Blobs and stringing
A screw extruder cannot pull material back the way a filament printer retracts. What comes out at corners, at the start of a line, and across a travel move is pressure that has nowhere else to go — so the fixes are about pressure, not about retraction distance.
Blobs at corners and direction changes
Section titled “Blobs at corners and direction changes”Two causes, told apart by whether the walls are otherwise right.
- Over-extrusion everywhere, blobs just being where it shows most: check Rotation Volume first — it is the flow calibration on this machine. Only after that, a flow-ratio change
- Printing above the material’s MVS: pressure builds in the barrel and releases at every slowdown. See Max Volumetric Speed
- Pressure Advance is the setting made for this — it compensates the lag between the screw and the nozzle. Tuning it is its own page: Pressure Advance tuning
Extra walls, doubled walls, odd Z moves
Section titled “Extra walls, doubled walls, odd Z moves”The Classic wall generator divides a wall into a fixed number of lines and gets it wrong whenever the wall is close to the line width — a 7 mm wall with a 5 mm nozzle, say. Use Arachne, on every nozzle: Process → Quality → Wall generator. See FGF-specific settings.
Stringing across travel moves
Section titled “Stringing across travel moves”Ooze during travel, since the nozzle cannot suck back:
- Z-hop lifts the nozzle clear of the print on the way. Shipped values are per nozzle — see FGF-specific settings
- Drop the nozzle zone 5–10 °C. Stiffer melt, less drip. Too far and it stops flowing evenly
- Arachne again — it plans fewer travel moves
A blob at the start of every line
Section titled “A blob at the start of every line”The “un-retraction blob”: material that pushes out at each restart and builds until the nozzle catches on it. That is the retraction settings, and on this machine they are volumes, not distances. The units, the shipped values and how to tune them live are on FGF-specific settings.
A thin or ragged first purge line
Section titled “A thin or ragged first purge line”Normal. The barrel is still settling to temperature when the skirt starts, and the first one to three lines show it. If it does not clear after that, it is not this page: see Nozzle and barrel clog.