Dynamic Block Action vs Dynamic Block Parameters

We have created an AutoCAD column block by using two methods: using dynamic block actions and using parametric features (geometric and dimensional constraint). So what’s the difference? Why we should use parametric instead of dynamic block actions? It looks like using action is easier than using parametric design.


    1. Dynamic block actions are basically AutoCAD tools that we used in conventional AutoCAD drawing. We stretch, scale, move, or mirror our objects.
    2. Parametric is maintaining the objects geometry (using geometric constraint) and control the object sizes (using dimensional constraint). They are different in many ways.

For simple objects like rectangular column, dynamic block actions maybe easier. But when you need to maintain complex objects relationships then you may want to consider parametric features.

Let’s take this profile as an example. It’s almost impossible to control the profile sizes using dynamic block actions. I don’t think we can do that.


By using parameters, we can tell AutoCAD how we want those objects related to each other.

profile parameters

It may look scary, but it’s not difficult. Just a repetitive task and some logic applied. Further more, we can add some calculation expression to relate those objects further.

And sure, we can create a table just like lookup table in dynamic block action.

block properties table

We can choose the sizes we defined in the table, from a drop down list.

profile sizes

My profile is maintaining the relationship between other geometry objects. No matter which size I choose.

final profiles

Sure, we can use stretch action to change the profile size. But we can’t define every geometry sizes. Dimensional constraint can do that.

using strecth action

*Do you realize that there is no radius/diameter parameter in block authoring palettes?

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  1. says

    Thanks Orhan. Honestly I don't know how we can make use of parameters better than in reusable contents. Maybe in other industries there are many things we can do with parameters, especially in manufacturing. But in AEC, I don't think there are many thing we can apply this parameters…