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3DMTP For 3D Printing of Architectural Models

By Paul Munford, November 8, 2012

Would you like to see a physical manifestation of your digital 3D architectural model? Would you like to hold it in your hand, and show it off to your clients and colleagues?

The 3D printing is a process involves laying down material, layer by layer, to form a 3D object. This type of printing can work very well when we require full size objects of small digital models. Three-D printing sounds good, but the printers are relatively small, and so printing scale models of large buildings has its problems.

Buildings overall are really BIG, so printing at 1:1 scale isn’t practical -- or even necessary. At the other end of the scale, when we take an architectural element, such as a truss, window mullion, or handrail, and then try to print it at 1:100 scale, the element becomes so thin that the printer simply cannot output it.

When we try to ‘thicken up’ the elements to print them without warping or falling apart, we could easily spend so much time long remodeling the job that we really aren’t saving any time by reusing data.

But the folks at 3DMTP believe that they have the answer, so let’s take a look at what they offer. Here is what they say:

3DMTP is dedicated to making 3D scaled models printable and available to every CAD user at a reasonable price. The innovation is based on cutting-edge algorithms which study the geometric structure of the model, then identify and automatically fix problems that would have prevented it from successfully printing.
Service with a Smile

The service consists of three parts:

I Got Algorithm

3DMTP claims its algorithm reduce the time otherwise needed to fix models manually. It does this by analyzing and fixing common problems, such as reverse surfaces and open geometry.

In addition, we are able to specify with the Studio software the MTP (model-to-print) ratio, which is the minimum thickness for any part. The exact minimum depends on the printer model we want to use, and the scale to which we wish to ‘shrink’ down our model.

The final output is an STL or VMRL file that is sent to a print bureau, or downloaded to our computers for our own purposes.

Here’s a summary of the service provided by 3DMTP’s algorithm:

File Formats

The 3DMTP service and studio accepts CAD and BIM files in SketchUp skp, AutoCAD dwg/dxf, Revit rvt, STL, VRML wrl, X3D, Collada dae, Rhino 3dm, 3DS, OBJ, AMF, FBX and PLY formats.

Models that require multiple files can be zipped together and then uploaded. Examples include VRML or OBJ files that require textures files, or assembly files with external references. You can also zip a single mode file to accelerate the uploading of large files.

3DMTP Studio
Figure 1: 3DMTP's Studio software

Figure 1: 3DMTP's Studio software.

3DMTP Studio gives us greater control over the process. (See figure 1.) We can pick our printing method and scale from within the software, remove features completely and split, or section the model.

In addition to geometry, 3DMTP can read data such as model hierarchies, layers, families, and floors. This data is used by the 3DMTP algorithm to analyze the model.

3DMTP Studio software allows us to set the MTP parameter globally or in a selective manner. This means we can pick an overall MTP, and then selectively pick MTPs for individual objects, such as windows and glazing. See figure 2.

Figure 2: Sample 3D printed output of architectural models



Figure 2: Sample 3D printed output of architectural models.

 

For additive manufacturing machines that can print using multiple materials – such as Objet’s Connex line of 3D printers – we can split model files. An example is printing the base of the building in one material, and using a second material for the glazing of other thin items.


3DMTP says:

The average file size that we see is around 200k facets. There are files that are larger – perhaps a more detailed Revit or SketchUp file. There are many programs that measure facets and our 3DMTP Studio software provides facet size feedback so you can estimate a file there before processing.
Beta Testing Program

As I wrote this article, the company was entering the final stage beta testing program and so doesn’t expect to launch the final product until Q2 2013. During this beta stage, the 3DMTP team is working with customers, helping them with the uploading process to ensure that the desired results are achieved.

Should you wish to participate in the beta program, contact the company through its Website at www.3DMTPUSA.com.

Interview With 3DMTP

To learn more about the 3D printing service, I interviewed Ilan Sidi and Phil Magenheim of 3DMTP.

Q: How does your service handle regular 3D print files such as STL and VRML?
A: STL and VRML are all treated the same. Uploading the original architectural file is, however, recommended, because information may be lost when exporting the original file formats to STL or similar format. In addition to geometry, our software reads other data, such as hierarchy, layers, families, and floors in Revit. Data can be used by algorithms and when using 3D MTP Studio.

Our printable output is either STL or VRML (wrl) for those wanting textures added.

Q: Can customers upload multiple models at once? Or is it one per zipped file?
A: Zip files are intended for formats with multiple files. Examples include VRML and OBJ with textures files, or assembly file with external references. You might upload a single design file inside a zip file to compress it and so accelerate large file uploads.

