Getting ready

You'll need the toy block that we optimized with Meshmixer.

How to do it...

Open Slic3r and follow the procedure:

How it works...

In the following image, we can see a composite of the first 10 print layers and the resulting pattern:

Each of these patterns is going to produce different results. Some of the differences may be as follows:

In the following image, we can see the differences made in adjusting the infill density:

Most models will be strong enough with an infill of 10 to 25 percent. For gears and pulleys, a higher density of up to 50 percent or more may be best for durability. In principle, try to print with as little as possible. This will speed up the printing process and decrease the amount of filament you expend.

Experimenting with the infill as you progress with your future printing would be a good way to see how the infill patterns and infill solidity affect your model.

Optimizing infill with Skeinforge

Skeinforge has the capability of creating four infill patterns. In this recipe, we'll learn how to select the infill pattern and make the most common adjustments for better optimization.

How it works...

In the following image, we can see that the infill patterns that Skeinforge produces are very similar to Slic3r's infill patterns:

Similar attributes can be made with these patterns as were made with the Slic3r patterns. There are three main considerations to keep in mind with these patterns. They are as follows:

• When selecting the line pattern, it will be quicker to generate, and it doesn't add any extra movements to the print head. This will keep the vibration down.
• When selecting a grid pattern, there will be extra diagonal lines and more filament extrusion. Keeping the infill around 0.2 will give better results.
• The grid patterns are stronger except for the circular pattern. This pattern is weak but is good for minimizing warping of the print.

Printing without fill with Skeinforge

Both Skeinforge and Slic3r have a variety of choices that control infill and thickness. Both slicers have similar controls to make these adjustments, their major difference being nomenclature. Skeinforge will refer to the skin of a model as the shell, and Slic3r will refer to the vertical shells as the perimeter. Both slicers have options for specifying the number of base and top layers to be printed.

In this recipe, we'll see what happens when we print without infill and shells using Skeinforge. The same test could easily be made with Slic3r by reducing the perimeter and base layers to 0. Keep in mind that with both slicers, there is always one shell when printing a model.

How it works...

By changing the values of Extra Shells to 0, we've instructed Skeinforge to create a 1 shell thickness.

Note

The shell width is determined by the Edge Width over Height (ratio) in Skeinforge's Carve plugin. More information about this can be found in Chapter 3, Scanning and Printing with a Higher Resolution.

This is determined by the width size that our hot-end extrudes a line. By changing the Infill Solidity (ratio) to 0, we've instructed the slicer to keep the interior of our model empty. By changing the Solid Surface Thickness (layers) to 0, we've instructed the slicer to remove all solid layers (which is any area that would be printed across the entire model for that layer, such as the first flat layer that makes up the base of the model).

Let's look at the printing results of the three models in the following image:

We can see that distortion occurred in the toy block and statue; there are gaps in the horizontal surfaces. Without activating the solid layers, all of the flat surfaces could not print. The pyramid model printed well because its structure gradually builds on top of each layer in increments. This kept the filament fairly tight without sagging.

Tweaking shells and surface layers with Skeinforge

In this recipe, we'll run a series of tests to see what happens when we make changes in both the number of shells and the surface layers.

How it works...

When we visually compare the results in the following image, we can see that by adding two surface layers with only one extra shell, it made a good print.

For this model, an equal number of shells and solid layers make a good economic model. Remember, we always start with one shell, so by adding one extra shell, we have a total of two.

Let's look deeper into the relationship between shells and layers. In the following image, we can see what happens when we print with extra shells:

When we add shells, we are essentially adding extra thickness to the model's wall. In this model's case, the two additional shells did very little to change the overall appearance of the block.

What happens when we only adjust the surface layers? In the following image, we can see an improvement in the horizontal fill of the model. When more solid layers are added, the overall appearance of the block is better.

There are other factors to be considered as well, such as the width of the extrusion bead. A larger nozzle size would create thicker walls, and this would make a stronger print.

Layer height can also have an impact on the quality of the print. Printing at a lower height would create more layers to print. This will create a more gradual buildup and possibly enclose the gaps better.

Reviewing the print results

Let's take a look at the three different models after printing them with the most efficient settings for the number of shells and surface layers. We'll be able to see what settings work best with each type of model.

We can see the results of printing the statue in the following image. It required three layers and two shells for a successful print. This is the default setting for Skeinforge and proves to be a good starting point for any model.

Next, let's look at the pyramid shape in the following image. It required the least amount of layers and shells for a successful print. It required only one shell.

During the modeling process, any form that can be designed with a gradual build to a point or multiple points will print well. This is a good technique for building paper-thin and hollow models.

There's also another method of printing a hollow form. Slic3r has an option called Spiral vase. By activating it in Layers and perimeters under Vertical shells, this setting will raise the height continuously, thereby avoiding a layer-change point that would cause a visible seam. Just be sure to keep the infill set at 0.

Last, we'll look at the toy block. We can see that the block printed successfully with a reduced amount of both layers and shells; it took only two surface layers and shells to print without infill.

When we print without infill, the most problematic areas will be the horizontal surfaces. Without the support of adequate infill, there will be gaps in the horizontal layers that will have to be bridged. If the gaps are too large, the filament will sag. Bridging is the name of the technique that requires the printer to span a gap from two points. How the printer responds when bridging situations occur is determined by how adjustments are configured with the slicer.