The difference between Shape feature and Modification feature

What does Shape feature and Modification feature mean? What is the difference between the two and why is it good to know?

IRONCAD is in many ways a unique and versatile CAD system where the user can very often choose which working method is best suited for what needs to be done. Even such a basic function as creating a new extruded shape can be performed in many different ways!

You may think that one or a few ways to create a new feature should be enough, but when you have worked with various different models and projects over time, and there are also lots of different types of users in lots of different industries, it may be easier to understand why there have been more and more ways to do more or less the same thing.

Another unique feature of IRONCAD is the "flexible methodology", a perhaps somewhat unorthodox mix of (non-parametric) Feature- and history-based yet "directly editable" structure that the Innovative Part 3D models are built with. So far, no other 3D CAD system has solved this as seamlessly and smoothly as in IRONCAD.

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Shape feature

A Shape feature is built up from one or more sketch planes to create one of the four "basic geometries" Extrude, Spin, Sweep and Loft that can be created with virtually any type of 3D modeler (CAD, CAM systems, 3D printing etc). A part can consist of one or more Shape features.

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Watch some instructive videos on IronCAD Academy (English language):

IronCAD Academy about Extrude Shape feature: https://ironcad.academy/tutorial/extrude

IronCAD Academy on Spin Shape feature: https://ironcad.academy/tutorial/spin

IronCAD Academy about Sweep Shape feature: https://ironcad.academy/tutorial/sweep

IronCAD Academy about Loft Shape feature: https://ironcad.academy/tutorial/loft

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IntelliShape?

A Shape feature is also called IntelliShape® in IRONCAD. There are several reasons, it is very easy to change the size of a symmetrical Shape feature if you add the differently colored round Sizebox handles, but also the ability to add additional shapes such as radii, chamfers, draft angles and other functions (also called Surface Reshaping Properties) within the same Shape feature, are unique functions to an IntelliShape, which by the way is also a technology patented by IronCAD LLC in the CAD industry.

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Modification feature

Once there is a solid 3D geometry created by e.g. a Shape feature , you can modify its shape with a feature of type Blend, Chamfer, Draft, Shell or Trim. These must be associated (linked) with one or more of the faces/edges/vertexes that build the 3D geometry in question. They can of course also be added to an imported geometry that "only" consists of BRep data(Boundary Representation data). A part can never consist only of a Modification feature.

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See some instructive videos on IronCAD Academy (English language).

IronCAD Academy on Blend Modification feature: https://ironcad.academy/tutorial/blend

IronCAD Academy about Chamfer Modification feature: https://ironcad.academy/tutorial/chamfer

IronCAD Academy about Draft Modification feature: https://ironcad.academy/tutorial/draft-faces

IronCAD Academy about Shell Modification feature: https://ironcad.academy/tutorial/shell-part

IronCAD Academy on Trim Modification feature: https://ironcad.academy/tutorial/trim

Copying a feature with the TriBall

It may be useful to know that you cannot move or copy a Modification feature with the TriBall. The TriBall only works together with Shape features. The reason is basically the same as how they are built. What you copy or move with the TriBall must be able to "stand on its own" and the result when copying or linking with the TriBall will never be associative to anything else, for better or worse.

For example, if you select one or more extrusions, you can activate the TriBall, but as soon as a Blend or Chamfer is also added to the active selection, you can no longer activate the TriBall. This is because the new Blend or Chamfer that would be "created" at the same time must first be associated ("linked") to an ID number of an edge or surface, but that edge/surface does not yet exist.

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Therefore it is necessary to either create a new Blend afterwards or edit an existing Blend and add the new edges that have been created. Then consider the order in the history tree, where IRONCAD can automatically move an existing Blend to the end of the tree structure if necessary. If you have turned off this automatic function called "Part Reordering", you must first "manually drag" your Modification feature in the history tree to be placed after the new Shape features added last in the part.

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Transform features

Since the TriBall does not create any features that have associations with edges/surfaces, it is good to know that there are alternative tools to the TriBall when it comes to creating linked patterns of features or if you want to mirror one or more features, which also creates an associative link between the original and the copy.

The tools for these are Pattern feature, Mirror feature and Scale Body and appear in the Transform group under the Ribbon tab. Feature. More on these below.

"Parent-Child"

These features are based on a principle that in classic CAD language is called a "Parent-Child" relationship (the phrase "Master-Slave" is sometimes also used). The disadvantage of this principle is that there is no possibility to change the shape of individual "Children-features", you can only change their "Parent-feature", and they can only "exist" as long as their "Parent-feature" is also present. If it is removed or for some reason stops working, its "Children-features" will also stop working.

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TriBall does not use the "Parent-Child" principle.

It is important to note that it would never happen that features created by the TriBall would disappear for the same reason, because no such "Parent-Child" relationship is ever created. Also, new features copied or linked via TriBall can never be associative to any other features. Linked features via TriBall are of course associative to each other in shape, but they are never (cannot be) associative in position to another edge or surface.

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Instead, the position of a Shape feature is mainly controlled by the position of its Anchor Point in XYZ space (however, the Anchor Point can also be associated with a surface through a setting, a kind of "light constraint"). Another important difference is that "you can" change any of the linked copies created with TriBall, as there is no " Parent-Child" relationship. They are rather in a kind of"Equal-Twins" relationship.

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More about different Transform features

Pattern Feature

With Pattern feature you can create linear, circular, edge or point controlled patterns with features that follow selected points, an edge or an axis to rotate around. If the position or shape of the points, edge or axis changes, the pattern will be forced to adapt (associatively) to that change. It is not possible to create a similar function with the TriBall Pattern.

IronCAD Academy about Pattern feature: https://ironcad.academy/tutorial/pattern-feature

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Mirror Feature

With Mirror feature you create a mirrored geometrically linked copy around an edge or axis that, in a similar way to a Pattern feature , is associative with the selected object. If the edge or axis is moved or otherwise changed, the mirrored copy is forced to adapt to the change. It is possible to mirror features also with TriBall Mirror, but the difference is that the mirrored copies with TriBall cannot get the same kind of associativity to other geometries.

IronCAD Academy on Mirror feature: https://ironcad.academy/tutorial/mirror-feature

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Scale Body

Med Scale Body allows you to scale up or down selected parts, or a Body in a Structured Part, by a certain scaling factor. If features in the part change their shape, the scaling effect will adjust the final result. Changing the scale of a shape can also be done with the Sizebox handles on a feature, it is even possible to bring up the Sizebox handles on a part or a assembly and thus change the scale on them as well!

IronCAD Academy about Scale Body: https://ironcad.academy/tutorial/scale-body