The Dubai Bridge Project

Making the most of a digital model is key.

Once you've got a 3D CAD file it makes sense to use it in as many ways as possible.
Rendering, animation, 3D Print. In this case the model was used for 4 total 3D printed models. 1 model was replicated 3 times while being combined with a laser cut base and the 4th was built at a much larger scale combined with excellent craftsmanship in the art of model making.

What started out as some messy STL files turned out to be a big winner for the client.
Models designed in Rhino

The files were partially fixed in Rhino using mesh tools and in Magics on our end. (see previous post for more details about Magics)

After the fixing we printed the models on the Objet machine. The models were used in conjunction with clear plexi as a base and the models were mounted. We did a series of tests before the full model was produced. Using FDM (Dimension) machine, High Speed Objet and High Quality Objet. The architects were new to the technology so they wanted to see the differences. The samples gave them the clarity they needed and they went with High Quality Objet in white. The model was going to be quite small and all curvature they wanted perfectly smooth so the resolution had to be very high. Oh yeah, the models were painted white.

In terms of size, the base is about 2 feet long. Looks bigger than it is.

Incredibly we were able to print the wire beams that connect to the bridgeway, but they were so thin that they would bend when you hold them. That wasn't going to work. So to work around this problem we helped them design tiny holes in the bridge arch and the roadway so that metal wire could be inserted as a post process. This also went through tests. It was really exciting to see their faces when the whole thing started to come together.

Well they brought the model to the Shiek in Dubai and wallah. He wanted it for himself and of course, he wanted another one. And not just more of the same but he also wanted one much bigger. So that is exactly what they did. We replicated that same model a total of 3 times.

For the larger model we used the same 3D file with some small adjustments. The brigde was cut into sections. This time they used the Dimension machine. Taking advantage of the strength and its light weight were advantagous for such a large model.

The model was built in sections and then sealed together by heating metal latches till they were very hot and placed them half on one piece and half on another. Each piece between the metal latches is roughly 12 inches long.

When you zoom in you can see better.

And finally as it gets put together from one of NY city's best model makers.

Notice that he is surrounding the model in a thin sheet of wood. This is for the surface finish. I asked him, "just use the wood and forget the protoype, all you need is the outside!" He responded. "We can't use regular wood because the shape is too complex, traditional methods won't work. Also, the balsa wood we're using isn't strong enough to suspend the bridge roadway. There is no other way to do this than to prototype it".

And the final pictures. They were able to build this model from the same 3D file. It was sliced into separate sections so each could fit inside the bed of the machine.

This model is for Turner Construction. They are using it to view the constructability of the curtain wall. It was used in a demonstration to other Turner Technology people and they were very impressed. It appears that there is value for construction companies to use 3D Printing as well. We learned a lot from Turner in this area and appreciate their allowance to let us use photos of their model.

3D Printing Guide for Architects

Justin Levitz, Manager of 3D Technology for NRI

Overview
It is well known that 3D Printers were not created for architects. In fact most manufacturers of 3D Printers probably didn’t even see the possibility for architects to use their machines. Instead, these layer on top of layer printers, known as 3D Printers were created for aerospace, automotive and other engineering designers that require physical output or ‘parts’ to test or demonstrate some or all of their design. As architects tried the technology, it was quickly observed that their files were highly complex, far beyond the engineers and simultaneously contained many errors that prevented the machines from interpreting the files properly.

Fast forward 20 years and it is clear that many firms have integrated 3D CAD applications into the office and the design process. The architecture movement towards 3D Printing is nearing a tipping point. Yet, there are factors that will limit the integration of the technology due to pre-existing design techniques for visualization and the fact that many applications allows for surface modeling or line drawing, instead of just modeling solids that have a volume. As always, it will be proper training, the right 3D Printers and an organization that has the people and the experience to support architects needs that will allow them to maximize the benefits of this emerging technology.

