Orca Slicer retraction calibration
Retraction calibration finds the smallest amount of filament pull-back that stops stringing between parts of a print. When the nozzle travels across open space, pressure left in the melt keeps oozing plastic and leaves fine strings behind. Retraction pulls the filament back a little before the travel move to relieve that pressure. Orca Slicer prints a pair of towers with the retraction distance rising as they get taller, and you pick the shortest distance that leaves no strings. It is the last calibration to run, once temperature and flow are already correct.
What retraction does
Retraction briefly reverses the extruder before a travel move, which drops the pressure at the nozzle so it stops oozing while it moves. Too little, and you get strings and blobs between parts. Too much, and the filament pulls back so far that the next line starts with a gap or a skip, and the extra grinding can wear the filament. The goal is the shortest retraction that removes the strings without starving the start of the next move, because a shorter retraction is faster and gentler on the filament.
Before you start
Get temperature and flow right first. If strings appear at every retraction distance in the test, the real problem is usually a nozzle that is too hot or filament that is damp, and no amount of retraction will fix that. So run the temperature tower and flow rate tests before this one, and dry the filament if it has been open a while. Retraction behaviour also depends heavily on your extruder type: a direct drive extruder needs only a small pull-back, while a Bowden setup needs a much larger one because of the long tube between motor and nozzle.
How to run it
- Start a new project, then open the Calibration menu and choose Retraction Test.
- Set the start length, end length and step. The defaults suit a direct drive extruder, roughly 0 to 2 mm in small steps; a Bowden setup needs a higher range, often around 1 to 6 mm.
- Keep Z-hop on its Normal setting for the test.
- Slice and print the two towers. In the preview you can move the seam to an inner face so the strings are easier to see.
Reading the result
Look in the gap between the two towers, where the travel moves happen. Find the height where the strings disappear. Each height corresponds to a retraction distance, rising from the bottom up, so the lowest clean height gives you the shortest retraction that works. Prefer the shortest distance that removes the strings, rather than the largest, and check that the tower surface at that height has no gaps or blobs from pulling back too far.
Saving your retraction
Enter the retraction distance you found, which is set in the printer’s extruder settings, and save it. It also helps to set a sensible retraction speed: around 30 to 40 mm per second for a direct drive on PLA or PETG, and slower for flexible filament like TPU. After saving, start a new project to leave calibration mode, then print a quick two-pillar stringing test to confirm the strings are gone. If any remain, the troubleshooting guide walks through the wider causes of stringing, and it is worth rechecking temperature before pushing retraction any higher.
Frequently asked questions
What is retraction calibration in Orca Slicer?
It is a test that finds the smallest filament pull-back that stops stringing. Orca Slicer prints two towers with the retraction distance rising as they get taller, and you pick the shortest height with no strings between them. That distance goes into the printer’s extruder settings.
What retraction distance should I use?
It depends on your extruder. A direct drive extruder usually needs only a small amount, often under 1 mm, while a Bowden setup needs much more, commonly several millimetres, because of the tube between the motor and the nozzle. The test finds the right value for your exact machine, so use what it gives rather than a fixed number.
Why do I still get stringing after calibrating retraction?
Because stringing is often not a retraction problem. If strings appear at every distance in the test, the nozzle is usually too hot or the filament is damp. Run the temperature tower again and dry the filament, since retraction cannot fix heat or moisture. Only then push retraction higher.
Should I run retraction before or after temperature?
After. Retraction is the last calibration to run, once temperature and flow rate are already correct. If you tune retraction first and then change the temperature, the retraction value is no longer right and you have to redo it, so the order saves work.
Does retraction fix stringing on its own?
Not always. Retraction is the main tool for stringing, but it only works when temperature and flow are already in the right place. A too-hot nozzle, wet filament, or fast travel moves all cause strings that retraction cannot fully remove, which is why the calibration order matters.