College of Arts & Letters

AL Student Lab Documentation

LABS | HOURS | SIGNUP | INFORMATION

3D model builds

Arts and Letters Printing Services provides color 3D model builds using a powder bind method for arts and design students. This pages will document best practices for creating model files suitable for print.
If you have questions about the build process or models email al3dprints@csus.edu

Make Hollow Shells

In order for the software to determine the inside our outside of the shapes it looks at the models “Normals” which are perpendicular lines to the faces that point to the outside (usually used for lighting mathematics). If your object is a shell with all the sides closed off all of the normals point to the outside. If you happen to have a face on the inside of the shell there will be a normal pointing to the inside of the shell and the software will see that as an error or in worst case will cut your object in half when it is printing. Make sure that all your shells are hollow when you build your parts. Use X-Ray mode to inspect your parts for extra faces.

Making a water tight model

3D models are made up of points in space, lines and faces between those points. They can generate models that cannot exist in reality. You can design a model with very thin edges or just single faces but when it is built the powder cannot structurally handle the weight and will break apart. Also the printing software needs to calculate what is inside the model and what is outside. If a face is missing or the geometry is twisted the outside will leak to the inside and it cannot be built.
The best method of ensuring water tight models is to keep the geometry simple, and let the components of the model be whole objects. The parts can cross and merge for the sake of the printing software. If you have the components try to find the vertices where they cross many times the geometry is too complex to make a water tight skin around them.
The Letters are grouped and slightly embedded into the wall so no gaps and leaks will happen. The geometry of the wall is still simple. The letters are not grouped and are part of the wall geometry. This operation confused the modeling program and the cavities in the A and Ampersand leak into the interior of the wall. This will not build in the 3D printer.

Model Dimensions

The maximum build dimensions of the 3D printer is 8” deep, 10” wide, and 8” tall. You can design in whatever dimensions you want but when you submit the job to be printed it will be scaled down to the dimensions you request proportionally to fit in the build chamber. It is important that the thickness of walls is at least 1.2 mm AFTER it has been scaled otherwise they will not support itself or crack during the cleanup process.

Trapped Powder

If your model has large objects or regions that are hollow inside you need to make sure there is some kind of drain hole to allow powder to be removed. It is important to try and keep the powder consumption low to save money and not weight down parts of the model that need to be supported. A cylinder that is solid, hollow, and with drain holes.