Enable cooling fans
With this setting you can enable or disable the print head fans during printing. The print head fans will make sure that the material is properly cooled before the next layer is placed on top of it. Especially on layers with a short layer time and layers with bridges/overhangs, cooling will increase the print quality.
When the print head fans are enabled you can set a few more fan parameters. One of them is the fan speed, which defines the speed at which the fans spin. A higher fan speed allows for better cooling and reduces oozing, but can also increases the shrinkage of the material. This means that the fan speed may be different per material. The preset material profiles on the Ultimaker already contain the default values for Ultimaker materials.
This setting is divided in the following parameters:
- Regular fan speed: The speed at which the fan spins before hitting the threshold. When a layer prints faster than the threshold, the fan speed gradually inclines towards the maximum fan speed.
- Maximum fan speed: The speed at which the fan spins on the minimum layer time. The fan speed gradually increases between the regular fan speed and maximum fan speed when the threshold is hit.
Regular/maximum fan speed threshold
This setting defines the layer time at which the fan will switch between regular fan speed and maximum fan speed. Layers that print slower than this time use the regular fan speed. For faster layers the fan speed gradually increases towards the maximum fan speed.
Regular fan speed at height
The height at which the fans will spin on full speed, based on the regular fan speed. At the layers below, the fan speed gradually increases from zero to regular fan speed. It’s also possible to specify this parameter by adjusting the layer number at which the fans should be on full speed.
Using a higher value increases the adhesion to the bed, but can also lead to oozing and thus reduced print quality. Printing with the fans full on from a height of 0.5 mm is usually sufficient.
Initial fan speed
This setting controls the fan speed on the intial layer only, which sticks to the build plate. The speed then increases to the regular fan speed, which is hit at the regular fan speed height setting.
Minimum layer time
The minimum layer time determines the time it at least should take to print one layer. If a layer would take less than the set value, the printer will slow down, so that the minimum layer time is reached. This allows the printed material to cool down properly before printing the next layer.
This is the minimum speed at which the printer is forced to print at, despite slowing down due to the minimum layer time. When the printer would slow down too much, the pressure in the nozzle would be too low and result in bad print quality.
If a minimum layer time of for example 5 seconds would require the printer to print at a print speed of 8 mm/s it will only do that if at least 8 mm/s is set as minimum speed. If the minimum speed would be 10 mm/s, it means that it won’t print slower than 10 mm/s and that the layer time will change accordingly (and thus can be shorter than 5 seconds).
By enabling this setting you allow the print head to move away from print when it’s printing at the minimum speed but has not yet reached the minimum layer time. The print head will wait until the minimum layer time has passed and will then move back to the print to continue. This gives the printed material enough time to cool down while the minimum speed is used.