Issue with Constraining two Parallel lines

[mhillis]

Hello all,

I am trying to build a shape for a family.  Here's the deal..

At the top of this shape, you will see two lines that are running parallel to the Ref Level plane (XY plane).  Off of these two lines, you'll see two lines that are angled going downwards.

What I'm looking for is the angled lines to run parallel to each other at a set distance apart, logically, the two lines above should be able to stretch accordingly to ensure that this happens.  There are automatic dimensions in place that kind-of/sort-of does this.  The problem is when I go and drop a dimension that controls the thickness of the parallel lines, the automatic dimension for the lines on top disappear.  This causes issues and prevents me from doing what I want to do.

I've attached screenshots and the family file, can anyone shed some light on why this is happening?

Thanks.

[L.Maas]

This is normal behavior. Revit normally create some standard constraints. As soon as you place a constraint the temporarily constraints from Revit will disappear. You basically overrule those dimensions/constraints.

The standard workflow of creating a workflow is:

-Create the 'frame' made of reference planes and reference lines.

-Add constraints and parameters to the frame

-Flex the frame to check if it behaves as expected.

-In case of issue add/modify the constraints

-Add model components and constrain them to the reference planes/lines.

-Flex the model again to see if it works.

-Load family in a project and see if it works there as expected.

Normally you try to avoid to constrain/dimensions elements to each other. You try to constrain/dimension elements to reference planes/lines

In your case I would add more reference planes/lines and constrain them before adding the extrusion(s)

[mhillis]

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@EnlInt wrote:

This is normal behavior. Revit normally create some standard constraints. As soon as you place a constraint the temporarily constraints from Revit will disappear. You basically overrule those dimensions/constraints.

The standard workflow of creating a workflow is:

-Create the 'frame' made of reference planes and reference lines.

-Add constraints and parameters to the frame

-Flex the frame to check if it behaves as expected.

-In case of issue add/modify the constraints

-Add model components and constrain them to the reference planes/lines.

-Flex the model again to see if it works.

-Load family in a project and see if it works there as expected.

Normally you try to avoid to constrain/dimensions elements to each other. You try to constrain/dimension elements to reference planes/lines

In your case I would add more reference planes/lines and constrain them before adding the extrusion(s)

---

Enlint,

Thank you for the reply, but there is still something that does not make sense to me.

As you'll notice with the Automatic Dimensions that Revit puts down, it has two for each of the parallel lines that I mentioned at the top.  It has 1 automatic dimension for the thickness of the angled parallel lines (like I want) and then one that controls the half length of the lines at the top.  When I drop a dimension down for the thickness of the two angled lines, would it not make sense for Revit to simply leave the other Automatic Dimension in place?

I don't understand why Revit has to remove both dimensions when I put one down.  When I could actually use one.

[L.Maas]

I do not have an answer for that. I do not know what internal rules Revit uses to (not) place certain automatic sketch dimensions.

That said, I do not rely on them and seldom use them. Most of the time I have the automatic sketch dimensions hidden.

Relying on automatic constraints/dimensions will risk of your family not behaving as expected.

I just make sure that I 'completely' constrain my family. Making sure that it behaves as I want/need.