Shell

Wall thickness

This setting adjusts the thickness of walls of the model. Cura will approach the value set here as much as possible by calculating how many walls should be printer with the given nozzle. A value of 1mm, results in 3 walls of 0,35mm = 1,05mm wall.

wall-thickness
The model on the left has 3 walls, the model on the right has a single wall.

In general a wall thickness of 2 or 3 times the line width is sufficient. A higher value will create a sturdier model and decreases the chance of leaks, while a lower value can significantly decrease the print time and filament costs.

Wall Line Count
Instead of setting a thickness in millimeter of the walls, you can also set a number of walls. When you set the wall line count, the wall thickness is calculated and will grey out.

Top/bottom thickness

With the top/bottom thickness you can set the thickness of the solid printed top and bottom layers of the print. A higher value ensures all gaps on the top and bottom layers get closed completely. On the other hand, this can also increase the print time and amount of filament being used.

We advise to always use a multiple of the layer height for the thickness of the top and bottom. This means for example that with a layer height of 0.15 mm, it’s better to set the top/bottom thickness to 0.6 mm than 0.7 mm.

Seperate top or bottom thickness
You can also set the thickness of the top and bottom layers separately. Especially for the top you may sometimes need quite some layers to close it properly and to prevent “pillowing”. By being able to use fewer layers for the bottom you can easily save some material and print time.

Number of Top/Bottom layers
Instead of setting a height in millimeter for the top or bottom layers, you can set a specific number of layers. The resulting height in millimeter will be calculated automatically depending on the layer height set. Example: Number of top layers 12 * 0.1mm layer height = 1.2mm top layer thickness.

Top/bottom pattern

Cura allows you to choose from different printing patterns for the top and bottom layers. These are the available patterns:

  • Concentric: The pattern is printed from the outside to the center of the print.
  • Lines: A diagonally printed pattern, with travel moves on the shell of the model.
  • Zig Zag: A diagonally printed pattern, with connections on the shell of the model.

bottom-top-patterns-complete
The model on the left has lines pattern, the model on the right uses the new concentric pattern.

Bottom pattern initial layer

The pattern of the first layer printed can be altered here. Top and bottom layers are typically best to be printed with a line or zig zag pattern. Changing only this layer to concentric could improve your model finsih for the bottom layer.

Top/Bottom line direction

The top and bottom layers usually print in a 45° angle. At this angle, both the X- and Y-motor work together, to obtain maximum acceleration and jerk on the layer without losing quality. If for some reason the lines have to be printed in a different direction, you can set it here. 0° is vertical and 90° is horizontal. For example: [0,90] results in a horizontal - vertical top/bottom pattern.

Outer wall inset

This setting compensates the position for the outer wall, if the line width chosen is smaller than the nozzle. Example: Line width 0.35 with a 0.40mm nozzle, leaves a gap of 0.05mm on both sides of the actual printed line. A compensation of 0.025 is set to compensate for the outermost part.

Outer before inner walls

This setting determines which walls are printed first, the outer or the inner walls? When enabled, the outer walls are printed first and X-Y dimensions are more exact. The downside is that overhang quality is decreased.

Alternate extra wall

This setting adds an extra wall every other layer. This way the infill gets caught between the walls, resulting in stronger prints. When you for example set the wall line count to 2 walls and enable alternate extra wall, it will print 2 walls on even numbered layers and 3 walls on odd numbered layers.

alternate-extra-wall

Compensate wall overlaps

With this setting the extrusion on printed parts is reduced, where the print head has to go over a thin area twice. This way all walls are printed without the part being over extruded. The setting can be enabled for the outer or the inner walls seperately.

Compensate-wall-overlap

Fill gaps between walls

For fine detail, the printer might need to print areas that are thinner than the nozzle size. This happens especially, between the outer and inner walls where the model ends in sharp corners. This option allows these gaps to be filled after printing both walls. The illustration shows a droplet which has to be printed.

Note: See how the fill gaps option influences the travel moves. The printer has to come back to the gap at later times to fill it.

Fill-gaps-between-walls

Horizontal expansion

Horizontal expansion can greatly help you if the tolerance of the print is important. Due to the slight deformation of plastics the actual dimensions of the print may not completely correspond with the dimensions of the digital model. By adjusting the horizontal expansion value you can compensate for this slight deviation. A higher value will increase the X/Y size of the model, while a negative value decreases the X/Y size.

Horizontal-expansion
Horizontal expansion -1 mm, no horizontal expansion, horizontal expansion +1 mm

Z seam alignment

This setting allows you to choose where each new layer in the Z direction starts, and thus where the seam of the model will be. Especially on models with consecutive equal layers the seam is usually visible. By changing the Z seam alignment you can decrease the visibility of the seam. These are the options:

  • Shortest: The next layer starts at the endpoint of the previous layer. This is the fastest way of printing, but also creates the most visible seam.
  • Back: The next layer starts at the back of model (as positioned on the build plate). This allows you to choose the position of the seam by rotating the model in Cura.
  • Random: The next layer starts at a random point on previous layer, which eliminates the chance of a seam. Print time will increase due to the necessary travel moves though.

Ignore small Z gaps

Small gaps between the layers in the Z-direction of a model can be “fixed” by using the ignore small Z gaps setting. This setting - enabled by default - will make sure the layers will fuse by printing infill in between the bottom and top of the gap. If you would disable this setting, it won’t fill the gap and will simply print the bottom and top as they are in the model.

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