Finish Symbols

Surface finish symbols indicate the texture or finish a machined surface should have after manufacturing. This is crucial when the surface finish can significantly impact the part’s functionality. For instance, moving parts often require smoother finishes to minimize friction. In contrast, rough finishes may be suitable for surfaces that need to be adhered to or coated.

Weld Symbols

For parts that require welding, specific symbols are used to indicate the type of weld, its size, and other related instructions. Whether it’s a full or partial penetration weld, the characters provide a shorthand way of conveying this information. Like other annotations, weld symbols adhere to industry standards, ensuring everyone involved in the fabrication process understands the specifications.

Balloons and Bill of Materials (BOM)

You’ll often find numbered “balloons” tied to each component in assembly drawings. These numbers correspond to a Bill of Materials (BOM), usually found on the same drawing or a connected document. The BOM provides additional information, such as part numbers, descriptions, quantities, and material specifications for each component. This offers the dual benefit of making the drawing more straightforward to read and providing a detailed inventory for manufacturing and assembly.

Fastener Details

The types, sizes, and locations of fasteners like screws, bolts, and rivets should also be indicated. This may include torque settings for bolts or the specification of whether a permanent fixing method like riveting is required. A misstep here could compromise the final assembly’s structural integrity, so ensure this is clearly and accurately marked.

Step 6: Review and Revise

Don’t assume your first draft is your final draft. Review your drawing for any errors or omissions. This step may involve other team members, including engineers, architects, or quality assurance professionals.

Step 7: Add Final Touches

If applicable, incorporate any feedback received during the review stage and add final touches like shading or color coding.

Step 8: Validation and Approval

Before your drawing can be used in a production environment, it must go through a validation and approval process. This ensures the drawing meets all quality and safety standards.

Step 9: Save and Archive

Save your work in the necessary format. CAD files, for instance, can be saved in different forms. DWG, .DXF, or.STL, depending on what the project requires. Permanently archive your work for future reference or modifications.

Conclusion

For those who aim for something other than precision and efficiency in CNC manufacturing, mastering the complexities of technical drawings is non-negotiable. The devil is indeed in the details, but as experts in this field, we thrive on those details to deliver products that meet and exceed customer expectations.

For more resources and tips on creating impeccable technical drawings, you’re welcome to check our extensive library of guides Worthy Hardware