Autodesk Inventor – Back to Basics - Sketched centrelines for revolved bodies

By Chris Smith

Introduction
When creating revolved bodies we need to provide a sketched line to the tool for a revolution axis. A sketched line or even a model edge can be used for this and in most cases suits the task. There is a tip when creating you revolution sketches that can make this process faster, easier and allows additional options.

Example
In this example I am making a simple O-ring that we can use to create a component family using an iParts table. First of all, we need a sketch of our O-ring profile and the rotation axis.

Using the sketch above and selecting the Revolve tool we get the options below. The software has accepted the cross section circle as a profile as it is the only closed loop, but it still asks for a rotation axis.

Clicking the vertical line that we sketched will finish the tool inputs and will create our O-ring and we can use these inputs as the parameters for our iParts table.

The process that we have just followed will create the result that we are looking for, but there are a couple of improvements that we can make to help save us time creating our model family. The main issue here being that the inside diameter value must be halved for the revolution.

Let’s rewind back to the point where we created our sketch and change the line type of the vertical line from a solid line to a centreline.

The other change we need to make to the sketch is to delete the inside radius dimension and reapply it.

By adding a dimension to a centreline, the software changes the dimension to a diameter value, meaning we no longer need to create the equation in our parameter. Next, we can finish the sketch and start the revolve tool.

This time the tool automatically selects the rotation axis and the profile as there is a single centreline and a single closed profile.

We can also see from the image above that the inside diameter is the full value and not halved meaning we can now copy values from a standard O-ring table without having to add in the addition calculation.