Spans are an incredibly powerful feature and can be used to create highly detailed complex assemblies. There are three kinds of span parts: Profile Member spans, Component spans, and Sub-Assembly spans.
The span types have some common attributes but they also have some attributes that only apply to a specific type of span.
All spans are anchored by a 'Support' component part. The span parts will connect between two adjacent component parts.
Profile Member Spans
For this type, Profile Members will be created at each span location that connect between the adjacent support components.
A sub-assembly is a nested assembly that will be created at each span location. Sub-assemblies can also be comprised of their own component, profile member, and span parts.
Common Span Attributes: Support
Each span part must have a valid support component part or it will not be created. To create component parts, select the 'Component' tab inside the Assembly Dialog. Then, choose the span support from the drop-down list.
Common Span Attributes: Pattern
By default, spans will be created between all support components. However, it is possible to select other layout patterns.
Common Span Attributes: Cross Junctions
Junctions are discontinuities in the layout of the support component. Junction locations are specified using the Junction Angle setting of the support component.
The support component must have a junction setback greater than zero for this setting to have an effect. Otherwise, the support will be located directly on top of the junction.
Common Span Attributes: Setbacks and Offsets
Start Setback: Distance from the axes of the start support to the start of the span (measured along the assembly path)
End Setback: Distance from the axes of the end support to the end of the span (measured along the assembly path)
Left / Right Offset: Distance from the axes of the support to the span (measured along the assembly local horizontal direction)
Up / Down Offset: Distance from the axes of the support to the span (measured along the support's blue axis)
Common Span Attributes: Glue to Support
Glue to Support: If enabled, the Left / Right offset will be along the support's green axis and the setbacks will be along the support's red axis.
If you want the span to 'stick' to the same point on the support regardless of the rotation of the support, then enable this setting.
This attribute can be used for both Profile Member spans and Sub-Assembly spans. If disabled, the span will be forced to be horizontal.
This attribute can be used for both Profile Member spans and Sub-Assembly spans. If enabled, the span will follow the curve (if any) of the assembly path. If disabled, the span will be created along a straight line between the supports.
This attribute is only available for Profile Member spans. If enabled, each Profile Member span that is created will attempt to trim itself against the support components.
Note that only planar trims are supported for this feature.
If the Profile Member does not intersect the support, no trim will be applied and it will be as though the Profile Member was created with no trim or setback.
When auto-trim is enabled, the start and end setback settings are hidden since they are not used in this situation.
Sag can be applied to a Profile Member span or a Sub-Assembly span by entering a non-zero sag amount.
Sag Divisions control the number of segments that the span will be divided into before the sag is applied.
Sag Amount is the maximum distance for the sag to be applied at the middle of the span. Negative values can be used to create an arch effect.
Scale to Fit
This attribute can only be applied to Component spans. If enabled, each span will be scaled so that it fits exactly between the supports (taking into account the start and end setback settings).
Shear to Fit
This attribute can only be applied to Component spans. If enabled, a shearing transformation will be applied if necessary so that the component span fits against the support.
This attribute is important if the assembly is built along a sloping path.
When editing a sub-assembly span, the top of the Assembly Dialog window will turn blue and a new 'back' button will be visible so that you can navigate back to the parent assembly.
1. Click the 'back' button to go back to the parent assembly span.
2. It is possible to use the assembly browser to load a sub-assembly from a saved assembly SKP file.