Friday, 25 October 2013

BIM - 3D Printing - Hurdles to overcome

BIM has the one key ingredient needed for 3D printing and that is, 3D.  However, to get to a useful 3D print there are three main hurdles to overcome. 

1. Scaling

Because BIM is not a free-for-all modeler, objects that may be too thin to print at model scale may not easily be edited.  This usually leads to some re-modelling work outside of the BIM software to get to a 3D print ready state.

The image below shows the same data printed at 4 different scales.  Each one needed some editing to work at its particular scale. 

Model House printed at 1:100, 1:200, 1:500 and 1:1000 scales
Despite several attempts by software geniuses, it is still not possible to get a good scaled model from an automated process.  At Lee 3D we manually edit the file spending a good deal of effort to keep the detail clear and the design intent unaltered.  On a large dataset this can be time consuming.

2. Excess Data

A BIM model can become large and unwieldy when exported to a 3D printable format.  3D print data loses all of the object oriented efficiency of a BIM or CAD file.  For this reason the hinges on each of the doors and the text inscribed on each of the hinges can make a file very large indeed.

Where it is possible to export key geometry a good deal of time and megabytes can be saved.

3. Unresolved Geometry

Revit has an aversion to unresoved meeting points where structural parts should join.  Where details have not been fully designed, Revit carefully leaves all parts poised in readiness.  The consequence of this is that many structures contain large numbers of floating joists, beams and columns.  The hurdle is a double one as not only do all parts need to be extended a few mm, but it is very important that none are missed to avoid the model falling to pieces.

The image below illustrates the kind of thing that frequently occurs in Revit.  The beams would not quite reach the columns as this has junction has not been resolved.

In conclusion while BIM is great for 3D printing, there can be some hurdles to overcome in getting a good result.  Excess and unresolved data would seem to be the easiest hurdles to overcome.  How scaling can be addressed so that data can be reliably printed is still unclear.

For more information on 3D printing for AEC visit

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