Forums >> Revit Building >> Technical Support >> Complex Family Design: Properly Cut Rafters in Beam Systems

NMODIE

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Joined: Tue, Oct 27, 2009
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Hey folks. I'm working on creating a family that can be used in the stuctural beam system interface, more or less so that I don't have to spend the couple G's on Rafter+. The aspect that's got me hung up at this point is how I can retrieve parameters from something (like a roof) so that the beam is properly cut at the ends. When you create a family from the structural beam or brace template, it's all based on a level reference plane, and the end cuts are perpendicular to that selection. What I want to do is to be able to create a beam system on a particular work plane (the face of a roof) and have the family understand that that work plane has a slope, and to make the cuts vertical in spite of that slope.

I really hope that someone understands me despite my totally convoluted language. If I get this to work it could be really sweet, and I'd be happy to share it with whomever. If you ask me questions about what I'm getting at here, I might be able to disambiguate.

Thanks,

Noah

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jlights

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Joined: Tue, Dec 18, 2007
146 Posts

I don't do structural but I do a lot of families, so I believe I get what you are asking. The base of your family is going to be on a sloped surface but you need the other end of the beam to cut vertically in space (not parallel to the workplane it is placed on). I don't know if this idea will work, but you might try creating a void extrusion in your beam family with a length offset (so the beam can be the right length before cutting) and a rotation parameter that will allow you to create the cut at the right angle. I don't think that there's a way for the rotation angle parameter to read the angle of the workplane the beam is on and calculate the correct cutting angle at the other end; you'll probably need to type in the cutting angle you want. Or better yet, you could make several beam types for various roof slopes and set the appropriate cutting angle for each type in the family. Then you would just have to give each beam a length when placed in the project.

Unless you can find a way to flex the angle of the cutting face of your void extrusion, you will probably have to make the void as a separate nested family in order to be able to rotate it; then you align the nested void with a reference LINE in the beam family and control the angle of the LINE with the angle parameter. But I don't know whether voids in a nested family will cut an extrusion in the host family. HTH. Good luck!

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jlights

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