When the nozzle of a 3D printer has to move across a gap without printing anything, you can often face an issue called oozing. Oozing is the result of the filament being left in the hot nozzle. When being consistently extruded, the filament melts enough to be printed. If there’s a pause when it’s in the melt zone, that part of the filament will keep getting hotter and runnier until it oozes out of the nozzle without any assistance.
Still, it cannot be easy to get the settings perfect in practice. The solution to oozing is pretty simple in concept. Retraction allows you to turn the extruder in reverse gear, which pulls the filament back away from the tip of the nozzle.
The intention of retraction isn’t to pull the filament all the way out of the melt zone – doing so would cause other problems – but to pull it back enough that it won’t ooze out of the nozzle so easily.
Retraction can be an incredibly effective feature at preventing oozing. To get the most out of it, however, you may need to tune the settings. The most important setting is obviously enabling retraction; after that, you should configure the retraction distance.
You generally will want this to be in the order of a few millimeters. Most slicing software suites default to between two and seven millimeters. You should avoid setting the retraction distance too high, as doing so can cause clogs. A general guide to follow is to keep the retraction distance lower than the length of the nozzle.
Retraction speed controls how fast the filament is retracted. If this setting is too low, it can result in oozing before the filament retracts far enough. Generally, the default speed setting in slicer software suites is adequate.
Minimum travel distance allows you to configure your printer to avoid retractions for small gaps. Small gaps don’t suffer from as much oozing as big gaps as the filament doesn’t have the time to ooze. Configuring this setting too low can result in the extruder grinding the filament. A low minimum travel distance can also slow down your print as the retraction must be completed before printing can resume.
Retraction is a beneficial tool for countering oozing, although it’s never perfect. Have you got any other tips to share for configuring retraction? Feel free to share them down below.