1. Locate 3D models online

There are many websites providing a variety of 3D files you can download for free. If the file extension is not ‘stl’, you would need a 3D software to convert the model to stl format. “Thingiverse” is our most favorite site, because most of the files contributed are in stl format for free. We look for 3D models with higher resolutions to avoid limitations posed by the image itself. We use 3D Eiffel Tower as our main testing model for tuning printing parameters of our machine and our PSP (Passive Self-Peeling) mechanism. We have printed more than 80 of them with different sizes. The tallest one is about 9.4 inches, whereas the smallest one is 3.5 inches tall with pillars as tiny as a strand of hair.

2. Check and fix files

All downloaded 3D files need to be checked before slicing and printing. A lot of them may even require repairs. Check your STL files to ensure:

• all objects maintain “outside” orientation.
• the surface of all objects is closed and there are no overlapped faces.

We use “Netfabb basic” to repair models. If the number of shells is too high or “Netfabb basic” fails to fix the model, you would need to upload the stl file to “Netfabb cloud” for further repair.
Sometimes, multiple shells could get you a problematic hollowed model in the following step.

3. Hollow 3D models if necessary
Most of the models require hollowing to save printing materials. In addition, hollowing minimizes light exposure area and greatly reduces layer separation force. The printing time is thus shortened and the printing quality is enhanced.

We use “Meshlab” to hollow our 3D models by building a smaller offset model with inverted surface.
(To Be Continued….)