The print speed defines the speed (in mm/s) at which the print head moves while printing. Based on this setting, Ultimaker Cura calculates the extrusion flow. The print speed can be visualized per feature in the Layer view > Feedrate.
A higher print speed will lead to a shorter print time. Keep in mind that increasing the print speed means that you may have to increase the temperature as well to ensure the filament is properly melted.
Although you can choose one overall print speed for the complete print, it is also possible to use different print speeds for specific parts of the print:
Infill speed: The speed at which the infill material is printed. If the visual quality of the infill is not important, you could use a higher speed for the infill. However, keep in mind that this may affect the strength of your print.
- Outer wall speed: The speed at which the outer walls are printed. Printing the outer wall slower usually results in a better surface finish.
- Inner wall speed: The speed at which the inner walls are printed.
- Top/bottom speed: The speed at which the top and bottom layers are printed. A lower speed increases the reliability of closure on the top layers, especially for large-area prints.
- Top surface skin speed: The speed of the top surface skin layers. These have to be enabled in the shell category.
- Support infill speed: The speed at which support structures are printed. The quality of the support is not usually important, so a higher value can often be used here.
- Support interface speed: The speed at which support roofs and bottoms are printed. Since these need to adhere to the model properly, they should be printed at a slower speed.
This image shows the visualization of the different print speeds per model feature
This is the speed at which the print head moves when it’s not extruding. A higher travel speed decreases the chance of filament oozing from the nozzle, resulting in a cleaner object. However, higher speed could also cause the nozzle to hit a previously printed part, which may damage the print due to the heated nozzle. This can be prevented by using Z-hop when retracting.
The travel speed for the initial layer differs from the rest of the print to ensure proper adhesion with the build plate.
Initial layer print speed
With this setting, you can specify the speed for the first layer of the print. By default a low speed is used for the bottom layer, so that the material adheres well to the build plate on the first layer.
Initial layer travel speed
With this setting, you can specify the travel speed for the first layer over the print. Keep this setting low to keep the nozzle from pulling the print of the build plate, especially when working with detailed bottom surfaces.
It is possible to adjust the speed at which the skirt or brim is printed. Usually, this is similar to the initial layer speed.
Z Hop speed
This setting changes the speed for all build plate moves during the print. This includes all layer changes and Z-hops. Normally the Z-speed is set at its maximum and capped by the firmware of the machine.
Number of slower layers
This setting defines the number of layers it takes to reach the print speed from the bottom layer of the print. The speed will incline linearly over the number of layers specified, based on the initial layer speed and print speed. A higher value decreases the chance of warping, but can also increase the print time significantly.
In the example above the number of slower layers is set to four, which means that after the fourth layer the set print speed settings will be used
Flow equalization ratio
Printed lines with variable line widths are printed in different speeds to ensure the flow within the nozzle changes as little as possible. The flow equalization ratio determines the correction to this flow and can be adjusted to compensate the flow further when needed.
Example: This 3D model has been sliced with the default value of 110% 'flow equalization ratio'. As seen here, the line widths vary while the flow remains the same throughout the printed part.
Enable acceleration control
Acceleration is a very important part in printing. Just like a car, the print head needs to accelerate to get to the speeds as explained above. The acceleration reduces the speeds set in the firmware, making the print a little slower, but more accurate. Disable the setting to get the maximum acceleration.
This is a theoretical image that shows the difference between speed, acceleration and jerk
Enable jerk control
Jerk defines the speed of the print head before performing a hard stop. Just like a car, the print head needs to come to a complete stop at some points. It's comparable to hitting the brakes in a car. When you do this at high speeds it feels uncomfortable. The jerk settings reduce the speeds set in the firmware, making the print a little slower, but more accurate. Disable the setting to get the maximum jerk.
Continue reading about Travel settings.