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Creating a 3D Printed Moon – Part 2

Back in 2013 I prepared a blog post on 3D printing a moon model using Maya and Mudbox.

A friend of mine named Alex used the same process described in that blog post to create a plastic 3D printed physical model of the moon with exaggerated surface relief for the museum he worked at. This 3D printed lunar model was created as a learning tool for a summer astronomy program in Hong Kong called the “Stargaze Camp for All“. This plastic moon model was used to help visually impaired youth get an understanding of the moon’s surface and to allow them to feel the impact craters and other lunar surface relief details with their hands.

Since this model was designed for use by the visually impaired it was important to add some markings to the mesh so they would be able to easily figure out the earth facing side of the moon and the “upward” orientation for the model. This was achieved with the addition of a dividing line on the model’s surface along with two raised printed letters that were added to the spherical mesh to mark the top and bottom parts of the moon.

During the moon model’s creation stage, Maya’s extrude tool was used to add thickness to the Mudbox generated lunar mesh geometry “shell”. Several alignment pegs were also added in Maya so the two parts would clip together for added strength. The polygon mesh was then exported from Maya as an OBJ format mesh. To make better use of the 3D printer’s capabilities, the physical model was designed so it would be fabricated in two halves so they could be positioned side by side on the printer’s wide aspect ratio shaped platen tray.

Having the lunar surface printed as a hollow two part model also saved resources as less plastic resin was used compared to  creating the model as a fully solid object.

The moon model was printed in a special high resolution 3D printer that works by curing an ABS plastic like liquid resin called EnvisionTec Perfactory LS600. The 3D printer machine has two main components that make it work: A high output UV light source that is provided by a DLP video projector like system that is located at the top of the 3D printer, and a liquid resin holding tank with a movable platen tray that is located at the bottom of the printer. As the UV light is projected onto the top layer of the liquid resin it slowly turns the material into a solid plastic.

In order for the 3D printer to create the physical plastic version of the lunar model, the polygon geometry of the moon was broken down into very thin slices that were then sent to the printer as a series of hundreds of greyscale images that were projected as a UV light pattern by the 3D printer onto the UV sensitive liquid resin. As each layer of the design was exposed using high intensity UV light, the plastic resin at the top of the tank cured and the model slowly took shape over many hours. Then the platen tray was lowered down into the tank by a fraction of a millimeter and the next layer of the design was printed in the liquid resin bath.

Once the completed lunar model was taken out of the 3D printer the temporary support structures that the printer added to the model needed to be cleaned up. Finally, the last stage of the model building task was for the two part model to be glued together with an ABS plastic safe adhesive glue.

Fabricating a 3D Printed Moon Model

Here is a quick photo tour of the process of creating the plastic moon model using a 3D printer.

The Mudbox sculpted lunar surface was loaded in Maya so the model could be prepared for printing by cutting it in half.

The Mudbox sculpted lunar surface was loaded in Maya so the model could be prepared for printing by cutting it in half.

The displaced surface of the moon model had thickness added in Maya which made the center hollow and saved on the amount of plastic used when the geometry was 3D printed.

The displaced surface of the moon model had thickness added in Maya which made the center hollow and saved on the amount of plastic used when the geometry was 3D printed.

The PolyTrans for Maya plugin was used to export the moon surface geometry to the STL file format so the data could be loaded into the Magics 3D printer software.

The PolyTrans for Maya plugin was used to export the moon surface geometry to the STL file format so the data could be loaded into the Magics 3D printer software.

The Magics EnvisionTec Ultra software comes with the 3D printer and is used to position the model on the 3D printer's platen tray and to add the required support structure material that allows the printer to make concave surfaces and hollow regions.

The Magics EnvisionTec Ultra software comes with the 3D printer and is used to position the model on the 3D printer’s platen tray and to add the required support structure material that allows the printer to make concave surfaces and hollow regions.

The Magics software outputs the sliced layers of the model as a series of images that are then sent to the UV Light based DLP video projection system in the 3D printer that cures the liquid resin plastic.

