Underextrusion, when the printer does not extrude enough filament. Space (gaps) between the perimeter and the infill.
The profiles of Simplify3D contain settings that determine how much filament the 3D printer should extrude. However, sometimes less filament is extruded than the software calculated. This is called underextrusion. You may notice underextrusion when holes appear between the layers.
To test if the 3D printer is extruding the right amount of filament, it is recommended to print a test cube with 2 perimeters, and no top or bottom layers. The thickness of the wall should now be twice as thick as the set extrusion width (default 2×0,48=0,96mm for a 0.4mm nozzle) You can now set your new extrusion multiplier using this formula:
(Extrusion width / Measured wall thickness) x Extrusion Multiplier
Check the hot end for debris
Make sure that the nozzle is clear from a build-up of filament and dirt.
Check the filament diameter
The first thing to check is if the correct diameter of the used filament is set in the Simplify3D software. Click on “Edit Process Settings” and go to the Other tab. Make sure that the set value matches the filament you are using. If necessary, you can measure the filament using a pair of calipers.
The most common diameters for filament are 1.75mm and 2.85mm and the diameter can often be found on the plastic spool.
Set the extrusion multiplier
If your diameter is set correctly but there is still underextrusion, then you need to adjust the extrusion multiplier. This is a setting in Simplify3D that allows you to easily adjust the amount of extruding filament (otherwise known as the flow rate). You can find this setting by clicking on “Edit Process Settings” and going to the Extruder tab. Each extruder on the 3D printer can have a separate extrusion multiplier, so if you want to change the flow rate for a specific extruder, select the extruder you want from the list on the left. Then load the settings of the chosen extruder.
For example, if you increase the extrusion multiplier from 1.0 to 1.05, the extruder will inject 5% more filament.
Note: For PLA an extrusion multiplier of 0.95 is common. For ABS this is often more towards the 1.0.