Voron Stringing and Oozing — Complete Retraction Tuning Guide

Troubleshooting Calibration Printing

Stringing and oozing are among the most frustrating artifacts in 3D printing. Those fine, sticky wisps of plastic that connect separate parts of your print — or the blobs that form at the start of a travel move — can ruin an otherwise perfect print. The good news is that on a Voron, you have full control over every parameter that causes these issues. This guide walks you through the complete process of diagnosing and eliminating stringing and oozing on your Voron printer.

Last updated: May 2025. We cover retraction distance and speed, temperature tuning, filament drying, hotend-specific settings, wipe and coast configurations, travel speed optimization, and G-code tweaks. All recommendations are tested on Voron V2.4, Trident, and V0.2 platforms with Stealthburner, Afterburner, and MiniSB toolheads.

What Causes Stringing and Oozing?

Stringing and oozing have four primary causes. Understanding which one is affecting your print is the first step to fixing it:

• Nozzle temperature too high: Molten filament is less viscous at higher temperatures. If the nozzle is hotter than necessary, filament continues to flow out even when the extruder is not actively pushing. The solution is a temperature tower to find the minimum bonding temperature for your filament.
• Retraction distance too low or too slow: When the print head moves from one part of the model to another, the extruder needs to pull filament back into the nozzle to relieve pressure. If this retraction is insufficient, filament oozes out during travel moves, leaving strings. This is the most common cause of stringing after high temperature.
• Moist filament: Wet filament is the great masquerader of 3D printing issues. Moisture absorbed by the filament turns to steam in the hotend, expanding and pushing molten material out of the nozzle unpredictably. Wet filament will string even with perfect retraction settings. Always dry your filament before tuning retraction.
• Travel speed too slow: Slow travel moves give oozing filament more time to form a string between two points. Faster travel moves (200 mm/s or more) reduce this time window dramatically.

Filament Drying — The First Step

Before you change a single retraction setting, dry your filament. Even brand-new filament from the factory can arrive with moisture content of 0.2-0.5%, which is enough to cause visible stringing. This is especially true for filament shipped in humid conditions or stored without desiccant.

Use a dedicated filament dryer (like the Sunlu S2 or Creality Space Pi) or your Voron's heated bed. If using the bed, place the spool on the bed and cover it with a cardboard box for even heat distribution. A Voron's 110°C bed set to 65°C (for ABS) works perfectly for drying.

Temperature Tower — Find Your Sweet Spot

Lower nozzle temperatures produce thicker, less runny molten filament that oozes less. The trade-off is that too-low temperatures cause poor layer adhesion and weak parts. The temperature tower finds the minimum temperature that still produces strong, well-bonded layers.

How to run a temperature tower on your Voron:

• Use Orca Slicer's built-in calibration tools (Calibration → Temperature tower). It generates a G-code file that changes temperature at specific layer heights.
• Print the tower with your target filament. Use a 0.4mm nozzle, standard speed profile (80-150 mm/s), and conservative retraction (1.0mm at 40 mm/s for direct drive).
• Examine each temperature band for stringing, oozing, surface finish, and layer adhesion.

Typical temperature ranges for common filaments on Voron:

• PLA: 190-220°C. Start at 220°C and decrease in 5°C increments. Most PLAs print cleanly at 195-205°C with minimal stringing.
• ABS: 230-260°C. Start at 255°C and decrease. ABS is less prone to stringing than PETG, but lower temperatures reduce the visible effect.
• PETG: 230-260°C. PETG is the most stringing-prone common material. Lower temperatures help enormously. Many PETGs print best at 235-245°C.
• TPU: 210-240°C. Lower temperatures reduce stringing but increase extrusion force, which can cause skipping in low-torque extruders.

"When tuning stringing, always do the temperature tower first. Improving temperature can reduce stringing by 80% or more before you even touch retraction settings. Retraction tuning is for the last 20%."