The Magics software outputs the sliced layers of the model as a series of images that are then sent to the UV Light based DLP video projection system in the 3D printer that cures the liquid resin plastic.

The 3D printer control panel allows you to load the model data into memory and program the printing settings to get the maximum quality possible.

The 3D printer control panel allows you to load the model data into memory and program the printing settings to get the maximum quality possible.

The liquid resin bath is topped up prior to the 3D printing process starting. The 3D printer also moves the platen tray so it is raised to the top of the liquid holding tank so the first layer slice of the model will be affixed to the tray when the UV light based printing phase starts.

The liquid resin bath is topped up prior to the 3D printing process starting. The 3D printer also moves the platen tray so it is raised to the top of the liquid holding tank so the first layer slice of the model will be affixed to the tray when the UV light based printing phase starts.

The 3D printer then starts the multi-hour process of bombarding the liquid plastic resin with high intensity UV light. This causes the liquid resin to turn into a solid plastic and gives rise to our 3D printed moon model.

The 3D printer then starts the multi-hour process of bombarding the liquid plastic resin with high intensity UV light. This causes the liquid resin to turn into a solid plastic and gives rise to our 3D printed moon model.

This is a view of the freshly printed moon model as it was raised out of the liquid resin holding tank for the first time. At this point the printing job has finished.

This is a view of the freshly printed moon model as it was raised out of the liquid resin holding tank for the first time. At this point the printing job has finished.

The moon surfaces were printed in two halves so the lunar surface relief would not have any support structure material touching the delicate crater impact surfaces. The hollow bottom part of the moon had a delicate support lattice like material bonded to it that was then cleaned up manually when the model was removed from the 3D printer.

The moon surfaces were printed in two halves so the lunar surface relief would not have any support structure material touching the delicate crater impact surfaces. The hollow bottom part of the moon had a delicate support lattice like material bonded to it that was then cleaned up manually when the model was removed from the 3D printer.

This is a moon surface after the support structure was cleaned up and removed.

This is a moon surface after the support structure was cleaned up and removed.

The two moon halves are visible here in their almost complete state.

The two moon halves are visible here in their almost complete state.

The moon surfaces are inspected one last time and then prepared to be glued together using an ABS compatible glue to merge the two halves back into a single moon model.

The moon surfaces are inspected one last time and then prepared to be glued together using an ABS compatible glue to merge the two halves back into a single moon model.

This is the finished moon model when viewed from the side.

This is the finished moon model when viewed from the side.

This is a view of the top of the moon. The letter T was added here so people could feel the lettering with their fingers and work out the orientation of the model.

This is a view of the top of the moon. The letter T was added here so people could feel the lettering with their fingers and work out the orientation of the model.

This is a picture of the moon model standing next to the bottle of 3D printer resin material that was used to create it.

This is a picture of the moon model standing next to the bottle of 3D printer resin material that was used to create it.

3D Printing the Chang’e 3 Lunar Landing Site

A few weeks later my friend Alex was tasked with 3D printing a model representation of the Chinese Chang’e 3 lunar landing site for an exhibit at the museum. He used a similar approach in Maya to create this model as was used for the previous spherical moon model. I think the final spray painted lunar surface from this project looks amazing!

A few weeks later a lunar surface model was created in Maya to show museum visitors where the Chinese Chang'e 3 lunar probe was going to land.

A few weeks later a lunar surface model was created in Maya to show museum visitors where the Chinese Chang’e 3 lunar probe was going to land.

The lunar impact crater mesh was given thickness in Maya and prepared for printing using the same process as the previous moon model.

The lunar impact crater mesh was given thickness in Maya and prepared for printing using the same process as the previous moon model.

This is a close up view of the lunar impact crater region that the Chang'e3 lunar lander flew over when it touched down on the moon.

This is a close up view of the lunar impact crater region that the Chang’e 3 lunar lander flew over when it touched down on the moon.

This a photo of the final 3D printed lunar surface model. The plastic model has been spray painted with a matte grey color to give it a more accurate lunar appearance.

This a photo of the final 3D printed lunar surface model. The plastic model has been spray painted with a matte grey color to give it a more accurate lunar appearance.