Simple family flexing erratically

[gsucci]

Hello,

if you have a few minutes to spare, please see my problem here:

You can actually stop viewing the video half way, since the second half is just more of the same issue / problem but on a second family.

Thank you

Gio

[PijPiwo]

I think your radius parameter could be messing things up. Do you even need it? I tried without it and it seems to be working fine.

[Anonymous]

Did you flex your family's width parameter?  I believe Gio is absolutely correct.  Something is wrong in Denmark!  I just made a simple sweep and didn't use the radius constraint and have similar problems with it acting erratically.

[video]

[PijPiwo]

I do have ends locked, radius is not locked and radius parameter is removed. I’ve flexed this family 30 or more times and it’s working as expected. The file is enclosed (2018).

[PijPiwo · Accepted solution]

The key here in to not constraint the radius.

[gsucci]

Spike,

I cannot see your video, which is tiny in your post.

However, PijPiwo suggestion seems valid.

I have removed the radius constraint and parameter altogether. The arc will not flex properly without it, unless you also lock its center to the vertical center axis. You need to turn on the center mark of the arc first.

Locking the arc in this way (also locking the ends to the left/right axis) seems to make the flexing much more stable.

The Rise parameter alone is able to flex the arc.

Thank you

Regards

[Anonymous]

Just be prepared because I believe your problem is still there.  I thought I had it fixed as well but even without the radius constraint there was still an unpredictable problem with it when I flexed it enough.  Mostly happened after I flexed the width (W) and then the Rise factor again.  If it worked a I am glad for you but as I mentioned I have had this problem on other families I have worked on.

Not sure why the link to the video (on Vimeo) doesn't allow you to control the screen size like YouTube.

 Revit 2017 - Erratic behavior of constrained arc

[gsucci]

Thank you Spike,

I watched your video and, from a slightly different angle, you hit a very similar problem, that is, the unpredictability of some of Revit's behavior.

Once you had your constraints done, there was no reason whatsoever why Revit could not flex the family going from certain values to others, as you are clearly showing.

Maybe there are better ways to constrain the arc, which makes it more stable: for example, turn on the visibility of the center of the arc and lock that to the center axis, instead of using dimensions locket at zero.

Thank you again,

regards

[PijPiwo]

@gsucci, can you upload your family?

[Anonymous]

I did not save the file because I was only trying to help Gio.  I thought a similar problem I had with erratic angle constraints (for the past 8 releases) would be able to provide a similar solution for Gio.  I decided it probably wouldn't take long to recreate the erratic curve behavior family and I figured the problem would be there even if I constrained it as you and Gio recommended with the center tic.  Alas, it only took a couple of minutes for the problem to reappear.  

Revit 2017 - Continued Erratic curve behavior

The erratic angle behavior I was talking about is when a nested family is rotated at certain angles it cause the constraints to be dropped.  This can be solved by If then formulas not allowing those exact angles to be used.  It has frustrated me for years and I thought maybe someone would have an answer on why it is happening.

Revit 2017 - Erratic angle behavior

I have attached both families in 2017

[PijPiwo]

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@Anonymous wrote:

I figured the problem would be there even if I constrained it as you and Gio recommended with the center tic.

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@Anonymous, I have never recommended constraining the center point, imho it shouldn’t be.

I noticed in your family that your right ref line end is not locked to the horizontal ref plane. I’ve fixed this in the attached file and I’ve removed the center constraint.

Sometimes, revit has a hard time to go from .1 to the higher numbers like 1 or 2. As long the rise parameter is not less than .2, it seems to be working fine every time.

Revit never liked shallow angles or sharp, pointy corners, I think making a rise .1 is one of those things revit is not happy about.

In regard to your angle family, you need to put your object on the ref line's ref plane - see this.

[Anonymous]

Agreed.  Thanks for your time.  

Have a great week