Retraction Tuning — Distance and Speed

Retraction is the primary tool for preventing oozing during travel moves. When the extruder retracts (pulls filament backward), it creates negative pressure in the melt zone, sucking molten filament back into the nozzle. The key parameters are retraction distance (how far the filament is pulled back) and retraction speed (how fast it's pulled).

Direct Drive Retraction (CW2, Orbiter, Galileo 2, Sherpa Mini)

Direct-drive extruders are mounted close to the hotend — typically within 30-50mm of filament path. Because there's very little distance between the extruder gears and the melt zone, only a small retraction distance is needed:

• Retraction distance: 0.5-1.5mm
• Retraction speed: 30-50 mm/s
• Deretraction speed: 20-40 mm/s (the speed at which filament is pushed back after retraction)

Start at 1.0mm at 40 mm/s. Run a retraction test tower (Orca Slicer → Calibration → Retraction tower). Examine each segment for stringing. Increase distance in 0.1mm increments up to 1.5mm if stringing persists. If you see filament grinding (clicking from the extruder, dust around the drive gears), reduce distance or speed.

Bowden-Extruded Retraction (Remote setups like Orbiter on gantry)

For Bowden or remote-direct setups where there's 200-400mm of PTFE tube between the extruder and hotend, retraction distances are larger because the filament must compress/tension the entire Bowden tube:

• Retraction distance: 2-5mm
• Retraction speed: 40-60 mm/s
• Deretraction speed: 25-45 mm/s (slower to prevent overshooting)

Start at 3.0mm at 50 mm/s. Run the same retraction test tower. Bowden setups are more prone to retraction-related issues like filament grinding and nozzle clogging because the longer filament path creates more friction and hysteresis.

Hotend-Specific Retraction Settings

Different hotends have different internal geometries that significantly affect the optimal retraction distance. Using too much retraction on a hotend with a short melt zone can actually worsen stringing by pulling molten filament into the heat break, where it can cool and clog.

The most common mistake: Using retraction distances from your previous printer or a generic profile. The Revo Voron in particular is sensitive to over-retraction — users coming from a V6 (2-3mm retraction) often set 2mm on their Revo and immediately get heat-break clogs.

Wipe and Coast Settings

In addition to retraction, slicers offer wipe and coast settings that further reduce stringing and oozing by managing the nozzle path at the end of each extrusion segment.

Wipe (Orca Slicer, SuperSlicer, Cura): After completing a perimeter, the nozzle continues moving along the same path for a short distance while retracting. This "wipes" any excess filament off the nozzle tip against the print wall. Recommended: enable wipe with a distance of 2-5mm. In Orca Slicer, this is found under Filament Settings → Retraction → Wipe while retracting.

Coast (SuperSlicer, PrusaSlicer): Before the end of a perimeter, the extruder stops pushing filament while the nozzle continues moving. The residual pressure in the melt zone completes the extrusion. This reduces the blob at the end of a perimeter that causes stringing on the next travel move. Recommended: coast distance of 0.2-0.5mm. Start small — too much coasting causes underextrusion at seam points.

Travel Speed Optimization

The faster the print head moves between two points, the less time molten filament has to ooze and form a string. Travel speed is one of the most underrated stringing-reduction parameters.

Recommended travel speed: 200-350 mm/s. On a Voron V2.4 with a Stealthburner toolhead, 250 mm/s travel speed is a safe starting point. On a lightweight V0.2 with a MiniSB, you can push 300+ mm/s.

Travel acceleration: Set travel acceleration to 5,000-10,000 mm/s² — significantly higher than print acceleration. This ensures the nozzle reaches travel speed quickly, minimizing the time spent at low speeds where oozing is worst.

In Klipper, you can set travel-specific acceleration in your printer.cfg:

printer.cfg:
[toolhead]
max_velocity: 300
max_accel: 10000
max_accel_to_decel: 10000
square_corner_velocity: 5.0

In your slicer, set travel speed separately from print speed. In Orca Slicer: Speed → Travel → 250 mm/s. Enable "Retract on layer change" only if you see stringing specifically at Z-seam points.

