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Truss pickup modeling tips - for spansets

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Hi all,


Could anyone share any tips on tools & process to model you own truss pickups with spansets?  It's an interesting 3D modelling exercise that's currently beyond my skill set to do accurately.  It would be great to put a set of symbols together to show the various wrap options, and what can be achieved with the set lengths of spansets available in the UK.  





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While not difficult to simply model spansets or Gacflex, I tend to think you would have to physically wrap a specific unit around the specific truss and then measure the outcome. You could mathematically calculate the resulting length and probably be close enough, but not as accurate as physically wrapping a truss. 

You also would want to consider just how accurate and realistic you want your wraps to look. Do you really need curved surfaces and realistic looking straps?  You can do that, and even put the labels on them, but those become things that slow the program down. 

I created mine as pretty simple geometry and added a miniature “target” in 2D to line up with the rig point and a piece of text detailing the truss size, type of wrap and height of the hook above the lower chord so I know where to place a hoist. All that hides beneath a rig point symbol. That, of course, does not take into account any BraceWorks functionality. 

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  • Vectorworks, Inc Employee

What our content team have done is create a template file with 4 circles to represent the truss chords, linked using the dimension tool to make it easier to adjust them for different truss dimensions/configurations

and then they used several NURBS curve objects to make the path of the sling or steelflex, one for each chord that the sling has to wrap around and 1 for each straight section needed to link the wrapped sections and the final section going up to the shackle.

once the NURBS are correctly lined up they get combined into a single NURBS curve which is then used for an extrude along path to create the sling geometry.


The advantage of using NURBS curves is that they display their length in the OIP, allowing you to make sure the resulting sling or steelflex is of the correct length



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