Why does this window work?

[Joef]

I have a window which flexes perfectly and when I look at it to modify it I can't figure out why it works. My question is: What is controlling the muntins? There seems to be no logical connection between the reference planes and the muntins, but they flex perfectly. Whenever I build something like this from scratch it ends up being a complicated mess of dimensions and reference lines. How this particular window avoids all this complexity is a mystery to me.

Joe

[Elmo]

Seems as though the creator did most of the work when he was sketching the Extrusion for the mullions. When you edit it you can see where he has parameters and the like.

[Wes Macaulay]

You can add ref planes inside a sketch -- and they won't be visible when the sketch is finished. As long as no other objects need to reference these same ref planes, then what the creator of this window did makes good sense.

[Joef]

I see the reference planes inside the sketch but I cannot see anything constraining the muntins to the reference planes. I am seriously exposing my ignorance here but I just don't get it.

Joe

[Wes Macaulay]

Ha - Revit magic. I don't do this, but Revit allows objects near ref planes to move automatically with the ref plane, and this works fairly reliably when the ref plane is in a sketch. So the sketch lines move along with the ref planes inside the sketch.

I almost always put dims on anyway since I don't trust Revit to ALWAYS do this.

[Elmo]

Ha - Revit magic. I don't do this.....

I almost always put dims on anyway since I don't trust Revit to ALWAYS do this.

I also put dims since then I don't have to second guess things. I have noticed that things are more likey to do this Revit Magic when you are using Extrusions and Sweeps. It doesn't do so well with Revolves and Blends.

[Joef]

Is there a scrap of documentation anywhere regarding this "feature"? I had no idea that you didn't have to lock sketches to the reference planes. Goes against everthin' I ever learnt. Like how near is "near" anyway.

Joe

[todd.69291]

Try turning on the "temporary dims". This will show many more dimensions.

[Joef]

Interesting. Here is the relevant info from the manual:

Revit Building creates automatic sketch dimensions in the Family Editor to define where every sketch line is, relative
to reference planes or other sketch lines. The automatic sketch dimensions implicitly constrain sketch lines, until you
explicitly dimension those sketch lines. As you add dimensions, you are telling Revit Building your design intent.

This is going to save me tons of time. I had no idea that constraints were automatic until you actually added a dimension. I guess all of you folks knew this but weren't telling.

Joe

[Steven Campbell]

Careful... Revit does try to constrain your sketch automatically but to what is the question. It tries to guess your intent, some time it works as expected but in complicated families with many layers of information it may not. Build the family up systematically and test (flex) often.

Constraining the sketch to reference planes is the most reliable method of building families.

Steven Campbell
Autodesk Revit