Common Terms

STL file - .stl, Standard Triangulation Language. All prototyping machines can receive STL files to print. When you export or save a file as an STL, all of the surfaces and curves of your design are replaced and converted to a mesh. The mesh contains a series of triangles that represent the exact geometry of your design in its original state. Why is this important? The importance of knowing that this has occurred is that the resolution of the STL file will play a role in the quality of the model being built. The faces of the triangles may show up where their should be a smooth line. If this were to occur you would need to export a higher resolution STL file and thus make the triangles very small and unnoticeable or beyond the resolution of the machine. Questions? Post to 3D Printing for Architects on LinkedIn

Watertight – STL files need to be watertight in order to be produced on a 3D Printing device. Watertight can best be explained as a solid with volume that has no holes. Amazingly, even though you’ve created solids in your design, there still may be holes in the model that went unnoticed.

STL errors – Once you export your design file to the STL file format often times ‘errors’ are identified. The errors are not in the exporting but are actually in the objects of the file. Just like a software compiler will check a program for coding errors before processing so too, a 3D Printer or an STL viewer can check the STL file before it begins to print. If it were that the machine encountered a problem with the file while it was building the model, the machine would crash and stop building completely because the cross-section of the file was corrupted. Resulting in a failed print. Using a good STL viewer is key. (http://www.minimagics.com/)

Cross-sections – Once the STL file is created the 3D Printer will ‘slice’ the file into a series of cross-sections. Similar to how a laser cutter creates the cross sections then you assemble, here we start with the entire object and slice into cross sections. The cross sections will be exactly the layer thickness of the machines capabilities. All 3D Printers work by producing a series of cross-sections, one on top of another, layer upon layer, cross-section on top of cross-section until the model is complete.

Layer thickness – each 3D Printing technology has physical specifications and thus limitations. One of the most important specifications is the thickness at which the machine builds a layer (aka the cross-section). If you have a detail as thin as .001” in resolution, but are using a machine that produces using .01", you can say goodbye to that detail because the machine will skip it entirely. Working within the parameters of the machine specifications is critical to proper output of your 3D Design.

Model Material – Each 3D Printing technology uses different materials to produce the cross-section of information. Materials range from plastic to liquid resin to powder to wax. Support Material – Each 3D Printing technology will use support materials to support areas during the cross-sectional building of the model that need support. In short, any geometry that does not have model material beneath it will generate support material. All 3D Printing technology uses support material. The closest is ZCorp that uses the model material as support material. There are costs associated with using the support material similar to the model material. Common

Applications

Revit – downloading the STL Exporter makes for easy exporting of your Revit model to STL. Revit is a solid modeler so all the solids should be watertight and contain few errors. There will be some difficulty in that objects need to be flush. It appears easy to miss these areas before exporting so often many exports will be done before achieving something successfully. We recommend building 2 models. One will be for construction and the other for 3D Printing.

Rhino – Often surfaces or single lines are created to create the desired visualization effect, without having to using solids. This speeds the design process for visualization but is definitely missing the point when it comes to STL files. Yet, my experience is that there are quick tricks to fixing Rhino files. More to come in a future post.

3DS Max – Excellent at creating STL files. Problem is most files designed in Max were used for visualization. Turning a visualization file into a prototyping file is not something to make a career out of. Though possible to do, the ideal strategy is to design with prototyping in mind.

Sketch Up –No direct export to STL. Though I found one at (http://www.ohyeahcad.com/). I believe that SketchUp used to export directly from the Pro version and it was removed. I think there were too many issues in generating watertight solids from the program. However, we recommend exporting to dwg or 3ds and import into 3DS Max or Rhino and export the STL file from there.

Magics – a powerful STL application recently released version 13.0 that can fix and manipulate STL files precisely as desired. While using the native application can be effective to fix STL or model issues, using Magics is quite efficient. Many tasks that need to be fixed in the native application can be done in Magics a lot faster. Designed primarily for Engineers using the Stereolithography machines (SLA), they have begun to integrate nifty ideas to help fix architectural files such as ‘shrinkwrapping’. Magics can fix holes and bad edges, Boolean union two solids, invert triangle normals, create solids into shell structures and many other features. While the application is excellent there is a bit of a learning curve to become efficient. Common

Sites with information

http://www.deskeng.com/

http://www.sme.org/

http://www.tctmagazine.com/