Q: What are your plans to offer support for any other neutral file formats in future?
A: We support many of those now, such as OBJ and STL are supported. We’ll consider others as the market demands.

Q: How do people get a hold of 3DMTP Studio?
A: We offer a trial of the 3DMTP Studio, so you can request it. We will soon be offering online training Webinars, and are now producing videos that will help customers quickly start using Studio software.

Q: Does the algorithm work equally as well in the interiors of buildings as it does on exteriors?
A: Yes. The software looks at objects to be printed, taking into consideration the printer, the scale selected, and the Model-To-Print parameter (MTP). 3DMTP adjusts all objects to be printable according to the parameters.

Q: How does the algorithm handle ‘thin’ objects, such as glazing?
A: The Studio software allows customers to set the Model-To-Print parameter (MTP) globally, or selectively. This lets customers pick an overall MTP, and selectively pick a MTP for individual objects such as windows or the glazing.

For additive manufacturing machines that print using multiple materials – such as Objet’s Connex line – customers can split a single model file into two. For example, the base of the building can be made from one material and the glazing or other thin items in a second material.

Q: What architectural object has been the most challenging for your algorithm?
A: There is no item that has been significantly challenging for the algorithms. Many models were successfully processed by the platform.

One challenge for solid modeling of architecture is the proportions of particular entities or objects with respect to the scale and in consideration the minimum thickness that a particular 3D printer can produce. Unfortunately one parameter does not fit all models all the time, especially the ones with a lot of details such as designed using BIM or 3D architectural modeling tools. The 3DMTP Studio software allows you to set the parameters such as Model-To-Print parameter (MTP) for optimal results. Sometimes optimal parameters should be carefully picked. Expert advice is available as part of our service. We have seen many models that work out just fine at one set MTP.

Q: A quote from your testimonials reads:

A real revolution in the production model is the integration and understanding that together we complete each other in the ability to produce a model within a few days that is 70% a finished product, thus allowing the model builder to work on a number of models at the same time.

Could you quantify what 70% means? Perhaps you could clarify what building elements the algorithm handles well, and what it doesn’t handle well -- the remaining 30%!
A: The referenced testimony was from the owner of an architectural models shop. His 70% reference is to the building or models created in CAD, BIM, SketchUp, etc. The 30% refers to other items that the model shop needs to produce, such as landscaping, platforms, and lighting. His point is that 3DMTP saves him significant time, preventing him from manually repairing or building the physical models.

Q: What material/process does your 3D print service use?
A: Service bureaus that subscribe to 3DMTP have the option of joining our print network. As a result of our marketing effort, there are many potential customers who contact us simply wanting a physical model without an interest in actually preparing the model file themselves. This can range from just the building itself or a fully decorated architectural model. The customers are referred to our service bureau subscribers that we feel will best meet the needs of that lead.

Subscriber’s equipment available will range widely. We have several that own just one type of printer, while others have a vast assortment that supports a wide range of materials.

Q: What is the minimum wall thickness that your service can print?
A: Minimum thickness is parameter of the process. Customers can define the minimum thickness that the target 3D printer should print, such as 1, 1.5 or 2mm.

The thickness depends on the capabilities of the 3D printer being used. Referring back to the last question, those requiring very find detail will be referred to a service bureau using the best equipment.

Q: What is the largest bed size/chamber cubed that your service can print?
A: Same answer as for the previous question: it depends on the equipment.

Q: Are your models available in color?
A: Yes, we produce color model files. We deliver a WRL file with a MAPS subdirectory containing the texture files.

Q: How are the models finished?
A: Many options exist. Again, we refer to printing service bureau that has the equipment and capabilities to meet the requirements.

Q: What makes 3DMTP unique?
A: 3DMTP is dedicated to making 3D scaled models printable and available to every CAD user at a reasonable price. Our innovation is based on cutting-edge algorithms that study the geometric structure of models, and then identify and automatically fix problems that might have prevented them from being printed successfully.

Q: What are the future plans for 3DMTP?
A: Based on feedback from our customers, we plan to update the interface to best meet their needs, and to create additional tools to produce 3D printable models. To support this product update we have launched a Beta program to generate models for analysis and consumer input. This will give us the data we need to give our consumers the best user experience possible.

We plan to expand our reach to other areas of the additive manufacturing markets in which we can help. We are committed to providing a state-of-the-art experience that simplifies and enables a seamless interface between CAD and 3D printing.

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About the Author

Paul Munford is a CAD manager and writes in his blog, The CAD Setter Out, which contains tips, tricks and tutorials for woodworkers using AutoCAD and Autodesk Inventor. More…

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