Steven Debooy, a fellow blog reader, recently asked me if it was possible to add a parameterized void at the end of a beam to cut it at a slope. That question prompted me to write this post about how one can achieve that result.
a) Adding a void to the beam is a possible solution. I posted a family in the Structural AUGI forums in 2007. Feel free to reverse engineer it and find out how it works. My example has 2 voids instead: one handles positive angles and the other handles negative angles. The user inputs an angle in one parameter, and 2 calculated parameters evaluate that input and return the correct result.
b) In the 2009 Revit family of products, one can use the Opening by Face tool to achieve the same result. Using this tool to cut the end of a beam, one will get a warning stating that "Opening partially cuts its host". It's not a serious warning (I guess), but it is meant to inform the user that something could potentially be wrong, as usually an opening is meant to have beam material surrounding the entire sketch perimeter! This is the best option if you want to create custom shaped cuts on the fly.
This method makes me mad. Why? Because it's only available in Revit Structure (come on people!). NOTE: As of the Subscription Advantage Pack, this functionality is also available in RAC2010. Thanks Factory! Aaaanyway, You can sketch a reference plane and then use the Cut Geometry tool to trim the beam against the reference plane (actually you can also trim against a grid). Non-linear cuts are not possible with this technique.