Z-Hop vs No Z-Hop

Z-hop (lifting the nozzle slightly during travel moves) is controversial in the Voron community. It helps prevent the nozzle from colliding with already-printed parts, but it introduces two problems:

• Increased print time: Each Z-hop adds the time needed to lift and lower the Z axis. On a V2.4 with a 350mm bed, this adds significant time to prints with many travel moves.
• Z-band artifacts: Frequent Z-axis movement can amplify Z-banding or Z-wobble if your lead screws aren't perfectly aligned.

When to use Z-hop: Only if you see the nozzle dragging through printed parts during travel moves, or if you're printing with materials prone to curling (ABS, Nylon, PC). Keep Z-hop to 0.1-0.5mm maximum — anything higher is wasted time with no benefit.

When to skip Z-hop: For PLA and PETG prints with good bed adhesion, Z-hop is usually unnecessary and adds time and potential artifacts. Disable it entirely and rely on retraction + travel speed.

Retraction Extra Prime Amount

After retraction, the extruder pushes filament back to re-pressurize the melt zone before starting the next extrusion. The "extra prime amount" setting adds a small amount of extra filament to compensate for filament that might have oozed out during the travel move or been lost to retraction-compressed filament.

Recommended: 0.0-0.2mm³ (equivalent to about 0-0.1mm of filament on a 1.75mm filament). Start at 0.0mm³. If you see small gaps or underextrusion at the beginning of perimeters after travel moves, increase by 0.02mm³ increments. If you see blobs or zits at the restart point, decrease or set to 0.

G-Code Tweaks — Firmware Retraction

Klipper supports firmware retraction via the M207 and M208 G-codes. This allows the firmware to handle retraction directly rather than relying on the slicer's retraction G-code. The advantage is consistent retraction behavior across all slicer profiles.

Klipper firmware retraction settings:
[gcode_macro M207]
gcode:
  SET_RETRACTION RETRACT_LENGTH=1.0  ; adjust per hotend
                   RETRACT_SPEED=40
                   UNRETRACT_EXTRA_LENGTH=0
                   UNRETRACT_SPEED=25

[gcode_macro M208]
gcode:
  SET_RETRACTION RETRACT=0

To use firmware retraction, add the following to your slicer's start G-code:

; Orca Slicer / SuperSlicer / PrusaSlicer:
M207 S1.0 F3000 T1  ; retract 1.0mm at 50mm/s (3000mm/min)
M208 S25 F1500 T0    ; deretract at 25mm/s (1500mm/min)

Note: If you use firmware retraction, disable the slicer's retraction settings — otherwise both systems will retract, doubling the retraction distance and potentially causing jams.

Orca Slicer also supports a "Firmware retraction" toggle (Filament Settings → Retraction → Firmware retraction). Enabling this tells the slicer to output M207/M208 codes instead of explicit G1 E-... retractions. This gives you the ability to adjust retraction on the fly via the Klipper console without reslicing.

Complete Tuning Workflow

Here's the recommended sequence for eliminating stringing and oozing on your Voron:

1. Dry your filament — use the temperature/time table above. This alone fixes 50% of stringing issues.
2. Run a temperature tower — find the minimum temperature that produces strong, well-bonded layers.
3. Set correct retraction for your hotend — use the hotend-specific table above. Don't guess based on your previous printer.
4. Run a retraction distance tower — start at the minimum recommended distance for your hotend and increase in 0.1mm increments until stringing disappears or grinding begins.
5. Run a retraction speed tower — start at 30 mm/s and increase in 5 mm/s increments up to 60 mm/s. Watch for grinding at high speeds.
6. Enable wipe — set wipe while retracting to ON with 2-5mm distance.
7. Set travel speed to 250 mm/s+ — reduce the time window for string formation.
8. Test with a real print — use a stringing test model (like the "retraction test" in Orca Slicer's calibration menu).

If stringing persists after all these steps, the issue is almost certainly wet filament. Dry it again — longer, at a slightly higher temperature (within safe limits), and consider using a dry box for printing.