Revit family - area constraint

[Anonymous]

Hi

We are creating a parametric family for our window product.  We have managed to create maximum constraints for both height and width.  However combined with the maximum height and width we have a maximum area alllowance.  We are struggling to find a way to build this into our parametric family.  Does anyone have any advice on how this might be achieved?  Is it possible to display warning text boxes within Revit?

Any tips would be greatly appreciated

James

[Alfredo_Medina]

Yes, you need to establish a range of valid values. Check Wikihelp or Revitforum for the topics of formulas. In both places, you should find a part in which I contributed with a sample for ranges of values.

[DylanRead]

Hi Alfredo,

I'm working with james creating our revit product families.

At the moment we have some basic constraints/parameters for the product e.g. width and span.

for both of these I've created min and max values and as per the wikihelp 'formulas for everyday use' so at the moment the parameters with calc at the end are the dimensions driving thhe sketches, as per the attachment.

The issue that I'm having is coming up with a formula that allows both the width and span to be set at their min to max values, but stops users from being able to enter combinations which result in an area greater than the area max parameter.

I was thinking along the lines of adding an additional if statement, or some kind of formula that would back off the offending dimension in some kind of loop until the area value was in the permissable range but I'm a bit stumped as to how I'd do this.

Any ideas as to how this could work?

any advice/solution much appreciated!!

Dylan

[Alfredo_Medina]

Why not simply handle the window family with type parameters instead of instance parameters? That's how window families are, typically. If you give the user instance parameters, then you get into all this trouble of maximum and minimum values, etc. Before proceeding on that, why not simply give the user a set of types, already with dimensions that comply with the restrictions?

[DylanRead]

Hi again Alfredo,

I'm pretty new to revit so if there's something that seems quite obviously overlooked with my implementation it probably is!

As a bespoke rooflight manufacturer, the products that we offer can be produced to fit an upstand to the nearest mm in either direction, hence why I *think* I'm trying to implement the constraints in the manner that I am.

Once I've cracked how to create a stable bespoke fully parametric family per product, I will be creating a family per product type of standard sizes 900x1500, 1250,1000 etc. and adding each type with fixed width x span which I think is what you're getting at?

[Alfredo_Medina]

Well, usually, window families are handled by types. It simplifies two things: the usage of the family for the end user, and the making of the family for the content creator. If you provide pull handles (instance parameters), you are taking more risks of having a family that breaks, and the additional formulas will make the family more complex, and the size of the family file will increase as well. It is better to have a set of simple families for specific purposes than a super family that tries to solve everything. The simpler the better.

[DylanRead]

I see what you're saying, and perhaps it is the case that the family could be simplified. I was hoping that our fully parametric families would be a showcase of the level of detail that we as a company provide. I've looked at the level of detail in some of the sample roof lights and wanted to create something more than just a shrink wrap from inventor or a basic frame with window.

One of the biggest issues I was hoping to fix was that when an input dimension gets constrained (e.g. user enters 5000 for the width parameter, width calc formula restricts it to 4000) an error box would pop up, or at least the width dimension input text would snap back to the actual value, rather than sitting there at 5000. 

Could I upload or PM you a copy of a work in progress, perhaps you could give me an indication of whether the complexity of the model is likely to be too great for mainstream use (which is our aim with the launch of our bim family webpage) as we're only using the software to product these families rather than use them

[Alfredo_Medina]

Who is going to use your family? Basically architectural offices. Suppose they are very busy doing a project for a school or a hospital, etc. They want a family that gets the job done, can be placed correctly, simply, so that they can continue doing the other thousands of tasks to do in their project. In general, they are not interested in how much detail you put in a family. On the contrary, they want an object that depicts, in a simple way, the object, and can be scheduled if necessary.

If they really want a detail, most likely, they are not going to zoom in into your family, but simply make a callout, go to a drafting view, and create a detail, or ask you for a detail of your product. If you want to show how detailed your product can be, invest some time in having some really good 2d details ready for when the offices ask for them, or include a URL in the family for additional information. But do not complicate the family with unnecessary information.

What you said about a text popping out saying "you went beyond the maximum" is possible. But again, that takes more time, more skills, consumes more memory, and it's probably not expected, and not necessary if you simply provide types in the family wth the valid sizes, and some additional information in your website.