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michaelmead
Posts: 296
Registered: ‎03-02-2012
Message 1 of 26 (249 Views)
Accepted Solution

Linear frustration

249 Views, 25 Replies
01-29-2014 05:49 PM

Hello, I am trying to get a linear family to flex incrementally to certain distances. I have written the equations and everything seems to flex fine in the family. But as soon as I load it into the project, It completely ignores my equation driven parameter? I have a feeling that it has something to do with the way a linear family is set up since I cannot delete the length parameter. Its really strange and illogical how it is behaving. I have attached the family. Please help!

The Family is working "properly" in the Project Environment according to the Family. When you draw a linear Family in the Project, that determines the value of the "Length" Parameter in the Family. Since your Extrusion is constrained to the "Length" Parameter in the Family, your formula is being bypassed. You will need to create and additional set of vertical Reference Planes (left and right sides) that will be constrained by the "LengthCalc" Parameter, and then adjust the Extrusion and the Array to be constrained to those Reference Planes instead.

 

You will need to adjust your "Number of Holes" formula to reference "LengthCalc" instead of "Length". Also, your "Length Input" parameter currently holds no power - set the formula to "=Length" or substitute "Length" for "Length Input" in your primary formula and then remove "Length Input".

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Littlebluedog
Posts: 41
Registered: ‎01-20-2011
Message 2 of 26 (213 Views)

Re: Linear frustration

01-30-2014 10:31 AM in reply to: michaelmead

I put the family in and it looks like it stretches okay. Is it supposed to only expand in increments equal to the "Length of a Single Hole Cut".

Yay I'm talking about Revit and stuff
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Steve_Stafford
Posts: 233
Registered: ‎08-16-2007
Message 3 of 26 (207 Views)

Re: Linear frustration

01-30-2014 05:54 PM in reply to: Littlebluedog

Sorry, you won't be able to achieve what you are describing. It sounds like you are seeking the behavior of dynamic blocks in AutoCAD? The stretching action in Revit will always be arbitrary initially but if your formulas are well defined the family will adjust to be only an acceptable size afterward. You just won't get the notched or stepped sort of context you are looking for.

My other older self here: http://forums.autodesk.com/t5/user/viewprofilepage/user-id/46056
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Alfredo_Medina
Posts: 2,865
Registered: ‎06-11-2009
Message 4 of 26 (195 Views)

Re: Linear frustration

01-31-2014 06:23 AM in reply to: Steve_Stafford

To the OP :

 

Maybe you need to change your plan. My comments:

 

1) It is not a good practice to array an extrusion. You should array a nested element instead.

2) It is not a good practice to put so many voids in a family. (Is it really necessary that the elements are voids? They could be just a representation with model lines (nested).

3) If you want a family to have a certain length that is determined by a certain module, make it be driven by an integer parameter that controls the number of elements in the array.

 

Items # 1 and # 2 affect the performance of the family. Have you noticed how long it takes for this family to load and regenerate when you create one instance? Do you want your projects to have their performance affected, waiting for instances of this family to finish regenerating?

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michaelmead
Posts: 296
Registered: ‎03-02-2012
Message 5 of 26 (184 Views)

Re: Linear frustration

01-31-2014 07:06 AM in reply to: Littlebluedog
Yes it is so that the Unistrut can only be cut in between the holes. But when you say it stretches ok, do you mean in a project? or just in the family. Because thats what I found too. In the family I can get it to stretch fine but in the project it follows some other rules for some reason, and doesnt work. Thats my question.
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michaelmead
Posts: 296
Registered: ‎03-02-2012
Message 6 of 26 (185 Views)

Re: Linear frustration

01-31-2014 07:08 AM in reply to: Steve_Stafford
Thats what I did, I did define my formulas well, and it stretches fine in the family. And I want it to "adjust to be only an acceptable size afterward." Its just not DOING that. Have you looked at the family I attached?
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michaelmead
Posts: 296
Registered: ‎03-02-2012
Message 7 of 26 (189 Views)

Re: Linear frustration

01-31-2014 07:12 AM in reply to: Alfredo_Medina
Its not important to me to have a lean family. My computer is hefty and my project is small. I tried the method you described in "3)" but I dont like the segmented look it gives. This project is heavy on aesthetics. Hence my current arrangement. If anything, I just want to know WHY my formula works in the family environment but not in the project environment.
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Alfredo_Medina
Posts: 2,865
Registered: ‎06-11-2009
Message 8 of 26 (181 Views)

Re: Linear frustration

01-31-2014 07:46 AM in reply to: michaelmead

The family you are making is a structural framing family, that is created in the project by two clicks, endpoint and startpoint. How can you predict how many holes are going to be in each instance? You can't put all the possible numbers in that extremely long formula that you wrote.

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michaelmead
Posts: 296
Registered: ‎03-02-2012
Message 9 of 26 (175 Views)

Re: Linear frustration

01-31-2014 08:15 AM in reply to: Alfredo_Medina
I think you answered your own question. All my possible options are in fact in that formula. You'll notice that I limited it to 10' which made it a total of 62 possible out comes if I remember correctly.
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Alfredo_Medina
Posts: 2,865
Registered: ‎06-11-2009
Message 10 of 26 (171 Views)

Re: Linear frustration

01-31-2014 08:53 AM in reply to: michaelmead

Isn't it better to control the length and number of items with an integer parameter instead of writing a formula with 62 embedded IF statements?

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