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In this tutorial, we’ll see how to create an assembly that has sub assembly spans.
In addition to spans that consist of profile members and components, spans can be sub-assemblies. These are assemblies within assemblies, that act as spans, placed between the support components of the main assembly.
For a simple example of a sub-assembly span, bring in Stepped Barrier Fence and build a sloped section.
The one component is the pillar, between which all of the spans run. There are four spans, three of which are profile members: the bottom of the fence, and the bottom and top rails. These all have Allow Slope unchecked, which is why they always remain horizontal.
The remaining span, called Inner Posts, is a sub-assembly. For details on this sub-assembly, click the Edit Sub Assembly icon.
The blue title bar means that the window contains sub-assembly details.
This simple assembly has one object: the component called Inner Post, spaced at 6” max and placed at path start, end, and junctions. There are no setbacks defined here, though setbacks are needed to keep the spans between the sides of the pillars.
Click Build and draw out this assembly to see what it looks like. When the blue title bar is showing, all operations such as building or saving, apply to the sub assembly and not the main assembly.
Use the Back arrow at the top of the sub assembly window to go back to the main assembly.
This is where setbacks are defined, relative to the pillars: 1’ from the pillar center to its side, and another 5” to the origin of the first post.
You could reverse how the setbacks are defined: 0” setbacks for the span itself, and 1’-5” for the sub assembly properties. The results would be the same after updating.
Just like for other types of spans, you can allow slope for a sub-assembly. The posts themselves remain vertical because that’s how they are defined within the sub-assembly.
For a slightly more complex example, here is a fence based on Railing Assembly 6, with some changes to the materials.
Of the four spans, three are profile members - the three rails.
The gray objects are the sub-assemblies, which are placed between the components called Post.
This is a pretty simple sub-assembly, consisting of one component - the post - which is placed at 8” max with posts at start and end. These are the supports between which the spans run.
The spans are the rings, which are components.
Now let’s see how to add a sub-assembly span to an assembly. Here is another barrier fence assembly, with pillar components whose origins are at the bottom center. The three spans are profile members. We want to run sub-assembly spans between the pillars.
The sub-assembly has to be defined as an assembly on its own before it can be brought in as a sub-assembly.
Start the sub-assembly in place between one set of pillars. Here are the objects to include: a vertical post component called Bar and a decorative component called Spire.
Copy the Spire component, make it unique, open it for editing, and flip it along its red axis.
Create a new assembly and call it Wrought Iron. Add a component called Bar and pick it from the model. Its origin is at the front left corner, and spacing is 12” max.
Next add the first span which will be a component called Spire 1. Pick it from the model, and choose the first alternating pattern.
The second span will be Spire 2, with the other alternating pattern, and zero vertical offset. Scale to Fit is checked for both spire components.
Erase these objects and build out this assembly, so that we can fix the spacing details.
For Spire 1, the end setback is fine at 0, but the start setback must be ⅞” to meet the edge of the ¾” bar. The same setbacks are needed for Spire 2.
The other setbacks and offsets will be set for the sub-assembly as a whole.
Return to the main assembly by using Get Assembly Attributes. You don't have to save the wrought iron assembly since it’s already in the model, and you can refer to it later.
To add the sub-assembly as a span, add a new span and make it a sub-assembly. Name it Wrought Iron and pick it from the model.
Now you can remove the reference sub-assembly and update the entire fence.
In X-Ray view, we can see that the sub-assembly starts at the center of the pillar.
So we need to add a start setback. This will measure 1” from the pillar center to its side, plus another 3” for a gap. The end setback will be 15” plus the ⅞” for the width of the bar. Now the gap is 3” on both sides.
The Up / Down offset must be 6” higher than it is now. And to make the sub-assembly perfectly centered within the horizontal rails, we need to add a small Left / Right offset of 7/16”.
Test out the new fence along a slope, and all looks good.
If you wanted to make changes to the sub-assembly, such as narrowing the post spacing, you could edit the sub-assembly, find the Bar component and change its spacing, the return to the main assembly, and update.
While the sub-assembly properties are showing, click save. This will save the sub-assembly and not the main assembly.
Now with the wrought iron assembly saved, open another assembly into which you want to place the wrought iron as a sub-assembly.
Find the saved assembly and draw out a section.
Get the main assembly attributes back, add the sub-assembly span, pick from model, and update.
All you need to do now is adjust offsets and setbacks, and we’ve successfully reused this assembly within another assembly.