By default Autodesk Inventor will dimension the Radius of an Arc in a sketch. So how do you find the Length of the Arc? And what if you want to specify the Arc Length to drive your sketch?
Measuring the length of an Arc in an Inventor Sketch is easy. Just use the ‘Measure Loop’ tool.
Inspect Tab > Measure Panel > Loop
But this won’t allow you to use the Arc’s length in Parameter’s and Formula’s.
A Parametric Arc Length?
Unfortunately Inventor doesn’t have an ‘Arc Length’ type of Dimension Parameter in sketches. But it is pretty easy to grab the length of an Arc using a Formula.
To Get the Length of an Arc
To get the Length of an Arc to use in your Equations you will need:
- A Model Parameter for the Included Angle of the arc – Angle
- A Model Parameter for the Radius of the arc – Radius
- A user Parameter for the Arc Length – Arc Length
- A User Parameter to convert Degrees into Radians – Radians
The Formula is:
Radius * ( Radians / 1 rad )
To Drive the Length of an Arc
To drive the Length of an Arc you will need:
- A Model Parameter for the Included Angle of the arc – Angle
- A Model Parameter for the Radius of the arc – Radius
- A user Parameter for the Arc Length – Arc Length
The Formula is:
ArcLength * 180 deg / ( Angle * PI )
Visual Feedback
If you want visual feedback of the Length of the Arc you could add some sketch text, and pull in the Value you are looking for.
Annotating an Arc’s length in an Inventor drawing
You can add a dimension annotation in an Inventor drawing to give the length of your arc using the ‘General Dimension’ tool.
Annotate tab > Dimension Panel > Dimension Tool
Inventor will automatically pick the radius of the Arc. Just right click to get the ‘Length’ option.
The Final result will look like this:
I hope that you enjoyed this sketching tip!
Read this post to find out my Top Tip for creating Inventor sketches ‘Sketching – Keep it simple‘.