Other objects moving after Reference Planes and Dimensions are Added and Flexed

[davidwilliamedwards]

I wish I knew more about why this happens. I'm taking a simple table Family and adding Reference Planes and Dimensions in order to create a set of tables with different dimensions using Types. However as soon as the dimensions of the Table are changed the objects making up the Legs also move. I've Copied them to other placed in the file. I've Copy/Pasted them from another Family. Even put them in Groups. This is maddening. 

Original table Family

After adding Reference Planes and Dimension.

After Flexing - noticed the parts circled has moved - WHY???

[ToanDN]

Why don't you create two more reference planes to constrain the legs independently from the Length?

[davidwilliamedwards]

I'm actually much more interested in WHY this happens in order to not let it happen in the place. Fixing this particular Family is another issue.

[ToanDN]

Per my experience it is the normal behavior when you draw the elements AFTER the reference planes placement.  To test it?  Cut the two reference planes and paste them in place.  Moving them no longer affect the location of the two legs.

[davidwilliamedwards]

I created the References Planes after the model was finished.

[chrisplyler]

First let's deal with the top of the table. Your picture shows that when you flexed the table, the top did not flex symmetrically on the front edge and the back edge. The back edge did not stay on the reference line as desired.

Assuming the table top is an extrusion, it's sides are not aligned/locked to those new reference lines all the way around. You may be able to fix that directly, or you may first have to edit the extrusion and get rid of any conflicting dimensions or constraints that are in there (any dimensions created during the extrusion editing process will not be visible after the extrusion edit is compete).

If you can get that table top working correctly, you should have learned enough to diagnose the legs also.

[ToanDN]

Can you share the file?

[Sahay_R]

I would suggest modeling the tabletop in one family, the legs in another, and nesting them with associated parameters in a third. So much better control.

Or else, as @ToanDN says - share the family!

[davidwilliamedwards]

Good catch - I've been replacing the RPs so often, I forgot to lock them that time. After the 8th attempt, you get a little squirrelly. 

[loboarch]

---

@davidwilliamedwards wrote:

I'm actually much more interested in WHY this happens in order to not let it happen in the place. Fixing this particular Family is another issue.

---

Sometimes when things seem to be moving all by themselves not due to any constraints, it might be be cause of Automatic Sketch Dimensions. These are created in the background by Revit in an attempt to interpret "design intent". Most of the time they do things as expected and you never need to know about them. Sometimes a goofy thing will happen or they will control stuff in a way you don't want and you need to untangle.

I am not sure if this is what has happened in this case. You can turn them on in the Visibility and Graphics override dialog. It may uncover "WHY" the table is behaving the way it is. Not for sure, but it is one place you can look.

 

[ToanDN]

@loboarch

I think you nailed it.  And the automatic sketch dimensions don't even need to be locked to maintain the constraints.

[ToanDN]

This also confirms my statement earlier that if you draw the geometry before the reference planes, they are independent from those planes, since the auto sketch dims are not tied to those planes.

So I have a little doubt when OP said he drew the reference plane later in the game and still got the same effect.

[davidwilliamedwards]

Great call! I'll work with that ON and see what happens. This underlying "We're just trying help" can get in the way. I'd love to see an "expert" which is basically "Do only what I tell you to do". Sigh... I've been at this for way too many years.

[davidwilliamedwards]

Still does it... I see the Temp Dims, but how do you nullify they're effect? The next step is to use Groups of SubFamilies. I hate workarounds - "When there are too many exceptions to the rule, the rule must be changed."

Here is the RFA - have fun!

[davidwilliamedwards]

Trying to move sections as Groups - waste of time. The Mirrored versions are not the same as the original. Placing RPs into the Groups produces weird results with applying dimensions. 

Come on Reviteers - this is supposed to be basic stuff! No help after all this time... 

[Sahay_R]

Ok - you don't want the legs to move? They DON'T move in the attached family!

[davidwilliamedwards]

Requiring the use of embedded Family just to keep objects from moving when a single object is Flexed is simply WRONG! These internal constraints should never be created or at least made visual and deleted.

"Established workarounds equal lazy developers". 

[ToanDN]

Edit: Oh snap, I responded via an email notification as I thought it was a brand new topic.  Turns out it is old as dirt.

They may be constrained by automatic sketch dimensions.  turn them on and see what you can do.

[davidwilliamedwards]

You can turn then on in View > Visibility/Graphics - nothing appears.

(I've been a CAD Manager for 37 years - WHY IS THIS SO HARD? - I think I know the answer and it's just sad...)

[ToanDN]

Really?