Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool)

kristian_oa — Tue, 24 Feb 2026 03:24:39 GMT

Hello,

I am trying to create a sketch onto a face within a part, which I will then add/modify features from, however I am unable to create a 2D sketch onto any desired face as I am given an error upon running Sketches.Add().

This part is currently an immediate child of the active assembly, but I have also attempted in modifying a part within an assembly, which itself is within the active assembly (a part within a sub-assembly).

To simplify my debugging process, I decided to replicate the "Start 2D Sketch" tool and select a specific face I want to create a sketch onto. Code snippets for this are below:

iLogic Sample:

Dim face As Face = ThisApplication.CommandManager.Pick(SelectionFilterEnum.kPartFacePlanarFilter, "Select a face") ' Only attempt to add a sketch if the selected face belongs to a part If (face.Parent.ComponentDefinition.Type = ObjectTypeEnum.kPartComponentDefinitionObject) Then Dim def = face.Parent.ComponentDefinition Dim sketch As PlanarSketch = def.Sketches.Add(selection) End If

C# Sample:

Face selection = (Face)Globals.InventorApp.CommandManager.Pick(SelectionFilterEnum.kPartFaceFilter, "Select a face"); // Only attempt to add a sketch if the selected face belongs to a part if (((Face)selection).Parent.ComponentDefinition is PartComponentDefinition def) { PlanarSketch profile = def.Sketches.Add(selection); }

Both of these snippets fail upon adding the sketch the part's component definition.

What am I doing wrong?

To my understanding, you can only create a sketch profile on a planar face that resides within its part. But the code above is accessing the component definition of the face as it's parent, ensuring that I am getting the correct component definition for the face.

Are faces not suitable for sketches? In Inventor's built-in "Start 2D Sketch" tool you can select a face on some geometry to create a sketch onto.

Any guidance into understanding why I cannot add a sketch to a face of a part would be greatly appreciated.

Re: Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool)

JhoelForshav — Tue, 24 Feb 2026 11:01:34 GMT

Hi @kristian_oa
Quick fix:

Dim face As FaceProxy = ThisApplication.CommandManager.Pick(SelectionFilterEnum.kPartFacePlanarFilter, "Select a face")

' Only attempt to add a sketch if the selected face belongs to a part
If (face.Parent.ComponentDefinition.Type = ObjectTypeEnum.kPartComponentDefinitionObject) Then
	Dim def = face.Parent.ComponentDefinition
    Dim sketch As PlanarSketch = def.Sketches.Add(face.NativeObject)
End If

When you pick a face in assembly environment it's actually not a face but a faceproxy (the face represented in context of the assembly). Therefore, use face.NativeObject to get the face in the parts context 🙂

Re: Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool)

kristian_oa — Tue, 24 Feb 2026 20:47:46 GMT

Thank you so much for this!

I completely forgot proxies exist and are to be used in these scenarios. You're a legend!

topic Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool) in Inventor Programming Forum

Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool)

Re: Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool)

Re: Create Sketch Fom Selected Face (Replicate "Start 2D Sketch" tool)