My background has always been in software. While I have tinkered with engineering (the physical kind), it has never been extensive. So, when I started to get into 3D Printing, it was with a keen eye to how software helps this process. The slicer is what has impressed me the most so far in this space.
As we look at the process of 3D printing, it necessarily starts with a design. There is a plethora of tools available today to create these designs, each with its own strengths and abilities. These tools are a far cry from my youth, but that is a discussion for another time. The process ends with the printer printing thin layers of material in order to make the design real.
But, how does one get from a design to those layers being printed. The printer is simply obeying orders given to it in a “gcode” file. The software which creates these instructions from the design is called a Slicer.
The slicer takes in multiple inputs – the design, the printer and its capabilities, the raw material and its properties. Then it does the heavy lifting to determine the best way to print the product.
3D Printed parts are typically hollow. But what does hollow mean? All external surfaces on a design are considered “walls”. It is the area inside these walls that are called infill. An infill of zero would mean completely hollow but would make the print extremely weak. An infill of 100% percent would make a solid print, but would negate multiple advantages of 3D printing. Generally, 3D prints are printed with an infill of about 20%, but this could vary greatly depending on the application of the print. So, when slicing, you specify the thickness of the wall, the infill percentages you want and, maybe, the pattern you want the infill in (the pattern also contributes to the strength of the print along different axes). The slicer automatically determines the boundaries of the design, creates the walls and the infill patterns and specifies it in the gcode file. The below are some examples of different fill patterns at different densities.
While 3D Printers can do a lot, they certainly cannot print in thin air. They need a base to print on. So, how do you print a horizontal part coming out of a vertical one, such as the arm on the figure below? The answer is supports. Supports are printed along with the design in a way that they provide a base to such surfaces and can be removed once the print is done. While supports can be incorporated into the design, it is a tedious job to identify every surface that needs support and create one for it. In comes the slicer. You can tell the slicer that you would like supports and the angle at which your printer would not be able to print the overhang (typically 45 degrees). The slicer then identifies the surfaces and automatically creates the supports for them.
In the end, the slicer does an impressive job of analysing the design and performing multiple functions that end up making the job of 3D printing much easier. Most industrial machines come with their own slicer that can do the job. However, there are multiple slicers that can be used for hobbyist machines, some of them open source. I will surely keep a close eye on what else will be handled automatically by these products. Any ideas?