When 3d printing, the filament actually is extruded when laying down a surface (obviously). But when the printer needs to skip across a hole or change layers, it actually retracts the filament into the nozzle for a short period of time. This is a good thing. If these settings are off or if the printer were to stop retracting, you would find a stringy mess of filament across every hole or void in your print.
There are two settings that I want to describe:
- Retraction distance: this is the amount of filament that the printer pulls up into the nozzle. As you can imagine, timing, speed, and retraction distance are all related. If your retraction is set at 6mm, but your acceleration and speed are set so high that the printer only has enough time to extrude 3mm you are going to see some issues on your print, which brings us to the second point.
- Retraction speed: this is the speed at which the printer retracts the filament. Set it too high and your extruder might strip your filament. Set it too low and you will have stringing.
One of the best ways to optimize your retraction is to print a retraction tower. However, printing a retraction tower requires you to update your retraction settings at certain intervals in Z. If you don’t have the ability to do this, trial and error is another alternative that gets you pretty close. Just update your retraction settings by a small interval and see if there is an improvement.