I have a discussion about Beveled Rectangular Taps going on the AUGI forums, and I didn't want to shortchange all of you on the Autodesk forums, http://forums.augi.com/showthread.php?t=68220.
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.....I figured I'd post a version of this takeoff that I helped build when I was in support.
This one has all sorts of bells and whistles, as I got engrossed with fixing it one afternoon, and my trig hand was strong that day.
It adheres to SMACNA standards OOTB (Takeoff Length = 0.25 * Duct Width, 4" Minimum), but allows you to override both the length and the angle if desired, so this is really all that you need. To accomplish this, there are a bunch of nested IF statements that drive the dimensions, have fun going through it if you'd like.
I actually forgot about this family until I saw this thread, now it's time to get it into the product.
Cheers,
Kyle B
P.S. As this is not an officially released piece of content, it has not been through our QA process. Therefore I cannot gaurantee its behavior on all cases.
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Kyle Bernhardt
Director
Building Design Strategy
Autodesk, Inc.