Forums >> Revit Systems >> Technical Support >> Need assistance building a reducing tee family in MEP 2011

jfmonod

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Joined: Mon, Apr 23, 2007
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Hi,

 I am attempting to build a reducing tee welded pipe fitting and am having a little trouble with the existing text file lookup table.

 More to the point, I am starting from the out-of-the-box "Tee Reducing - Threaded - MI - Class 150" and am trying to get this to resemble the fittings shown in the attached PDF. After removing the bands and all associated parameters, I am running into trouble reconciling the "Center to End" parameters with the C and M dimensions shown in the PDF table.

Replacing the values in the CSV file isn't coming close to the sizes given and I don't seem to be unable to edit the following :

text_file_lookup(Lookup Table Name, "CtE1", 0.29 * Nominal Diameter 1 - 0.05 * Nominal Diameter 2 + 0.52 * Nominal Diameter 3 + 0'  0 181/256", (Nominal Diameter 1), (Nominal Diameter 2), (Nominal Diameter 3))

 without ending up with an "invalid number of arguments". 

 If anyone can shed some light here I would greatly aprreciated it.

 Thanks

 JF

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jfmonod

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WWHub

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Hey come on jfmonod - share.

We ask everfyone who answers their own question to post the answer so others can benefit.  Sharing information is how this forum works.

So... please post the answer.

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jfmonod

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Ok. How to create a Reducing Tee fitting for people who don't know jack about pipes .... (like me)

First off is understanding how Lookup Tables work. My problem was twofold: 

1. I was trying to reverse engineer an existing fitting and modify it. Lookup tables don't deal with this very well apparently. I added a couple of parameter fields to the csv file and rebooted revit and the result was an "Invalid Formula" or similar error every time I tried to implement these fields in the Family Types panel. It drove me mad.

 So I rebuilt the geometry from scratch with a fresh set of parameters and a new Lookup Table built from the data on the Taylor Forge welded fittings sheet I attached to this post.  The following blog post and the accompanying Whitepaper were very helpful   http://inside-the-system.typepad.com/my_weblog/2008/11/revit-mep-text_file_lookup-and-lookup-tables.html

2. I was having difficulty in defining the "Not in the Table" parameter (in the example in my question that's    0.29 * Nominal Diameter 1 - 0.05 * Nominal Diameter 2 + 0.52 * Nominal Diameter 3 + 0'  0 181/256" )

 I haven't got a clue where that formula came from in the original fitting, but I substituted it in each case by plotting a graph of the relevant dimensions of each fitting size in Advanced Grapher (http://www.alentum.com/agrapher/) and extracting a likely linear formula  with regression analysis. PDC is good enough for me. 

 The end result is the family which I am attaching now to this reply. Not all sizes are included in the csv file. We only needed 2" - 12" and I am told that nobody uses 3.5". Anyway any comments, improvements etc... are welcome. I will be following up with an eccentric reducer and a concentric reducer from the same manufacturer (same pdf sheet).

 JF

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oval to round tee fitting family

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NEED HELP WITH AN MEP FAMILY, NEW TO THIS, I HAVE TWO QUESTIONS.

2