Revit is not propagating calculated values from nested family into parent family

[Anonymous]

Hi All,

I've met a problem with propagating values of calculated parameters from a nested family to parent family. Let me explain it by using an example:

I've created a generic model family (let's call it Family 1) and created four parameters inside of it:

A,B,C (length instance parameters)

D (volume instance parameter)

I have assigned a formula to D parameter which says: D=A*B*C and its calculating the volume basing on a A,B,C parameters.

When I load this family into a project it works fine. I can manipulate A,B and C parameters and value of D is calculated automatically.

Then I've made second generic model family (lets call it Family2) and created another A,B and C parameters. I've made Family 1 a shared family and loaded it into Family2. Then I've linked A,B,C parameters from Family1 to Family2, so the nested family should get A,B,C parameters from Family2.

When I load this family into a project, I can manipulate A,B,C parameters and they are being propagated into nested Family1, but Family1 does not calculate value D anymore.

Have anyone meet similar problem? In my opinion, there is nothing complicated from a logical point of view but it doesn't work for me.

I would appreciate any help.

Regards,

Jakub

[Ilic.Andrej]

Hello,

You need to decide whether the parent drives the child or the child is shared.

If the child is shared, imagine it as an independent component which can be loaded into other families. Its dimensions are not driven by the nests. You should only constrain the position of the shared component. So lets say you nested a faucet into two different sink components. If you change the faucet type properties in the project environment, that will update both sinks. The type properties of the sink do not affect faucet dimensions, so forget about it 🙂

If the parent drives the child (its dimensions that is), the nested family should not be shared and all its parameters should be instance parameters. Lets say the parameters of the parent are A,B,C and they constrain the parameters of the child which are also called A,B,C. The volume D will be calculated with the use of the parameters of the parent, not the child.

[Anonymous]

Hello dr Grozozo,

Tank you for your reply. So basically what you say is I have two options:

1. I will have my child family as shared family and it's dimensions(parameters) are type parameters

or

2. I will have my child family as dependent from parent family and it's dimensions are instance parameters which are linked to parent.

You are not giving me much of choice. First option don't work for me, because I want all dimensions of the child to be dependent from parent. Second option don't work for me, because if nested family is not shared, I won't be able to choose it / click on it from the level of project. And you say I should not mix these two together.

So I need to disagree 🙂

What I did, I created a nested shared child family and linked its instance parameters to parent parameters.

And what works well for me is that you can change type parameters of parent and the child will also change it's dimensions. And you can click and select child family from a Project level (so I can schedule it for example).

What doesn't work well for me it Revit is not updating calculated formula values inside child family. When I create a single instance of a child family inside Project, Revit calculates it very well. But when it's inside parent family, the formula is not being recalculated and refreshed.

Do Revit have some memory limits for calculating formulas inside nested families? I believe it could be a software problem.

Regards, Jakub

[Ilic.Andrej]

I suppose it has...

[Anonymous · Accepted solution]

Hi guys,

The example I've described was much more simpler, than the family I was using in my project. What I found out, is Revit in deed has a memory/computational limit for formulas in families. When I've started to clean up family by simply deleting unnecessary parameters, all the formulas started to calculate within nested family properly.

That's why I think the topic should be closed and this post marked as a solution.

On the other hand, I will try to investigate the problem with memory.

Regards, Jakub

[Ilic.Andrej]

Interesting, good job