Partial Rebar Shapes

[scottjames121]

Is there a way to use only select dimensions of a bar shape without Revit changing the shape code to "Rebar Shape 1"?

Example attached. I want to use only B, C, H, & K parameters of Shape 3 to create a simple angled bar.  However, when i set all other legs to 0", it reassigns the bar to Rebar Shape 1.

[ovidiu_paunescu]

How are you changing the values to 0? Are you sketching the shape and on finish it creates a rebar shape 1?

If you just edit one of the values in the bar properties to 0, you will get an error and the shape cannot be created.

[scottjames121]

Hello, and thanks for the quick reply.

It happens both when I sketch the rebar, or add shape driven rebar from the scroll-down list.  In the attached pictures, I sketched the bar, which Revit sets to "Rebar Shape 12".  I manually change it to the US rebar shape "03" and it gives me the entire bar.  When i start removing hooks and legs, Revit converts the bar to "Rebar Shape 13", instead of keeping it as shape "03", just without some legs/hooks.  The same happens if i insert a shape 03 bar into an element using the parallel/perpendicular to plane method, and start setting legs to 0 inches.

As long as the bar has continuous segments, i get no errors reporting that the bar can not be created.

[ovidiu_paunescu]

Hi @scottjames121 

Rebar shapes in Revit are defined by the rebar shape family which specifies geometrical relationships between the segments that make up the bar.

Removing or adding segments produces new shapes, since the new geometry doesn't match the geometry defined in the shape family.

Bars adjust when dragging handles or when the host adjusts because, besides the segments, shapes also have dimensional constraints defined in the family.

You will notice that dimensions with assigned parameters for each segment or angular dimensions for angles between segments.

If a the angle doesn't have a dimension with a parameter assigned, that angle is considered of a fixed value, so sketching the same shape with a slightly different angle will create a new shape

If we add an angle value between the segments, any two segment sketch with an angle between 90 and 180 (strictly greater and less than) will match that shape.

In the same example, if Rebar Shape 1 is defined like this (in the shape family)

Sketching similar bars will match that shape

Please note that you can edit the shape families, rename and customize the segment length parameters however you need.

This is a quite large topic, so you can find more information about shapes here and about editing shapes here

Shapes are also influenced by hooks and coupler end treatments.

If these are included in the rebar shape definition, the shape changes when adding or removing hooks or end treatments.

Let me know if you have any questions

[scottjames121]

Thanks for the explanation of how Revit treats shapes.  Maybe this is something I should move to the Revit Ideas forum, though.  The situation I'm trying to describe is that rebar fabricators have a standard set of rebar shapes to choose from.  As rebar detailers, we try to keep all our bent bars defined within the bounds of these standard shape definitions so that we do not have to create custom shapes.  One of the tricks we use is to have the bar defined as a standard shape, but with null lengths on select legs.  This way, fabricators do not have to add a bunch of custom shapes to their cnc bending machine library.  The attached example is from a 2D program we currently use.

Thank you