Sketches form the basis of most model features. For example: a closed sketch region can be used to create a solid extrusion (or cut) in your model while unclosed sketch geometry is often used to extrude a surface. Finding an error in a sketch requires that you understand how each piece of sketch geometry relates to each other piece and that you understand how the sketch will be used to create subsequent model features.

If your sketch includes imported geometry that was originally created by another designer it is often more challenging to identify design errors. Unexpected behavior can often result while using imported sketches due to the way the geometry was created in the exporting system. Common issues include:

• Imported geometry that appears to define a closed region can have small gaps between lines and arcs. These gaps prevent the region from behaving as expected during the creation of a solid feature.
• Lines that appear to be perpendicular may not actually measure 90 degrees. This type of issue will often not become apparent until you attempt to assemble the part while assuming that the created feature has perpendicular faces.
• Autodesk Inventor adjusts the value of any exported dimension to reflect the size of the actual geometry. This type of issue can be problematic in cases where the original designer changed one or more dimensions rather than adjusting the size and position of the geometry.

The Sketch Doctor can help you find problems with open regions. Issues involving incorrect angles or dimensions require closer scrutiny.

Let’s take up a simple example to learn how sketch doctor can be used:

I have created a sketch using line command, as shown below

But as you try to extrude this  sketch, you must get a solid entity. However, as a I select the sketch, I’m not able to select the profile as still it reads select profile when I move inside the loop.

So, now I got panicked and did not know what to do, so I tried a new command available within Inventor from a long time called sketch doctor and activated it by right click RMB in sketch mode

The Sketch Doctor Dialogue box appears,

Now click on Diagnose Sketch, to see the errors . . .

You are now prompted with a Diagnostic Test asking for the following

• Redundant Points
• Missing Coincident Constraints
• Overlapping Curves
• Open Loops
• Self – Intersecting Loops

The Sketch doctor gives you the possible errors on the sketch, My Goodness I see that there is an open loop in the sketch

Now let’s click on next to see where the open loop exist and I see an immediate preview of the open loop with this message in the sketch doctor dialogue box

VN:F [1.8.1_1037]

VN:F [1.8.1_1037]