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5 Common Mistakes to Avoid When Designing in NX CAD
9 Nov, 2023


Engineers depend on CAD modeling because it supports design and manufacturing stakeholders from concept to manufacture, laying the groundwork for product development process. Making mistakes during the design process can take a lot of time for the designer to correct, or it may require extra time when updating the simulation at a later point.

Here we share some common mistakes that one should avoid.

1. Creating a variety of sketches on the same plane

Using a variety of sketches on the same plane to represent its geometry is one of the most typical mistakes made by beginner designers. A “master” sketch should be created, where all the information will be described and constrained, rather than using for example three sketches to define the basic shapes that will be used as the foundation for features. Usually, this occurs when you don’t begin your designing process without a defined design intent. When this is done frequently, the model tree becomes congested, making it difficult for another user to easily comprehend, modify and update the model.

Figure 1: One sketch for model creation.

Figure 2: Multiple sketches for model creation.

Figures 1 and 2 show the same drawing lines, with Figure 1 requiring only a single sketch while Figure 2 requires two sketches on the same plane.

2. Using plenty of features instead of one

When establishing numerous features when they can be combined into one, the prior error might occur as well.

For instance, since all the edges marked in Figure 3 have the same radius, a single blend feature is applied to all of them. This level of cleanliness in the model tree should be the objective.

Figure 3: Applying a single blend feature.

3. Not fully constraining or over constraining sketches

The third most common mistake is not constraining desirably your sketch by either over or under-constraining. Sketches need to be fully constrained so that no issue is generated during a model update. Why is that though?

When you under-constrain a sketch, you allow some degrees of freedom in your model to exist. This is a crucial phase to watch out for if your final objective is a well-defined product leaving no space for unintentional alterations. While applying a change in one of the defined parameters, leaving some curves, lines, or arcs without a dimension, could radically alter the shape of your model, taking considerably longer to undo it.

When a constraint you intend to apply conflicts with other constraints or dimensions on the sketch object, this is known as over-constraining. As a result, one or more constraints end up being dependent. Think of a straightforward situation when this would be problematic. Imagine trying to edit a parameter with a different value while a sketch is over-constrained; the additional constraints prevent the modified value from being implemented.

Figure 4: Under-constrained sketch.

Figure 5: Over-constrained sketch.

As seen in Figure , the small rectangle is not fully defined, therefore the lines are colored with a light brown to indicate the movable parts. On the contrary, in Figure 5, the model is over constrained, and the parameter cannot be edited.

4. Adding blends before finishing the concept design

A fourth common mistake is the order of the features in the model. Detail features like edge or face blend and chamber change the shape of the model, smoothening geometry edges and creating new ones in their place. If a blend is applied before the main body of the model is complete, the designer has failed to apply proper design intent and will also not be able to use the right edges as a reference for the rest of the remaining foundation features.

5. Not backing up and saving your work

Fifth but not least, is not backing up and saving your work regularly and properly. CAD software can crash, freeze, or corrupt your files, especially if you are working with large or complex models. Losing your work can be frustrating, costly, and time-consuming. To avoid this mistake, make sure you save your work frequently and in different locations, such as local drives, cloud storage, or external devices.

Considering all this, maintaining a model optimal while making it simple for other designers to comprehend can be done by paying close attention to a few crucial details.

At FEAC, we trust that this blog post has been informative and beneficial to prepare top-notch Digital Twins. Should you have any inquiries and questions, please don’t hesitate to reach out to us at support@feacomp.com.


E Elisavet Oursoula Kavoura – CAD Designer at FEAC Engineering
Mechanical Engineer M.Sc
e-mail: e.kavoura@feacomp.com
LinkedIn Profile: Eliza Kavoura