Now it's time to convert your STL model into something a 3D printer can interpret. Slicing software will accomplish this by "slicing" your STL file into layers. Each layer will be filled with paths for your printer to follow. These paths will be saved as gcode, which is a text language that your printer can read.

Open your slicing software. I am using Slic3r simply because I spent the most time tweaking my print settings in it.

Load your model by clicking the "Add" button (Figure 11.1). Navigate to your STL file location and click "Open" (Figure 11.2).

Position the model on the plater (build surface) to your liking by clicking the model and dragging it (Figure 11.3). I like to print on the back surface of the text so that the perimeters of the letters are drawn smoothly by the printer (Figure 11.3). To rotate your part, right click on the part, select rotate, and type the desired angle of rotation for the corresponding axis of rotation (X is red, Y is green, Z is blue). If you modeled the base text on the XY plane, as done in this example with Fusion 360, your part will already be facing the correct direction.TIP: If you print with the letters standing how they are intended to sit on your desk the perimeters of the letters will be layered and not look as crisp. Printing on the back also helps avoid the need for extra support material. Since our cut was made at 45° each new layer of the cut has enough material below it to stick and is typically printable. If we were to print the letters standing up, characters like "T" would need support in order to print the overhangs accurately. TIP 2: To avoid having to guess the angle of rotation for your model in a slicer, model it in Fusion 360 in the orientation you want it to print. Most printers build platforms correspond to the XY plane.

Adjust your print settings. In this example PLA filament settings are shown in Figures 11.4 through 11.9. Since this print is ornamental, I used a 40% infill to save plastic and time (Figure 11.5). As seen in the Figure 11.6, I chose to print a 5mm brim to increase the surface area of the print on the heated bed. A wide print like this tends to warp and detach from the print surface so a brim is cheap insurance against a failed print. This print ended up sticking very well and I wished I didn't used a brim because it was frustrating to remove it from between letters.

You must choose whether you want to print support material at this point (Figure 11.7). There will likely be overhangs which have no underlying surface on which to print (detailed later in Figures 11.13 through 11.17). If you have this condition and don't print support there will nothing for the plastic to stick to on these layers. This will ruin your print or, at best, create flying-spaghetti-monster-like strands you will need to grind off. However, unless you have soluble support or really good model material support settings, there will probably be some picking and grinding to remove the supports anyway. As seen in my settings (Figure 11.7), I chose to print support with a threshold of 0° which allows Slic3r to decide when and where supports are needed. Slic3r did a good job with the support (this time anyway) as you will see later. I have printed the illusion acceptably without support (the example of my name had no support), but I did have to grind some "spaghetti" from the bottom of overhangs.

Wait for Slic3r to finish computing (if auto-compute turned off, click "Export to G-code and save in order to compute) and click on the "Preview" tab at the bottom of the window (Figure 11.10). You will now see your print paths modeled in 3D. Figure 11.11 shows what a pillar of support looks like. The skirt and brim are detailed in Figure 11.12. You can use the slider on the right side of the graphics area to move through the layers of print paths (Figure 11.13). Figures 11.13 through 11.17 highlight where and why support material was needed. For this print the case shown in Figure 11.7 would not have printed without support because it is so close to the last layer. Since the small bit of model shown there is detached from the rest of the body, the remaining few layers will have nothing to bridge to.

If you don't like what you see after investigating your paths, go back and change your print settings, or load your CAD model in Fusion 360 and adjust your model.