Designing around the manufacturing processes available is a challenge that all engineers face. A design is only as good as it can be manufactured, and all processes have their limitations. 3D printing is no limitation. This section will briefly explain how to design around these limitations to decrease print time as well as increase the likelihood of a successful print.

Minimizing Support Material:

3D printers cannot print over open air and as a result must build a support structure whenever there is a large overhang. This material is then broken off of the 3d print and thrown away. Support structures can occasionally break free from the bed, resulting in a failed print, this can also reduce the surface finish quality. To increase the likelihood of a successful print, the amount and height of support structure should be minimized.  

Planning for a Large Adhesion Layer:

In order for a print to be successful, it must remain in the same place on the print bed during the duration of the print. The melted plastic often forms a bond with the bed as the first layer is being printed. This adhesion is dependent on the surface area of the face on the bed. Often times, tall prints with a small first layer surface area will fail, as the part breaks free and falls over when printing. To prevent this, try to design around a single, somewhat large face which can be printed face down on the bed. Another option is to cut a complex part in half and print the sides separately before then gluing the two halves together.

Avoid Printing Large Detailed Parts:

3D printers work by laying down 2D layers of filament on top of each other. The easiest way to increase the quality of a 3D print it to minimize the height of each layer. This means that the 3D printer must make more passes, resulting in a significantly longer print time. For most prints, a standard (.2 mm) or fast (.3 mm) print speed is a more than sufficient to achieve a good surface quality while maintaining a small print time. Large parts with small layer heights can take as long as 48 hrs to print. Sometimes it may be necessary to print a large part with the need for high detail in only a few isolated areas. To do this, it is recommended that the part is split into multiple components, so that the smaller, detail-oriented piece can be printed separately at a finer layer height, while the larger piece can be printed at a larger, faster layer height.

These suggestions are not required, but serve as guidelines that will increase the likelihood of a successful print, effectively decreasing the wait time between submitting your request and picking it up.

Regardless of which software is used to design and model your part, all parts must all be saved as a .stl file before being printed. A STL file is a 3D modeling file with the bare minimum amount of information needed to allow the printer to determine the geometry. These files are then fed into a slicer software which instructs the printer how to build the piece. At the Engineering Lab, we require students to submit .stl files. To create a STL file, select save as and click the drop down box next to file type, which should reveal an option for .stl.