How to Fix Blobs and Zits in 3D Printing: Simple Solutions

Blobs and zits in 3D printing happen when excess filament oozes out during travel moves or when the nozzle stops extruding. To fix this, adjust retraction settings to pull filament back before moving and fine-tune print temperature to reduce oozing.

Why This Happens

Blobs and zits occur because the printer nozzle leaks extra filament when it stops or moves between print areas. This happens if the filament keeps flowing slightly due to insufficient retraction or too high temperature. The nozzle deposits small unwanted lumps on the print surface.

ini

; Example of slicer retraction settings causing blobs
retraction_enabled = false
nozzle_temperature = 230  ; too hot for PLA
travel_speed = 150

Output

Print shows small blobs and zits at layer starts and travel points.

The Fix

Enable and increase retraction to pull filament back before travel moves, stopping oozing. Lower the nozzle temperature to the recommended range for your filament to reduce melting excess. Also, increase travel speed to minimize time nozzle spends over open areas.

ini

; Fixed slicer settings to reduce blobs and zits
retraction_enabled = true
retraction_distance = 6.5  ; pulls filament back 6.5 mm
retraction_speed = 40      ; retracts filament quickly
nozzle_temperature = 205  ; optimal for PLA
travel_speed = 200         ; faster moves

Output

Print surface is smooth with no blobs or zits visible.

Prevention

To avoid blobs and zits in future prints, always calibrate your retraction settings when changing filament types or brands. Keep your nozzle clean to prevent buildup that causes irregular extrusion. Use slicer preview tools to check travel moves and enable "Combing" or "Avoid crossing perimeters" to reduce travel over open areas.

• Regularly clean nozzle and extruder gear
• Use recommended temperature ranges for each filament
• Test and fine-tune retraction distance and speed
• Enable travel optimization features in slicer

Related Errors

Similar printing issues include stringing, where thin threads of filament appear between parts, and under-extrusion, where filament flow is inconsistent causing gaps. Stringing can be fixed by increasing retraction and lowering temperature, while under-extrusion requires checking filament feed and nozzle clog.

Key Takeaways

Enable and adjust retraction settings to prevent filament oozing during travel.

Lower nozzle temperature within filament guidelines to reduce excess melting.

Increase travel speed to minimize nozzle time over open areas.

Keep nozzle clean and regularly maintain your printer.

Use slicer travel optimization features to avoid unnecessary nozzle moves.